R-03-02-13-13B1 - 2/13/2003J
CAPITAL AREA PLANNING COUNCIL
INTERLOCAL CONTRACT FOR ORTHOPHOTOGRAPHY
Art. 1. Parties and Purpose
1.2. The City of Round Rock (the "City") is a Texas home -rule municipality that is
seeking to obtain orthophotography mapping services.
RECEIVED MAR 0 3 2003
1.1. The Capital Area Planning Council ( "CAPCO ") is a regional planning commission
and political subdivision of the State of Texas organized and operating under the Texas Regional
Planning Act of 1965, as amended, chapter 391 of the Local Government Code.
1.3. CAPCO has contracted with Sanborn Colorado L.C.C. ( "Sanborn ") to provide
orthophotography services. This contract is entered into between CAPCO and the City under
chapter 791 of the Government Code so that the City can contribute to the cost of CAPCO's
contract with Sanborn and Sanborn can provide the City with additional orthophotography
mapping.
Art. 2. Goods and Services
2.1. CAPCO agrees to furnish the City the orthophotography mapping prepared by
Sanborn for the City under its contract with CAPCO. The orthophotography mapping
specifications and timetable for delivery are described in the Attachment to this contract.
Art. 3. Contract Price and Payment Terms
3.1. The City agrees to compensate CAPCO in the total amount of not to exceed $69,992
for goods and services furnished the City under this contract. The City represents that it has
current revenues available on the effective date of this contract to make all payments required by
this contract.
3.2. The City agrees to pay CAPCO the total contract price in installments as work is
completed and invoiced.
3.3. CAPCO agrees to invoice the City for the payments when due under paragraph 3.2,
and the City agrees to pay CAPCO the invoiced amount within 30 calendar days from the date of
the invoice.
Art. 4. Effective Date and Term of Contract
4.1. This contract takes effect on the date it is signed on behalf of CAPCO and it ends,
unless sooner terminated under Art. 6, on September 30, 2003.
f2 -o3 -o - / 3 -/3 L3)
Art. 5. Nondiscrimination and Equal Opportunity
5.1. CAPCO and the City shall not exclude anyone from participating under this
contract, deny anyone benefits under this contract, or otherwise unlawfully discriminate against
anyone in carrying out this contract because of race, color, religion, sex, age, disability,
handicap, or national origin.
Art. 6. Early Termination of Contract
6.1. If CAPCO or the City breaches a material provision of this contract, the other may
notify the breaching party describing the breach and demanding corrective action. The breaching
party has five business days from its receipt of the notice to correct the breach, or to begin and
continue with reasonable diligence and in good faith to correct the breach. If the breach cannot
be corrected within a reasonable time, despite the breaching party's reasonable diligence and
good faith effort to do so, the parties may agree to terminate the contract or either party may
invoke the dispute resolution process of Art. 7.
6.2. If the City fails to pay CAPCO the full contract price set out in paragraph 3.1,
CAPCO and Sanborn jointly own with the City any goods and services provided the City but not
paid for. Joint ownership of these goods and services is automatically established among
CAPCO, Sanborn, and the City at the time of termination for nonpayment under paragraph 6.1
and continues until Sanborn is paid in full for the goods and services provided, at which time the
City becomes the sole owner of the goods and services.
6.3. Termination for breach under paragraph 6.1 does not waive either party's claim for
damages resulting from the breach,
Art. 7. Dispute Resolution
7.1. The parties desire to resolve disputes arising under this contract without litigation.
Accordingly, if a dispute arises, the parties agree to attempt in good faith to resolve the dispute
between themselves. To this end, the parties agree not to sue one another, except to enforce
compliance with this Art. 7, until they have exhausted the procedures set out in this Article.
7.2. At the written request of either party, each party shall appoint one nonlawyer
representative to negotiate informally and in good faith to resolve any dispute arising under this
contract. The representatives appointed shall determine the location, format, frequency, and
duration of the negotiations.
7.3. If the representatives cannot resolve the dispute within 30 calendar days after the
first negotiation meeting, the parties agree to refer the dispute to the Dispute Resolution Center
of Austin for mediation in accordance with the Center's mediation procedures by a single
mediator assigned by the Center. Each party shall pay half the cost of the Center's mediation
services.
7.4. The parties agree to continue performing their duties under this contract, which are
unaffected by the dispute, during the negotiation and mediation process.
2
8.1. Notice to be effective under this contract must be in writing and received by the
party against whom it is to operate. Notice is received by a party: (1) when it is delivered to the
party personally; (2) on the date shown on the return receipt if mailed by registered or certified
mail, return receipt requested, to the party's address specified in paragraph 8.2 and signed on
behalf of the party; or (3) three business days after its deposit in the United States mail, with
first -class postage affixed, addressed to the party's address specified in paragraph 7.2.
8.2. CAPCO's address is 2512 IH -35, South, Suite 220, Austin, TX 78704, Attention:
Betty Voights, Executive Director. The City's address is 221 E. Main Street,
Round Rock , Texas 78664, Attention: Bob Bennett, City Manager.
8.3. A party may change its address by providing notice of the change in accordance
with paragraph 8.1.
9.1. Each individual signing this contract on behalf of a party warrants that he or she is
legally authorized to do so and that the party is legally authorized to perform the obligations
undertaken.
9.2. This contract states the entire agreement of the parties, and an amendment to it is not
effective unless in writing and signed by all parties.
9.4. This contract is binding on and inures to the benefit of the parties' successors in
interest.
CITY OF ROUND ROCK, T
By
9.5. Sanborn is a third -party beneficiary of this contract.
9.6. This contract is executed in duplicate originals.
ayor
ax el
Date 02 3- 03
Art. 8 Notice to Parties
Art. 9. Miscellaneous
By
3
CAPITAL AREA P ANNING COUNCIL
11 17 tty Voit� s
Executive irector
Date
cfZ7
24 inch pixel B&W Orthophoto
$
37.37
Per sq. mile
24 inch pixel Color Orthophoto
$
41.59
Per sq. mile
24 inch pixel Color Infrared Orthophoto
$
43.05
Per sq. mile
24 inch pixel Multispectral Orthoimage
$
NO BID
Per sq. mile
12 inch pixel B &W Orthophoto
$
199.32
Per sq. mile
12 inch pixel Color Orthophoto
$
217.49
Per sq. mile
12 inch pixel Color Infrared Orthophoto
$
226.87
Per sq. mile
12inch pixel Multispectral Orthoimage
$
NO BID
Per sq. mile
6 inch pixel B&W Orthophoto
$
500.43
Per sq. mile
6 inch pixel Color Orthophoto!*
;$;
:585.13:
,Per sq. mile':
6 inch pixel Color Infrared Orthophoto
$
595.09
Per sq. mile
6 inch pixel Multispectral Orthoimage
$
NO BID
Per sq. mile
10' Contours from 24 inch pixel imagery DEM'sIDTM's
$
56.02
Per sq. mile
5' Contours from 12 inch pixel imagery DEM's /DTM's
$
296.08
Per sq. mile
2' Contours from 6 inch pixel imagery DEM's /DTM's
$
952.37
Per sq. mile
Updated 2' Contours from 6 inch pixel imagery DEM'sIDTM's
$
952.37
Per sq. mild
Updated 100 map scale planimetrics from 6 inch pixel imagery;
$ 11,822.65,
Per sq. mile
Capital Area Planning Council
APCOO Update
ee Schedule.. -City of Round Rock
;
As requested by the RFP, Section 6 2, and Sanborn Colorado's Proposal, Section 5, the following table of
s ervice options indicates the services selected by the Ciityof Round Rock
Square Miles
20.83
Task
Ortholplanitopo
Fee
$3,360.15
Total Fee
$69,991.92
Pncing Notes:
1. See the attached Statement of Work for detailed specifications, deliverables, fee and
production schedules and map area calculations and diagrams.
I Includes the fee to mosaic the entire Gty image database into the MrSID format using the updated tiles.
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Confidential and Pmpauay. 02002T. Sanborn Map Company. t. ALI RIGHTS RESERVED
Capital Area Planning Council _s2
CAPCO — City of Round Rock
Statement of Work
• The following scope of work is in response to a request for services by
CAPOO /Gty of Round Rock from Sanborn Colorado, L.L.C. The services
include production as follows:
• Produce first generation 6" pixel resolution color orthophotography of the Clty
of Round Rock (approximately 20.83 square miles) according to the attached
shape file printout and area calculation labeled Attachment A.
• Update 2' contour data of the Gty of Round Rock (approximately 20.83 square
m il's ; Attachment A).
• Update and compile pl<animetric data of the Qty of Round Rock
(approximately 20.83 square miles; Attachment A).
• Compress the new orthoimagery with the existing database in MrSID format.
The following services will be performed to support the project:
• Acquisition of Color aerial photography at 1" =600'
• Panel existing ground control point locations and establish new control points
as necessary (pre- marked or photo-identifiable features)
• Acquisition of AGPS data during the photography missions to supplement the
ground control network
• Scanning of the film negatives at a scan resolution of 14 microns
• Aerial Triangulation implementing softcopytechniques
• Softcopystereo compilation of LIDAR DTM and planimetric data
• Database design developed in conjunction with CAPCO /Qty of Round Rock
(from Gty of Round Rock 2001 database design)
Procedures
Sanborn will acquire color aerial photography at a negative scale of 1" =600' along an
optimal flight line pattern The aerial photography mission will be flown in spring 2003.
Prior to initiating the aerial photography mission, a proposed flight line map will be
developed using digital boundaries provided byCAPCO /Gty of Round Rock. The
flight plan will be submitted to the Gty of Round Rock's Project Manager for approval
prior to initiating the aerial photography mission. The aerial mission will proceed upon
receipt of Qty of Round Rock's signed approval/authorization to proceed.
The film negatives will be reviewed prior to scanning. The film will be examined for
scratches, marks, artifacts, overall quality, scale, crab, tilt, overlap, sidelap, and adherence
to the flight plan. Upon approval, the film will be scanned at 14 microns on Z/I
PhotoScan scanners. Scanning resolutions will be appropriate to meet output
requirements for the ground spatial distance (GSD) of the orthophotos. A pre -scan
analysis will be performed to facilitate the generation of image histograms and
correlation between negatives.
CAPCO Ortho Update: Fee Schedule - City of Round Rock 2
umacianua and cams.,. lc. ALL RIGHTS RESERVED
Capital Area Planning Council
Sanborn will use a combination of conventional ground control augmented by airborne
GPS (AGPS) data to control the FAAT. Sanborn will maximize the use of existing
ground survey stations as control and checkpoints for the generation of
orthophotographs. Suitable existing NSRS geodetic control will be used, supplemented
where necessary by new semi - permanent ground control points. Ties will be made to
existing Order B (two or more) and First Order horizontal control, and to vertical
control of suitable (Second Order or better) quality, to ensure conformity with the
specified datums (NAD83 and NAVD88). Vertical control will be established via a
combination of Second Order d;Piral geodetic leveling and First Order GPS surveys.
Final coordinates will be provided on the Texas Plane Coordinate System, Central Zone
in units of the U.S. Survey Foot.
Upon completing CAPCO project's ground control phase, Sanborn will prepare and
submit a final Survey Report. A Control Diagram will also be prepared which will
address all existing and newly established control used as a basis for the subsequent
photogrammetric work.
Digital orthophotographywill be produced by digitally scanning the color aerial
photography. Each image will be resected to simulate its position in space at the time of
exposure. The DTM will be applied to the raster file to differentially rectify the image to
eliminate distortion. Once the imagery has been rectified, it will be structured and
formatted in a seamless image database and re- sampled to the appropriate resolution.
The final deliverable will be images in tiled GeoTIFF format with world files.
Fully analytical aerial triangulation will be performed on the new photography and
control to support Softcopy compilation. The existing DTM and planimetrics will be
updated using Softcopy compilation methods.
The LIDAR DTM was collected for the City of Round Rock area during spring 2001.
The MAR DTM will be updated as necessary to support the generation of the updated
2' contours. All LIDAR procedures used by Sanborn will comply with FEMA
guidelines. Contour lines will be developed in accordance with the contour guidelines
for 1" =100' scale topographic maps. Every fifth contour line is an index contour and is
distinguished using a heavier line style to enhance identification. All contour lines are
solid and unbroken upon generation and will only be broken in client specified
locations. Where the ground is obscured by vegetation, the contours are dashed, which
indicate application of less strict accuracy criteria. Elevation values are assigned to the
contour lines and carried as attributes.
Spot elevations will be indicated at the following locations:
• Road intersections and the road centerline at the abutment and center of
bridges and over all major culverts
• Road/railroad intersections
• Surface water elevations and intersection points of all tributaries and main
channel
• Crest of significant closed contours
• Lowest point of significant closed depression contours, saddles, and cuts
• Areas of dense vegetation where the ground is visible
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Canaan. and Hopi.Ary.02902 TN Sean, Map Compe y. Inc. ALL RIGHTS RESERVED
3
Feature
Paved roads (edge of pavement)
% Capture
City of Round Rock
(1" =100' map scale)
100
Paved parking (10 cars or more)
100
Paved driveway ( >150 ft.)
98
Paved alley
98
Unpaved roads (public, maintained)
98
Unpaved alleys
98
Trail centerlines (hike & bike)
95
Public sidewalks
100
Buildings ( >100 sq. ft., commercial if >4000 sq.
ft.)
98
Building spot heights (commercial & industrial)
98
Lake ( >5 acres) •
100
River ( >10 ft, double sided)
100
Drain ( <10 ft., single line)
95
Pond (> 1 acre)
98
Concrete Drain
98
Hidden Drain
95
Bridge
100
Culvert
95
Obscurred area
98
Capital Area Planning Council
The City of Round Rock 1" =100' Map Scale Planimeuic features will be updated using
the spring 2003 1" =600' negative scale photography. The feature capture rates (%
completeness) are listed below.
Accuracy Specifications
The accuracy specifications for the project will be as follows:
• ASPRS Class 1 AccuracyStandards for Large Scale Maps (1" =100' map scale)
• FEMA LiDAR specifications (See Attachment B).
Data that fails to meet project acceptance criteria are reworked in APS and Arclnfo.
Deliverables
• Project Initiation Phase
• Conversion Work Plan (preliminary and final)
• Aerial PhotographyPhase
• Flight line plan and control diagram
Aerial film negatives
• One set of all digital scans on CD or DVD
• Survey Control Phase
• Control diagram
CAPCO Ortho Update: Fee Schedule - City of Round Rock
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4
Capital Area Planning Council
Acceptance Criteria
The following guidelines establish the Acceptance Criteria between Sanborn and
CAPOO /Qty of Round Rock. The review period is subject to an acceptance rating in a
unit of delivery (i.e. tile). Sanborn divides the acceptance criteria into 3 distinct
categories; each of which is subject to an acceptance rating that we base on the total
number of features e.g., database attributes in a unit of delivery (Le. tile). The three
categories of acceptance criteria are, (1) data accuracy, (2) orthophotographyaccuracy,
and (3) review periods.
1. Data Accuracy:
(a) Data Base Design
Sanbom is responsible for achieving 100.0 percent accuracy when comparing
compliance between the files /database and the database design/scheme specifications
and all the topological system requirements (computer checkable). These requirements
are system specific and necessitate a list of details, such as,
• inclusively, the database record is all features that the database design/scheme
defines as having a database record;
• the database record includes only correct database relationships;
• features (data elements) correspond to a specific database record;
• attributes populate with [legal] value ranges;
• location of data within the map extent; and
• precision, fuzzy, and dangle tolerances are specific.
Edge - Matching:
(b)
CAPCO Ortho Update: Fee Schedule - City of Round Rock
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• One hard copy and one digital (ASCII) file of the report outlining results of
the ground Global Positioning Satellite observations
• GPS observations, results, observation logs, and data analysis and
adjustments
• Aerial Triangulation Phase
• One copy of FAAT Report
• Digital Orthophoto Phase
• One set of digital orthophotographyin TIFF /TFW format on CD orDVD
•• One set of compressed digital orthophotographyin MrSID format on CD
or DVD
• Photograrmnetric Compilation Phase
• Preliminaryphotogrammetric checkplots and Arc Info digital data
• Confirmation plots, as required
• Final photogranmetric plots on paper
• Digital Arc Info and AutoCAD files of planimetric and topographic data
• Data for DTM/DEM in ASCII file format
5
Capital Area Planning Council
Sanborn is responsible for achieving 100.0 percent accuracy when edgematching (i.e.,
graphic cross -tile connection) all linear features within a delivery area. The point (x,y) at
which a linear element crosses one tile, is the same value in the next tile.
(c) Snapping:
Sanborn is responsible for achieving 100.0 percent accuracy when snapping features that
are part of a topologically structured coverage (i.e., polygon), and 98.0 percent for non-
topologically structured linear features within 1 /1000' (.001 feet for 100 -scale mapping).
2. Orthophotography Accuracy.
Sanborn has developed a comprehensive Quality Asstuance (QA) Plan for measuring
the quality of digital orthophoto imagery. The QA Plan identifies specific standards and
criteria to determine an acceptance value for criteria including the following:
• Horizontal Image Accuracy- typically based upon the project accuracy
standards.
• Image Quality - depends on mosaicking , edgematching, foreign artifacts,
scratches, brightness, shadows, and contrast.
• Other Issues - radial displacement, water reflections, and system anomalies.
Sanborn has developed and published Digital Imaging Acceptance Criteria for
producing digital orthophotographyforthe CAPCO project. This document required
signatures of both Sanbom's and the Qty of Round Rock's Project Managers as an
agreement to the criteria to be applied during the production and QC of the
orthoimagery. Please refer to this document in Attachment C
3. Review Periods:
(d) CAPCO /Qty of Round Rock's Review Period:
CAPCO /Qty of Round Rock completes all computer checks or tests on the data within
30 days of receipt of the initial delivery. On or before 30 days, CAPCO /Qty of Round
Rock notifies Sanbom of the status of the file as either (1) accepted (2) received— edited
(returned to Sanborn for corrections), or (3) rejected (returned to Sanborn without a
complete edit). Any delivered tile that is found to exceed the error tolerances specified
herein within one year after project delivery will be corrected free of charge by Sanbom.
CAPCO /Qty of Round Rock may submit any failing tiles at the end of each calendar
quarter. Sanbom will correct and redeliver them within 30 - 60 calendar days.
(e) CAPCO /Qty of Round Rock's Rejected Products:
CAPCO /Qty of Round Rock reserves the right to reject the file in total, if, in
CAPCO /Qty of Round Rock's judgment, the file is unusable for the quality control edit
process, ie., and unreadable media.
(f) Sanbom's Review Period:
Sanborn validates and corrects all calls for redelivery of edited/rejected computer
checked digital files within 30 days of receipt from CAPCO /Qty of Round Rock.
Sanbom and CAPCO /Qty of Round Rock need to aim for a one -pass edit cycle. If
data requires a redelivery because of failing to meet the acceptance criteria, then Sanborn
corrects (for final deliver)) only those edit calls identified in the digital data file during
CAPCO /Qty of Round Rock's initial quality control data validation. Sanbom is
CAPCO Ortho Update: Fee Schedule - City of Round Rock
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Capital Area Planning Council
Invoicing and Payment Terms
Sanborn shall invoice monthly for percent complete. Payment terms for all valid
invoices received are NET30 from date of invoice.
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Confider. and Roplelery. 0 2002 ibe Sanborn Map Camp,. Inc. ALL RIGHTS RESERVED
responsible for achieving 100 percent accuracy for edit calls CAPCO /City of Round
Rock identifies.
(0 Acceptable Errors:
Errors falling within the acceptance criteria (under 2 percent), Sanborn will correct from
CAPCO /City of Round Rock edits for an additional fee (fee is according to the actual
hours required to correct and to process the data — per delivery unit.).
Production Schedule
Sanborn will commence work upon receipt of the signed work order from CAPCO.
Final data will be completed and delivered on or before September 30, 2003. Delivery of
final data is dependent upon actual date of acquisition of photography. Adjustments to
the production schedule will be made for any events that delayproduction.
7
Capital Area Planning Council
F EMA LIDAR Specifications
Guidelines and Specifications for Flood Hazard
Mapping Partners
Appendix A
Guidance for Aerial Mapping and Surveying
[February 2002]
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Ca * Instal l and Proprietary.* 2CO2 BarOm Map Company, Mc. ALL RIGHTS RESERVED
SAND RN-
A.1 Introduction
This Appendix presents Federal Emergency Management Agency (FEMA) aerial mapping and
surveying guidelines and specifications that have been established to specify the quality of the
spatial data products to be produced, including work maps and base maps used in the
production of Flood Insurance Rate Maps (FIRMs), Digital Flood Insurance Rate Maps
(DFIRMs), and DFIRM- Digital Line Graphs (DFIRM - DLGs). The term "FIRM" is used
generically hereinafter to specify this "family" of FEMA spatial products.
This Appendix also includes guidance for ground surveys of control points, cross sections, and
hydraulic structures; topographic mapping using photogrammetry, Llght Detection and
Ranging (LIDAR) or other airbome remote - sensing technologies, consistent with FEMA and
industry standards.
A.8 Airborne Light Detection and Ranging (LIDAR) Surveys
When Mapping Partners choose to use airborne LIDAR systems for gathering the data
necessary to create digital elevation data for hydraulic modeling of floodplains, digital terrain
maps, and other NFIP products, the guidelines and specifications presented in this section of
these Guidelines must be used
8
Capital Area Planning Council
[February 2002]
-42,1
LIDAR systems may not be able to gather all of the data necessary to create those products.
Data in areas such as bodies of water or dense forests may not meet the requirements of this
Appendix. For FEMA products containing such areas, the assigned Mapping Partner shall
supplement LIDAR data with data acquired by other means, as needed for hydraulic modeling.
Lesser standards may be applied for hydrologic modeling of watersheds or other studies.
The guidelines and specifications herein are to be used by FEMA Mapping Partners who use
LIDAR systems for data gathering purposes.
A.8.1 System Definitions
For the purpose of these Guidelines, LIDAR is defined as an airborne laser system, flown
aboard rotary or fixed -wing aircraft, that is used to acquire x, y, and z coordinates of terrain and
terrain features that are both manmade and naturally occurring. LIDAR systems consist of an
airborne GPS with attendant GPS base stations, Inertial Measurement Unit (IMU), and light -
emitting scanning laser.
The system measures ranges from the scanning laser to terrain surfaces within a scan width
beneath the aircraft. The time it takes for the emitted light (LIDAR retum) to reach the earth's
surface and reflect back to the onboard LIDAR detector is measured to determine the range to
the ground. Scan widths will vary, depending on mission purpose, weather conditions, desired
point density and spacing, and other factors.
The other two components of LIDAR systems are the airbome GPS, which ascertains the in-
flight three - dimensional position of the sensor, and the IMU, which delivers precise
information about the attitude of the sensor, i.e., the roll, pitch and heading.
[February 2002]
A.8.2 General Guidelines for Use
Two important factors in the LIDAR system mission planning are the point density of the
randomly spaced LIDAR points and the point spacing of the uniformly spaced DEM points
derived from the randomly spaced LIDAR returns. The correct point density necessary to
accurately represent terrain and terrain features will depend on flight conditions, mission
purpose, and required accuracy. As discussed in Sections A.3 and A.4, DEM point spacing of
5 meters or less and vertical accuracy of 1.2 feet at the 95- percecent confidence level
(Accuracy) is required for digital elevation data equivalent to 2 -foot contours for flat terrain,
and Accuracy of 2.4 feet is required for digital elevation data equivalent to 4' -foot contours for
rolling to hilly terrain.
Flight -path planning is another important factor in the LIDAR system mission. The flight path
shall cover the study area satisfactorily including both parallel and enough cross flight lines to
eliminate shadowing and allow for proper quality control.
CAPCO Ortho Update: Fee Schedule - city of Round Rock
CanMUgIW and Proprietary. 0 2CO2 The Sam Map CanWnY, Mc, ALL RIGHTS RESERVED
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Capital Area Planning Council
[February 2002]
[February 2002]
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Ceefidenfl.l and Pmpktary, 02002 The Sanborn Mk, C0119an,, Inc. ALL RIGHTS RESERVED
Unlike aerial photogrammetry, LIDAR missions can be flown without regard to sun angle.
Flights may take place at night, if conditions otherwise allow. However, it is recommended that
some form of imagery exist over the LIDAR area. Simultaneous video or digital imagery
cannot be acquired if LIAR data are acquired at night, but LIDAR intensity retums can be
acquired day or night, and these help to identify features during LIDAR post- processing.
Altematively, digital orthophotos acquired at a different time can be used for this purpose.
Elevation and measurement information related to subsurface channel and hydraulic structure
geometry shall be obtained through the use of other mapping technologies over deep or turbid
water. In some instances, shallow water and near -shore coastal surveys can be accomplished
using airborne LIDAR bathymetric systems equipped with lasers operating in portions of the
light spectrum that allow transmission through water.
LIDAR system tolerance for inclement weather conditions (e.g., high winds, wet snow, rain,
fog, high humidity, low cloud cover) generally is higher than that of photogrammetric methods.
However, such conditions have been known to degrade the accuracy of laser return data.
Therefore, Mapping Partners shall generally avoid missions during inclement weather.
High point densities may allow satisfactory data collection in areas of dense foliage. Still, care
shall be taken in planning missions with regard to both natural (vegetative) and manmade
(structure) ground cover. Pulse width, beam divergence, first and last pulse return
discrimination, and choice of the post - processing algorithms used for vegetation or structure
removal may all affect the accuracy of LIDAR- derived data in areas of dense foliage.
A.8.3 Performance Standards
The accuracy standards in Sections A.3 and A.4 of this Appendix also shall apply to NFIP
maps and map products derived from LIDAR systems. LIDAR - derived data shall have the
accuracy required to produce topographic maps and products that meet NSSDA.
FEMA is not aware of any existing LIDAR system performance standards. Current information
about LIDAR systems is available from ASPRS (See ASPRS, 2001), National Oceanic and
Atmospheric Administration (NOAA), National Aeronautic and Space Administration, U.S.
Army Corps of Engineers, LIDAR system manufacturers and venders, and private firms that
provide LIDAR system services. As professional or trade associations issue specifications and
standards, FEMA may adopt those standards and specifications and amend this Appendix.
A.8.3.1 Overall Standards
The assigned Mapping Partner shall furnish all necessary materials and equipment. The
assigned Mapping Partner also shall supply the supervisory, professional, and technical
services personnel required to manage, survey, document, and process all data associated with
10
Capital Area Planning Council
[February 20021
CAPCO Ortho Update: Fee Schedule - City of Round Rock
CanMnWal and PmpbMry,02002 1110 Scn.= Map Company. Inc. All RIGHTS RESERVED
LIDAR system mapping, scanning, and digital image processing. The assigned Mapping
Partner shall provide all deliverables in accordance with the contract or other agreement with
FEMA and the requirements in this Appendix.
DEM posting shall be the minimum allowed by the data and shall not exceed 5 meters. As
specified in Section A.3, Accuracy, shall normally be 1.2 foot (equivalent to 2 -foot contours)
in flat terrain and 2.4 feet (equivalent to 4 -foot contours) in rolling to hilly terrain.
A.8.3.1.1 Data Voids
For the purposes of this Appendix, areas not within two times the DEM posting of data points
are data voids. Data voids may occur from several different causes, including the following:
LIDAR pulses may be naturally absorbed by water bodies or areas recently covered with
asphalt. Such voids are normally considered to be unavoidable.
The LIDAR system may have malfunctioned for some reason.
• Heavy winds, flight navigation system (FMS) error or pilot error may have caused
"holidays" between flight lines.
• Data points may be intentionally removed as part of the bare -earth post - processing to delete
points that impinged on the tops of manmade structures or failed to penetrate dense
vegetation.
Data voids caused by system malfunctions or flight line holidays are unacceptable, requiring
new flights. Data voids caused by removal of LIDAR data points on manmade structures are
always acceptable. Data voids caused by removal of LIDAR data points on dense vegetation
are subject to additional guidelines, depending on whether or not the voids exist inside or
outside the floodplain for which hydraulic modeling is to be performed:
When data voids exist outside the floodplain, hydrologic modeling of the watershed can still be
performed acceptably by "filling" the voids through interpolation from surrounding points.
When data voids exist inside the floodplain, the cause of the data voids, the size of the voids,
and the location of the voids all have a bearing on whether additional ground surveys will be
required to "fill" the voids. For example, if the data voids are caused by dense mangrove or
sawgrass areas, supplemental ground surveys within such areas are not needed. These voids are
normally "filled" by interpolation from elevation points immediately surrounding the mangrove
or sawgrass areas. When small data voids of less than 1 acre are caused by removal of points in
other types of dense vegetation, similar interpolation procedures may be employed at the
discretion of the FEMA Lead.
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The principal scenario where additional ground surveys are required involves larger void areas,
normally larger than 1 acre, located in areas where representative cross sections must be cut. If
equally acceptable areas exist elsewhere to cut representative cross sections, the FEMA Lead
may decide that the additional expense is unwarranted for filling larger data voids by ground
surveys. This "judgment call" is roughly equivalent to photogrammetric mapping where the
photogrammetrist cannot see through the dense vegetation, determines areas to be "obscured,"
and maps the contours with dashed lines. In such cases, the photogrammetrist compiles
representative cross sections only where the bare earth terrain can be seen in stereo, and
performs ground surveys of additional cross sections only if alternative photogrammetrically
compiled locations for cross sections are determined to be unacceptable.
[February 2002]
A.8.3.1.2 Artifacts
Artifacts are regions of anomalous elevations or
oscillations and ripples within the DEM data
resulting from systematic errors, environmental
conditions, or incomplete post - processing. They
may result from malfunctioning sensors, poorly
calibrated instrumentation, adverse atmospheric
conditions, or processing errors. When artifacts
are not totally removed, the assigned Mapping
Partner shall provide an analysis of the effects of
the remaining artifacts on DEM accuracy. The
analysis shall include a description of the causes
(contributing sources) of the artifacts and a
description of the steps taken to eliminate them.
Again, imagery is helpful in identification of
artifacts. Figure A-4 shows examples of artifacts
that remain after automated post - processing and
prior to manual post- processing of LIDAR data. Since a major portion of post - processing costs
pertain to manual post - processing which could consume as much as 80 percent of the total
budget for a LIDAR project, the FEMA Lead may decide that it is not cost effective to require
the bare -earth digital terrain data to be 100 percent clean and free of artifacts. As with data
voids, the severity of such artifacts depends upon their size and location. In fact, the removal
of such artifacts would create new data voids; therefore the guidelines are essentially identical.
Artifacts outside the floodplain, but inside the watershed, have no bearing on hydraulic
modeling and can be neglected. Often, LIDAR cross sections can be "cut" in areas other than
where the artifacts remain; and additional ground surveys are required only if necessary to
"cut" cross sections through such artifact areas.
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Figure A -4 Example of Artifacts
The exception to this policy is in the event that the Mapping Partner needs DEMs to be 100
percent clean of artifacts for reasons other than hydraulic modeling (e.g., for community GIS
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[February 2002]
[February 2002]
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requirements). In such cases, other criteria must be applied to justify the additional costs for
removal of all artifacts.
A.8.3.1.3 Outliers
During the RMSE calculation process in which survey checkpoints are compared to the
interpolated TIN values, for example, discrepancies may exist between the two values. Some of
the discrepancies may be larger than expected, especially in steep terrain or if a "blanket" of
dense vegetation such as mangrove, sawgrass, or dense wheat fields exists where the LIDAR
may accurately survey the top surfaces of such vegetation rather than penetrating to the ground;
in areas of complex topography (e.g., levees that look like hedge rows, boulders that look like
haystacks); or in forested areas where removal of the top canopy may yield a lower canopy of
underbrush that still does not represent the bare -earth terrain. If there are a limited amount of
larger than normal differences between the LIDAR interpolated elevations and the elevations
of surveyed checkpoints, this may have a significant impact on the final RMSE calculation.
Outliers often occur as a result of the failure to achieve a true bare -earth surface from the
vegetation removal process. A single outlier can override dozens or hundreds of accurate
checkpoints, making the entire RMSE value appear to be poor. When this occurs, the
coefficient of skew may indicate that the errors do not have a normal distribution, a sign that
the RMSE calculation may be misleading. (See Subsection A.8.6.3.4.) Having a large quantity
of outliers may highlight improper post processing. In order to deal with outliers, a criterion
may be established to remove a small percentage of the total number of checkpoints surveyed
which exhibit the largest discrepancies. Statisticians almost unanimously agree that errors
exceeding the "3- sigma" level are outliers; the "3- sigma" level provides confidence at the
99.75% confidence level, enabling only the worst 0.25% of a dataset to be discarded as
outliers. Less stringent criteria consider the discarding of the worst 1 %, 5% or 10% of the data.
Allowing 10% outliers would be in accord with the traditional National Map Accuracy
Standard where the worst 1 O% of all checkpoints are treated as outliers that can be discarded,
regardless of size. The PO is free to consider the provision of a limited percentage of outliers,
especially if the skew calculation indicates that the dataset lacks a normal distribution. The
option to collect additional check points to replace the outliers may be considered.
A.8.3.2 System Calibration
LIDAR system components are most effectively tested and calibrated by the equipment
manufacturer. Therefore, the Mapping Partner shall provide FEMA with evidence of
manufacturer calibration.
In addition to evidence of manufacturer calibration of system components, the Mapping
Partner shall submit evidence that the total LIDAR system was calibrated prior to project
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initiation for the purposes of identifying and correcting systematic errors. Proper system
calibration requires repetitive overflight of terrain features of known and documented size and
elevation using flight paths similar to those that will be used in the study area. For some
projects, daily in -situ calibrations may be required.
[February 2002]
A.8.3.3 Flight Planning
Planning a flight path that considers all aspects of data collection is critical to the success of the
mission. An analysis of the project area, project requirements, topography, proximity to
restricted air space, and other factors will determine the flight path configuration. The mission
should include parallel flight lines and, for quality control purposes, at least one cross flight
line. The spacing between the flight lines will depend on the desired amount of sidelap
between swaths and the terrain.
The density and accuracy of data generated by different equipment vary widely. The assigned
Mapping Partner shall have the flexibility of providing a flight path to create the necessary
point density to meet the posting and accuracy requirements and minimize the occurrence of
data voids.
The assigned Mapping Partner shall check the Position Dilution of Precision (PDOP) in the
study area. The PDOP is an indicator of the positional accuracy that can be derived from the
current GPS satellite geometry, which varies continuously; the smaller the PDOP number, the
higher the data quality.
The assigned Mapping Partner shall document mission date, time, flight altitude, airspeed, scan
angle, scan rate, laser pulse rates, and other information deemed pertinent. For a sample
mission data recordation checklist, refer to Table A -4, which appears at the end of this
Appendix.
[February 2002]
A.8.3.4 Global Positioning System (GPS) Base Stations
The assigned Mapping Partner shall select the GPS base stations carefully to ensure reliable
differential processing of airborne GPS data. NGS recommends the simultaneous use of two
GPS base stations during the mission. Either public- or private - domain GPS base stations are
suitable for use for this purpose, provided they are within the acceptable GPS baseline limits.
Normally 20 kilometer baseline lengths are maximum for high- accuracy LIDAR surveys,
where the airbome GPS error component should contribute no more than 5 centimeters to the
vertical error budget.
Where possible, GPS base stations shall have ellipsoid heights to an accuracy of 2 centimeters
relative to the Continuously Operating Reference Stations or the High Accuracy Reference
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Network. The assigned Mapping Partner shall use high - quality, dual- frequency GPS receivers
and associated antennae at the GPS base stations.
[February 2002]
A.8.4 Accuracy Reporting Methodology
FGDC documented a common methodology for determining and reporting the accuracy of
horizontal and vertical coordinates for geodetic control points (survey monuments) in FGDC-
STD -007.1 and FGDC -STD- 007.2. Additional guidance is included in NGS -58 (NOAA,
1997).
[February 2002]
[February 2002]
A.8.5 Post - Processing of Data
For hydraulic modeling, the assigned Mapping Partner shall provide high - resolution, high -
accuracy, "bare- earth" ground elevation data. To restrict data to ground elevations only, the
Mapping Partner shall remove elevation points on bridges, buildings and other structures, and
on vegetation from the LIDAR- derived data. In addition to randomly spaced LIDAR points,
before and after removal of data associated with structures and vegetation, the assigned
Mapping Partner shall produce a bare-earth TIN as well as a DEM, with the minimum regular
point spacing, no greater than 5 meters, allowed by the data in eastings and northings. The
assigned Mapping Partner shall use TIN linear interpolation procedures when validating the
vertical accuracy of the elevation dataset. Accuracy assessments should normally be performed
on the TIN and not on the DEM which is a derived product of slightly lower accuracy.
Using digital orthophotos, stereo photogrammetry, or other source materials, the assigned
Mapping Partner shall produce breaklines for stream centerlines, drainage ditches, tops and
bottoms of streambanks, ridge lines, road crowns, levees, bulkheads, seawalls, road/highway
embankments, and selected manmade features that constrict or control the flow of water (e.g.,
curb lines). When merged with mass points, breaklines are used to enforce TIN triangle edges.
The assigned Mapping Partner also shall specify the sources and accuracy of breakline data.
Breaklines are not depicted for small culverts that pass under roads unless those culverts (or
ditches leading in and out of them) are visible on available imagery without the use of
photogrammetric stereo compilation which is normally too expensive for this purpose.
A.8.6 Quality Assurance /Quality Control
QA/QC of the LIDAR- derived data is primarily the responsibility of the assigned Mapping
Partner. This QA/QC process shall include reviews of flight alignments and completeness of
supporting data (e.g., cross sections, profiles). Until LIDAR technology and procedures
become mature, FEMA will normally provide funding for independent QA/QC testing.
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[February 2002]
A.8.6.1 Vertical RMSE Standards
When systematic errors have been corrected and remaining errors have a normal distribution,
the NSSDA uses the root mean square error (RMSE) to estimate both horizontal and vertical
accuracy. RMSE is the square root of the average of the set of squared differences between
dataset coordinate values and coordinate values from an independent source of higher accuracy
for identical points. If those differences are normally distributed and average zero, 95 percent
of any sufficiently large sample should be less than 1.96 times the RMSE. Therefore, vertical
RMSE of 18.5 centimeters is often referred to as equivalent to 2' contours, or "37- centimeter
accuracy at the 95- percent confidence level." Following that convention, the vertical accuracy
of any digital elevation dataset is defined as 1.96 times the RMSE of linearly interpolated
elevations in that dataset, as compared with known elevations from high accuracy test points.
For the NFIP, TINS (and DEMs derived therefrom) should normally have a maximum RMSE
of 18.5 cm, equivalent to 2' contours, in flat terrain; and a maximum RMSE of 37 cm,
equivalent to 4' contours, in rolling to hilly terrain. The Mapping Partner shall field verify the
vertical accuracy of this TIN to ensure that the 18.5 cm or 37.0 cm RMSE requirement is
satisfied for all major vegetation categories that predominate within the floodplain being
studied.
[February 2002]
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A.8.6.2 Ground Cover Categories
The assigned Mapping Partner shall separately evaluate and report on the TIN accuracy for the
main categories of ground cover in the study area, including the following:
1. Bare -earth and low grass (plowed fields, lawns, and golf courses);
2. High grass, weeds, and crops (hay fields, corn fields, and wheat fields);
3. Brush lands and low trees (chaparrals, mesquite);
4. Forested, fully covered by trees (hardwoods, evergreens, and mixed forests);
5. Urban areas (high, dense manmade structures);
6. Sawgrass; and
7. Mangrove.
Ground cover Categories 1 through 5 above are fairly common everywhere. FEMA experience
with Categories 6 and 7 is that sawgrass and mangrove each have vegetation so dense that
LIDAR pulses do not penetrate to the ground, but instead map the top reflective surface. The
assigned Mapping Partner must treat such areas like "obscured terrain" with conventional
photogrammetry whereby bare earth elevations within such vegetation category polygons can
only be estimated by interpolating elevations from ground points surrounding such polygons.
The assigned Mapping Partner may further subdivide and expand the above definitions to
better accommodate the predominant vegetation types in the study area. The assigned
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Capital Area Planning Council
-sm+
Mapping Partner shall distribute sample points throughout each category area being evaluated
and not group the sample points of the same type in a small sub -area.
The assigned Mapping Partner shall select a minimum of 20 test points for each major
vegetation category identified. Therefore, a minimum of 60 test points shall be selected for
three (minimum) major land cover categories, 80 test points for four major categories, and so
on. The Mapping Partner shall consider establishing test points when planning field surveys to
gather cross section data for hydraulic modeling. Confidence in the calculated RMSE value
increases with the number of test points and is a function of sample size. By specifying a
minimum of 60 checkpoints (20 each in three or more land cover categories), FEMA is
specifying that 60 test points are the minimum necessary for a practical level of confidence in
the calculated RMSE statistic but recognizing that a higher number of checkpoints will provide
higher confidence that performance standards have been achieved.
The test points are to be selected in terrain that is flat or uniformly sloped within 5 meters in all
directions. The uniform slope must not exceed 20 percent. The test points must never be
located near to breaklines, such as bridges or embankments. Test points on sloping or irregular
terrain would be unreasonably affected by the linear interpolation of test points from
surrounding TIN points and, therefore, shall not be selected.
[February 2002]
A.8.6.3 Analysis of Error Frequency Distribution
The RMSE process assumes that errors have a normal distribution (bell curve) with zero mean,
and that all systematic errors have been removed. This is rarely the case, especially with
LIDAR data. Some systematic errors or biases remain undetected, even after regular
calibrations of LIDAR systems. This Subsection addresses statistical processes for evaluating
whether the errors have a central tendency close to zero, evaluating the measure of general
variability, and evaluating the measure of skewness. Unfortunately, no hard and fast rules to
pinpoint problems exist, but each of the statistical processes mentioned have some value in
detecting the potential presence of systematic errors, for which further investigations are
warranted, especially if the RMSE calculation fails to pass the vertical accuracy criteria
established for the project.
[February 2002]
A.8.6.3.1 Histograms
The most common form of error analysis is to develop a histogram of all errors. If a dataset
tabulates errors for all checkpoints, a histogram might show how many of those errors fell
within different 5- centimeter ranges, for example, graphing the number of errors between the
following error values: - 50 cm, -45 cm, -40 cm, -35 cm, -30 cm, -25 cm, -20 cm, -15 cm, -10
cm, -5 cm, 0, +5 cm, +10 cm, +15 cm, +20 cm, +25 cm, +30 cm, +35 cm, +40 cm, +45 cm,
and +50 cm. Histograms illustrate whether the errors are unimodal, bimodal, or multimodal,
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-30 -25 -20 -15 -10 -05 0 +5 +10 +15 +20 +25
have small or large variability, or are skewed on either the positive or negative side. Often,
such histograms for LIDAR data appear to approximate a normal distribution, except that it
does not have a zero mean; this would appear to indicate the presence of uncorrected
systematic error. Separate histograms for individual land cover categories often depict
significantly different characteristics that help to understand LIDAR system performance
(including post - processing) in the different categories. Figure A -5 is an example of a histogram
reflecting checkpoint errors from a LIDAR dataset that does approximate a normal error
distribution.
[February 2002]
Figure A -5 Histogram for Checkpoint Errors in LIDAR Dataset
A.8.6.3.2 Measures of Central Tendency
Three common measures of the central tendency of errors in a dataset may be used to quantify
the nearness to or departure from the expected central tendency of zero:
• The Arithmetic Mean is the sum of all the errors, divided by the number (n) of checkpoints.
When the mean error is large, this is an indicator that systematic errors may be present.
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[February 2002]
• The Median is the value at which there are as many larger errors as there are smaller errors.
• The Mode is the value at which the greatest number of errors is concentrated. In a
histogram, the mode is the error value or error range which has the highest ordinate value at
the peak of the histogram.
A.8.6.3.3 General Variability
Various measures of general variability for statistical data exist, including range, average deviation,
RMSE, standard deviation, and variance. However, the Industry standard for geospatial data is the
RMSE explained in Sections A.2 and A.3. For the dataset used to compute the histogram in Figure A -5,
the RMSE =11.7- centimeters which equates to vertical Accuracy: of approximately 22.9 - centimeters at
the 95- percent confidence level. The standard deviation (a or sigma) is primarily used for determination
of statistical outliers, I.e., elevation errors that exceed the 3 -sigma level.
[February 2002]
A.8.6.3.4 Skewness
Skewness is the condition of being asymmetrical or lopsided, and departing from the expected
normal distribution shown by the "bell curve." The coefficient of skewness (a unitless number)
is used to compute the asymmetry of the errors about the arithmetic mean error. When the
absolute value of the skew exceeds 0.5, this means that the error distribution is asymmetrical
and may not represent a normal distribution. The Mapping Partners should investigate all
datasets with skew values exceeding ±0.5 to determine if there is a valid reason why the errors
do not have a normal distribution (a basic assumption in calculation of RMSE values). For the
dataset used to compute the histogram in Figure A -5, the skew is 0.429. The skew is computed
automatically by Microsoft Excel and other spreadsheets, and uses calculations of the second
and third central moments of the dataset.
The coefficient of skew is zero when the error distribution is perfectly symmetrical.
[February 2002]
A.8.6.4 Error Assessment
When a LIDAR dataset does not pass the vertical accuracy standard, steps must be taken to
identify the cause of the errors. Systematic corrections should never be applied without first
identifying the cause of errors. Many factors could have contributed to errors, including the
following:
• The LIDAR aircraft may have flown at too high of an altitude, causing IMU angular errors
to propagate to larger errors on the ground from a higher altitude.
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• The GPS baselines may be too long, flying too far from the GPS base stations, and causing
larger than normal errors in airborne GPS positions.
The scan angle may have been too large or the airspeed too fast, causing wider point
spacings and fewer laser pulses that were near vertical.
• The satellite PDOP may have been too high, reducing the accuracy of airborne GPS
positions.
• The post - processing algorithms may have been applied incorrectly.
• There may have been systematic errors with the airbome GPS, IMU, or laser scanner.
The list of potential causes is a long one because the process is complex.
Many of the statistical tools described in Subsection A.8.6.3 may point to the apparent
existence of systematic errors. The following are standard procedures to be used by FEMA's
Mapping Partners to "trouble shoot" total LIDAR systems in order to isolate systematic errors:
[February 2002]
A.8.6.4.1 Assessments by Land Cover
If ground cover category 1 (bare earth, sand, rock, dirt, short grass) does not pass the vertical
accuracy standard, the potential causes are different from potential causes when vegetated or
urban areas do not pass. Ground cover category 1 essentially should always pass accuracy
standards, unless something systematic is wrong. Daily calibration tests help to confirm that
the system performed well at the calibration test site (on that same day with the same sensor),
and the calibration site normally includes bare earth terrain and short grasses. If ground cover
categories 3 or 4 (see Subsection A.8.6.2) alone do not pass the vertical accuracy standard, the
most probable causes are shortcomings in the vegetation - removal procedures used in post -
processing. If ground cover category 5 (urban terrain) does not pass, something systemic about
urban buildings may cause the errors.
[February 2002]
A.8.6.4.2 Assessments by Error Locations
The Mapping Partner shall assess errors relative to their location within flight lines, or near the
beginning or end of swaths. This may indicate IMU errors or high satellite residuals due to
aircraft banking causing cycle slips and multipath.
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A.8.6.4.3 Assessments by Dates /Sensors
When LIDAR datasets are flown on different dates, or with different sensors, the Mapping
Partner must consider these variables in the error analyses.
[February 2002]
A.8.6.4.4 Airborne GPS Verification
The Mapping Partner shall examine GPS flight trajectories, compare the forward and reverse
flight trajectories' combined separation, check satellite health, check geo- magnetic
observations, and verify the following:
• PDOP;
• GPS satellite residuals;
• Satellite phase RMS;
• Weighting adjustments when two or more differential base stations are used;
• Base station distance separation;
• Position standard deviations;
Vertical datum used; and
• Correct application of Geoid99 calculation of orthometric heights.
[February 2002]
A.8.6.4.5 Inertial Measurement Unit (IMU) Verification
The Mapping Partner normally shall do the following to verify the accuracy of the IMU:
• Review the Kalman filter, the measurement residual ratio (MRR), and the consecutive
measurement rejections settings;
• Confirm IMU was in "fine align" mode for the whole of the dataset;
• Check accelerometer drift and scale factor, and the gyro drift and scale factor to ensure they
are within specifications;
• Compare GPS trajectory with recomputed IMU trajectory and investigate large
discrepancies; and
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• Review IMU to lever arm parameter measurements and ensure they are entered correctly in
the proper reference system.
[February 2002]
A.8.6.4.6 Laser Range Verification
The Mapping Partner shall normally do the following to verify the accuracy of the laser ranges:
• Review raw laser ranges;
• Identify areas of high dropouts (no returns) and correlate them to justifiable features;
• Review scanner mirror angles (galvanometers or micro- controller);
Examine intensity images if collected; and
• Review system generated error log sheets.
[February 2002]
A.8.6.4.7 Total System Verification
To verify the accuracy of the whole system, the Mapping Partner shall do the following:
• Review calibration flights and compare to system flight parameters;
• Use CAD software to analyze individual flightlines and verify pitch, roll and heading
errors;
• Check overlap for roll and scaling errors;
• Check ground features for pitch (i.e., buildings, bridges, etc.);
Check scaling errors if water bodies exist;
• Compare cross flight data for attitude; and
• Verify vegetation removal procedure and review parameters if data were "corrected" or
adjusted for pitch, roll and heading errors; for example, was the iteration angle too high for
the terrain type? Is the morphological window within a reasonable size for area features
(e.g., is it too large and removes key components such as large dunes ?).
[February 2002]
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A.8.6.4.8 Systematic Error Corrections
It is relatively easy to determine the magnitude of systematic errors and adjust all data
accordingly, however, the assigned Mapping Partner must not be "correct" such errors until the
error source is clearly identified and documented. The Mapping Partner must report systematic
errors to the FEMA Lead for review before systematic reprocessing of data that initially failed
to pass the accuracy criteria.
[February 2002]
A.8.6.5 Cross Flight Verification
To supplement the QA/QC process for LIDAR data, the Mapping Partner may employ
different optional techniques to check not only the accuracy but also the precision. The balance
is to address the need for additional verification checkpoints with cost - effective methods that
aid in identifying the internal consistency (precision) of LIDAR data. Two GPS techniques that
may be utilized are continuous kinematic and Real Time Kinematic (RTK). Continuous
kinematic collects positional data every epoch while maintaining fixed ambiguities on a
minimum of five satellites. In the event of loss of lock on satellites, the integer ambiguities
must be recomputed to their fixed integer value_ before a sub decimeter position can be
calculated. Post processing is required to obtain the positional data. RTK is similar to
continuous kinematic except that the data do not need to be post - processed. The estimated
ambiguities are fixed to their integer values and positional data are calculated and stored in real
time. Both methods are efficient for GPS surveys along highways.
With both types of GPS procedures the process is to survey checkpoints perpendicular to the
LIDAR flight paths at different strategic locations, with these additional checkpoints along
roads or highways that transect the survey area. The assigned Mapping Partner shall conduct
surveys close to the center of roads and highways, but avoiding bridges, elevated roads, or
roads with steep embankments so that LIDAR points can be interpolated accurately without
concern for steep slopes. If the flights are flown north to south, then the checkpoints must
traverse east and west across the project area. A minimum of three cross lines must be
measured, one at each end of the flight lines and another through the center. Typically the
weakest data will be at the beginning of the flight line if the GPS and IMU have not stabilized
due to the turning of the aircraft. The center cross line will help identify if the airborne data are
stabilized. Ideally checkpoints should have a minimum point spacing of one half the LIDAR
swath width to ensure each swath has at least one checkpoint. Increasing the number of cross
flight checkpoints will assist in verifying confidence within the data. Because such surveys are
less accurate than the surveys of checkpoints to NGS -58 5- centimeter standards, these
additional verification points are not to be mixed with the survey checkpoints used to compute
the vertical RMSE or Accuracy,. However, this is a relatively inexpensive way to generate a
relatively large number of somewhat less - accurate checkpoints when there is concern that the
60, 80 or 100 checkpoints (20 each in the major land cover categories) are insufficient for
providing a high degree of confidence in the accuracy statistics.
[February 2002]
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A.8.7 Deliverables
All data and products associated with contract deliverables shall meet or exceed relevant
NSSDA standards and fully comply with the FGDC metadata format standard with the
provisions in the contract. The Mapping Partner shall use Appendix I of these Guidelines as a
guide for preparing and submitting deliverable products to FEMA in digital format.
[February 2002]
A.8.7.1 Pre - Project Deliverables
Prior to data collection, the Mapping Partner shall submit the following to the FEMA Lead or a
Mapping Partner designated by the FEMA Lead:
A map showing the study area boundaries and flight path, at a medium scale (1:24,000) or
small scale (1:50,000); typically, USGS maps are desirable for this purpose
• Documentation specifying altitude, airspeed, scan angle, scan rate, LIDAR pulse rates, and
other flight and equipment information deemed appropriate; and
A chart of areas of high PDOP, or a list showing the time of the beginning and end of high
PDOP.
[February 2002]
A.8.7.2 Post - Project Deliverables
Following project completion, the Mapping Partner shall submit the following to the FEMA
Lead or a Mapping Partner designated by the FEMA Lead:
• A LIDAR system data report;
• A flight report;
• A ground control report;
• Data processing procedures for selection of postings, and all orthometric values of x, y, and
z coordinates for LIDAR returns. Elevations shall be orthometric heights; and
• A system calibration report.
The LIDAR system data report shall include discussions of the following:
• Data processing methods used, including the treatment of artifacts;
• Final LIDAR pulse and scan rates;
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• Scan angle;
• Capability for multiple returns from single pulses;
• Accuracy and precision of the LIDAR data acquired;
Accuracy of the topographic surface products;
• Any other data deemed appropriate;
• Companion imagery, if any; and
• A digital spatial index showing the orientation of all data tiles within the project site with
tile labels corresponding to the CD (or other media) ID and file name on that CD.
The flight report shall document mission date, time, flight altitude, airspeed, and other
information deemed pertinent. The report shall include information about GPS- derived flight
tracks, provide a detailed description of fmal flight line parameters and GPS controls (i.e.,
benchmarks), and include ground truth and complementary reference data.
The ground control report shall include, at a minimum, all pertinent base station information
and mission notes, including information on GPS station monument names and stability.
[February 2002]
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Con idemlal and PmRlelery.02002 The S.to.n Map COmpeny, Inc., ALL RIGHTS RESERVED
A.8.7.3 Delivery of Digital Data
In addition to the pre- and post- project deliverables described above, the Mapping Partner shall
submit the following:
• All raw datasets, dataset of survey points filling voids, dataset of transects (if generated),
bare -earth DEM data, and brealdines in separate data files; and
• Uniformly spaced DEM(s), on ISO 9660 standard CD -ROM (or DVD) media in a format
specified in Appendix L.
The Mapping Partner shall deliver raw datasets and LIDAR system data, including orthometric
heights for each point, in comma - delimited ASCII files in x, y, and z format. The Mapping
Partner shall deliver the DEM in the format designated on the Table A-4 checklist. The
Mapping Partner also shall flag raw datasets from sidelap and overlap areas of separate flight
lines. Brealdines shall be produced, and breakline files shall contain a flag record that
identifies them as breakline features and identifies their source and accuracy. The Mapping
Partner shall submit raw datasets in tiles or data models matching those of the DEM.
The Mapping Partner shall ensure that all deliverables conform to the projection, datum, and
coordinate system specified in the agreement with FEMA. File sizes cannot exceed 1 gigabyte,
25
Capital Area Planning Council
unless otherwise specified by the FEMA Lead. Each file shall be organized to facilitate data
manipulation and processing.
[February 2002]
A.8.8 Acceptance /Rejection
The terms of acceptance/rejection in Section A.7.5.5 of this Appendix shall apply.
*Denotes Minimum Required Information
CAPCO Ortho Update. Fee Schedule - City of Round Rock
Confidential W P,OelMery.02002 TT. SWOOm Map Company. ht. ALL RIGHTS RESERVED
26
RESOLUTION NO. R- 03- 02- 13 -13B1
WHEREAS, Chapter 791 of the Texas Government Code, V.T.C.A.,
authorizes local governments and agencies of the state to enter into
agreements with one another to perform governmental functions and
services, and
WHEREAS, the City of Round Rock wishes to enter into an
Interlocal Contract for Orthophotography with the Capital Area Planning
Council for Aerial Photography Updates of selected high growth areas in
and around the City, Now Therefore
BE IT RESOLVED BY THE COUNCIL OF THE CITY OF ROUND ROCK, TEXAS,
That the Mayor is hereby authorized and directed to execute on
behalf of the City an Interlocal Contract for Orthophotography with the
Capital Area Planning Council, a copy of said Contract being attached
hereto as Exhibit "A" and incorporated herein for all purposes.
The City Council hereby finds and declares that written notice of
the date, hour, place and subject of the meeting at which this
Resolution was adopted was posted and that such meeting was open to the
public as required by law at all times during which this Resolution and
the subject matter hereof were discussed, considered and formally acted
upon, all as required by the Open Meetings Act, Chapter 551, Texas
Government Code, as amended.
RESOLVED this 13th day of Februar
CHRISTINE R. MARTINEZ, City Secreta
OAwda,, \RESOLIIII \R30]1391.NPO /ac
2
0
WELL, Mayor
Ci of Round Rock, Texas
CAPITAL AREA PLANNING COUNCIL
INTERLOCAL CONTRACT FOR ORTHOPHOTOGRAPHY
Art. 1. Parties and Purpose
1.1. The Capital Area Planning Council ( "CAPCO ") is a regional planning commission
and political subdivision of the State of Texas organized and operating under the Texas Regional
Planning Act of 1965, as amended, chapter 391 of the Local Government Code.
1.2. The City of Round Rock (the "City") is a Texas home -rule municipality that is
seeking to obtain orthophotography mapping services.
1.3. CAPCO has contracted with Sanborn Colorado L.C.C. ( "Sanborn ") to provide
orthophotography services. This contract is entered into between CAPCO and the City under
chapter 791 of the Government Code so that the City can contribute to the cost of CAPCO's
contract with Sanborn and Sanborn can provide the City with additional orthophotography
mapping.
Art. 2. Goods and Services
2.1. CAPCO agrees to furnish the City the orthophotography mapping prepared by
Sanborn for the City under its contract with CAPCO. The orthophotography mapping
specifications and timetable for delivery are described in the Attachment to this contract.
Art. 3. Contract Price and Payment Terms
3.1. The City agrees to compensate CAPCO in the total amount of not to exceed $69,992
for goods and services furnished the City under this contract. The City represents that it has
current revenues available on the effective date of this contract to make all payments required by
this contract.
3.2. The City agrees to pay CAPCO the total contract price in installments as work is
completed and invoiced.
3.3. CAPCO agrees to invoice the City for the payments when due under paragraph 3.2,
and the City agrees to pay CAPCO the invoiced amount within 30 calendar days from the date of
the invoice.
Art. 4. Effective Date and Term of Contract
4.1. This contract takes effect on the date it is signed on behalf of CAPCO and it ends,
unless sooner terminated under Art. 6, on September 30, 2003.
EXHIBIT
11A"
Art. 5. Nondiscrimination and Equal Opportunity
5.1. CAPCO and the City shall not exclude anyone from participating under this
contract, deny anyone benefits under this contract, or otherwise unlawfully discriminate against
anyone in carrying out this contract because of race, color, religion, sex, age, disability,
handicap, or national origin.
Art. 6. Early Termination of Contract
6.1. If CAPCO or the City breaches a material provision of this contract, the other may
notify the breaching party describing the breach and demanding corrective action. The breaching
party has five business days from its receipt of the notice to correct the breach, or to begin and
continue with reasonable diligence and in good faith to correct the breach. If the breach cannot
be corrected within a reasonable time, despite the breaching party's reasonable diligence and
good faith effort to do so, the parties may agree to terminate the contract or either party may
invoke the dispute resolution process of Art. 7.
6.2. If the City fails to pay CAPCO the full contract price set out in paragraph 3.1,
CAPCO and Sanborn jointly own with the City any goods and services provided the City but not
paid for. Joint ownership of these goods and services is automatically established among
CAPCO, Sanborn, and the City at the time of termination for nonpayment under paragraph 6.1
and continues until Sanborn is paid in full for the goods and services provided, at which time the
City becomes the sole owner of the goods and services.
6.3. Termination for breach under paragraph 6.1 does not waive either party's claim for
damages resulting from the breach,
Art. 7. Dispute Resolution
7.1. The parties desire to resolve disputes arising under this contract without litigation.
Accordingly, if a dispute arises, the parties agree to attempt in good faith to resolve the dispute
between themselves. To this end, the parties agree not to sue one another, except to enforce
compliance with this Art. 7, until they have exhausted the procedures set out in this Article.
7.2. At the written request of either party, each party shall appoint one nonlawyer
representative to negotiate informally and in good faith to resolve any dispute arising under this
contract. The representatives appointed shall determine the location, format, frequency, and
duration of the negotiations.
7.3. If the representatives cannot resolve the dispute within 30 calendar days after the
first negotiation meeting, the parties agree to refer the dispute to the Dispute Resolution Center
of Austin for mediation in accordance with the Center's mediation procedures by a single
mediator assigned by the Center. Each party shall pay half the cost of the Center's mediation
services. '
7.4. The parties agree to continue performing their duties under this contract, which are
unaffected by the dispute, during the negotiation and mediation process.
2
Art. 8 Notice to Parties
8.1. Notice to be effective under this contract must be in writing and received by the
party against whom it is to operate. Notice is received by a party: (1) when it is delivered to the
party personally; (2) on the date shown on the return receipt if mailed by registered or certified
mail, return receipt requested, to the party's address specified in paragraph 8.2 and signed on
behalf of the party; or (3) three business days after its deposit in the United States mail, with
first -class postage affixed, addressed to the party's address specified in paragraph 7.2.
8.2. CAPCO's address is 2512 IH -35, South, Suite 220, Austin, TX 78704, Attention:
Betty Voights, Executive Director. The City's address is 221 E. Main Street,
Round Rock , Texas 78664, Attention: Bob Bennett, City Manager.
8.3. A party may change its address by providing notice of the change in accordance
with paragraph 8.1.
Art. 9. Miscellaneous
9.1. Each individual signing this contract on behalf of a party warrants that he or she is
legally authorized to do so and that the party is legally authorized to perform the obligations
undertaken.
9.2. This contract states the entire agreement of the parties, and an amendment to it is not
effective unless in writing and signed by all parties.
9.4. This contract is binding on and inures to the benefit of the parties' successors in
interest.
9.5. Sanborn is a third -party beneficiary of this contract.
9.6. This contract is executed in duplicate originals.
CITY OF ROUND ROCK, TEXAS CAPITAL AREA PLANNING COUNCIL
By By
Nyle Maxwell Betty Voights
Mayor Executive Director
Date Date
3
Capital Area Planning Council
CAPCO Ortho Update* Fee Schedule - City of Round Rock
Conde., en0 P.opRW,. e]OV[T.r Sen(•Y. n nc, ALL MOWS RESERVED
ate
of Round Rock
As requested bythe RFP, Section 6.2, and Sanborn Colorado's Proposal, Section 5, the following table of
service options indicates the services selected bythe Gtyof Round Rock
i�r r.lt�,�ffC�i'ur rt'i
fat je t'I tt� :�IFI 0 �i'y t 1F .
inch. ••I .Ir 0
i1"r�.,1(l ih . 0
12 inch pixel B &W Orthophoto
199.32 Per sq. mile
12 inch •ixel Color Ortho•hoto
217.49 Per s.. mile
12 inch • ixel Color Infrared Ortho. hoto
226.87 Per s.. mile
12inch •ixel Multis•ectral Orthoima.e
NO BID Per s.. mile
[0 0 1 6' rkIE SAY
10' Contours from 24 inch •ixel image DEM's/DTM's
56.02 Per s . mile
5' Contours from 12 inch .ixel image DEM's/DTM's
296.08 Per s.. mile
2' Contours from 6 inch •ixel image DEM's/DTM's
952.37 Per s•. mile
U•. ated 2' Contours from 6 inch •ixel imate DEM's/DTM's
952.37 Per s . mile
U• s ated 100 ma. scale .lanimetrics from 6 inch •ixel image
1,822.65 Per •. mile
Square Miles
20.83
Task
Ortho /plan/topo
Fee
$3,360.15
Total Fee
$69,991.92
Pncing Notes:
1. See the attached Statement of Work for detailed specifications, deliverables, fee and
production schedules and map area calculations and diagrams.
r Includes the fee to mosaic the entire City image database into the MrSID format using the updated tiles.
1
Capital Area Planning Council
CAPCO — City of Round Rock
Statement of Work
Procedures
• The following scope of work is in response to a request for services by
CAPOD /City of Round Rock from Sanborn Colorado, LL.0 The services
include production as follows:
• Produce first generation 6" pixel resolution color orthophotography of the Qty
of Round Rock (approximately 20.83 square miles) according to the attached
shape file printout and area calculation labeled Attachment A.
• Update 2' contour data of the Gty of Round Rock (approximately20.83 square
miles; Attachment A).
• Update and compile planirnetric data of the Qty of Round Rock
(approximately 20.83 square miles; Attachment A).
• Compress the new orthoimagery with the existing database in MrSID format.
The following services will be performed to support the project:
• Acquisition of Color aerial photography at 1" =600'
• Panel existing ground control point locations and establish new control points
as necessary (pre- marked or photo-identifiable features)
• Acquisition of AGPS data during the photography missions to supplement the
ground control network
• Scanning of the film negatives at a scan resolution of 14 microns
• Aerial Triangulation implementing softcopytechniques
• Softcopystereo compilation of LIDAR DTM and plani'„etric data
• Database design developed in conjunction with CAPCO /City of Round Rock
(from Qty of Round Rock 2001 database design)
Sanbom will acquire color aerial photography at a negative scale of 1" =600' along an
optimal flight line pattern. The aerial photography mission will be flown in spring 2003.
Prior to initiating the aerial photography mission, a proposed flight line map will be
developed Cuing digital boundaries provided by CAPCO /Gty of Round Rock. The
flight plan will be submitted to the Gty of Round Rock's Project Manager for approval
prior to initiating the aerial photography mission. The aerial mission will proceed upon
receipt of Qty of Round Rock's signed approval/authorization to proceed.
The film negatives will be reviewed prior to scanning. The film will be examined for
scratches, marks, artifacts, overall quality, scale, crab, tilt, overlap, sidelap, and adherence
to the flight plan. Upon approval, the film-will be scanned at 14 microns on Z/I
PhotoScan scanners. Scanning resolutions will be appropriate to meet output
requirements for the ground spatial distance (GSD) of the orthophotos. A pre -scan
analysis will be performed to facilitate the generation of image histograms and
correlation between negatives.
CAPCO Ortho Update: Fee Schedule - City of Round Rock
CmfdeNW and Propklary, 02002 The Satan Map Company, Inc., ALL RIGHTS RESERVED
2
Capital Area Planning Council
Sanborn will use a combination of conventional ground control augmented by airborne
GPS (AGPS) data to control the FAAT. Sanborn will maximize the use of existing
ground survey stations as control and checkpoints for the generation of
orthophotographs. Suitable existing NSRS geodetic control will be used, supplemented
where necessary bynew semi-permanent ground control points. Ties will be made to
existing Order B (two or more) and First Order horizontal control, and to vertical
control of suitable (Second Order or better) quality, to ensure conformity with the
specified datums (NAD83 and NAVD88). Vertical control will be established via a
combination of Second Order digital geodetic leveling and First Order GPS surveys.
Final coordinates will be provided on the Texas Plane Coordinate System, Central Zone
in units of the U.S. Survey Foot.
Upon completing CAPCO project's ground control phase, Sanborn will prepare and
submit a final Survey Report. A Control Diagram will also be prepared which will
address all existing and newly established control used as a basis for the subsequent
photogtarmnetric work.
Digital orthophotographywill be produced by digitally scanning the color aerial
photography. Each image will be resected to simulate its position in space at the time of
exposure. The DTM will be applied to the raster file to differentiallyrectifythe image to
eliminate distortion. Once the imagery has been rectified, it will be structured and
formatted in a seamless image database and re- sampled to the appropriate resolution.
The final deliverable will be images in tiled GeoTIFF format with world files.
Fully analytical aerial triangulation will be performed on the new photography and
control to support Softcopy compilation. The existing DTM and planimetrics will be
updated using Softcopycompilation methods.
The LIDAR DTM was collected for the Qty of Round Rock area during spring 2001.
The LIDARDTM will be updated as necessaryto support the generation of the updated
2' contours. All MAR procedures used by Sanborn will comply with FEMA
guidelines Contour lines will be developed in accordance with the contour guidelines
for 1" =100' scale topographic maps. Every fifth contour line is an index contour and is
distinguished using a heavier line style to enhance identification. All contour lines are
solid and unbroken upon generation and will only be broken in client specified
locations. Where the ground is obscured by vegetation, the contours are dashed, which
indicate application of less strict accuracy criteria. Elevation values are assigned to the
contour lines and carried as attributes.
Spot elevations will be indicated at the following locations:
• Road intersections and the mad centerline at the abutment and center of
bridges and over all major culverts
• Road/rallroad intersections
• Surface water elevations and intersection points of all tributaries and main
channel
• Crest of significant dosed contours
• Lowest point of significant closed depression contours, saddles, and cuts
• Areas of dense vegetation where the ground is visible
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Confidential end P 2002 he &ebwn M,p Company. Ix. ALL RIGHTS RESERVED
3
Feature
Paved roads (edge of pavement)
% Capture
City of Round Rock
(1" =100' map scale)
100
Paved parking (10 cars or more)
100
Paved driveway (>150 ft.)
98
Paved alley
98
Unpaved roads (public, maintained)
98
Unpaved alleys
98
Trail centerlines (hike & bike)
95
Public sidewalks
100
Buildings ( >100 sq. ft., commercial if >4000 sq.
ft.)
98
Building spot heights (commercial & industrial)
98
Lake ( >5 acres) •
100
River ( >10 ft, double sided)
100
Drain ( <10 ft., single line)
95
Pond (> 1 acre)
98
Concrete Drain
98
Hidden Drain
95
Bridge
100
Culvert
95
Obscurred area
98
Capital Area Planning Council
The Qty of Round Rock 1" =100' Map Scale Planimetric features will be updated using
the spring 2003 1" =600' negative scale photography. The feature capture rates (%
completeness) are listed below.
Accuracy Specifications
The accuracy specifications for the project will be as follows:
• ASPRS Class 1 AccuracyStandards forT arge Scale Maps (1" =100' map scale)
• FEMA LiDAR specifications (See Attachment B).
Data that fails to meet project acceptance criteria are reworked in APS and Anclnfo.
Deliverables
• Project Initiation Phase
•• Conversion Work Plan (preliminary and final)
• Aerial PhotographyPhase
• Flight line plan and control diagram
• Aerial film negatives
• One set of all diPlral scans on C) or DVD
• Survey Control Phase
• Control diagram
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Canfdeulal and Pmpluay, 0 2002171a Sanborn Map Company, Me, ALL RIGHTS RESERVED
4
Capital Area Planning Council
• One hard copy and one digital (ASCII) file of the report outlining insults of
the ground Global Positioning Satellite observations
• GPS observations, results, observation logs, and data analysis and
adjustments
• Aerial Triangulation Phase
• One copy of FAAT Report
• Digital Orthophoto Phase
• One set of digital orthophotographyin 11x1• /TFW format on CD orDVD
• One set of compressed digital orthophotography in MrSID format on CD
or DVD
• Photogrammetric Compilation Phase
• Preliminary photogrammetric checkplots and Arc Info digital data
• Confirmation plots, as required
• Final photogr ammetric plots on paper
• Digital Arc Info and AutoCAD files of planimetric and topographic data
• Data for DTM /DEM in ASCII file format
Acceptance Criteria
The following guidelines establish the Acceptance Criteria between Sanborn and
CAPCO /Qty of Round Rock The review period is subject to an acceptance rating in a
unit of delivery (Le. tile). Sanborn divides the acceptance criteria into 3 distinct
categories; each of which is subject to an acceptance rating that we base on the total
number of features e.g., database attributes in a unit of delivery (i.e. tile). The three
categories of acceptance criteria are, (1) data accuracy, (2) orthophotography accuracy,
and (3) review periods.
1. Data Accuracy.
(a) Data Base Design:
Sanborn is responsible for achieving 100.0 percent accuracy when comparing
compliance between the files /database and the database design /scheme specifications
and all the topological system requirements (computer checkable). These requirements
are system specific and necessitate a list of details, such as,
• inclusively, the database record is all features that the database design/scheme
defines as having a database record;
• the database record includes only correct database relationships;
• features (data elements) correspond to a specific database record;
• attributes populate with [legal] value ranges;
• location of data within the map extent; and
• precision, fuzzy, and dangle tolerances are specific.
(b) Edge - Matching:
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Con... and Proprietary.. .002 The Sanborn Map Company. Inc, ALL RIGHTS RESERVED
5
Capital Area Planning Council
Sanborn is responsible for achieving 100.0 percent accuracy when edgematrhing
graphic cross -tile connection) all linear features within a delivery area. The point (x,y) at
which a linear element crosses one tile, is the same value in the next tile.
(c) Snapping:
Sanborn is responsible for achieving 100.0 percent accuracy when snapping features that
are part of a topologically structured coverage (i.e., polygon), and 98.0 percent for non-
topologicallystructured linear features within 1 /1000' (.001 feet for 100 -scale mapping).
2. Orthophotography Accuracy:
Sanborn has developed a comprehensive Quality Assurance (QA) Plan for measuring
the quality of digital orthophoto imagery. The QA Plan identifies specific standards and
criteria to determine an acceptance value for criteria including the following:
• Horizontal Image Accuracy- typically based upon the project accuracy
standards.
• Image Quality- depends on mosaicking , edgematrhing, foreign artifacts,
scratches, brightness, shadows, and contrast.
• Other Issues - radial displacement, water reflections, and system anomalies.
Sanborn has developed and published Digital Imaging Acceptance Criteria for
producing digital orthophotography for the CAPCO project. This document required
signatures of both Sanbom's and the Qty of Round Rock's Project Managers as an
agreement to the criteria to be applied during the production and QC of the
orthoimagery. Please refer to this document in Attachment C.
3. Review Periods:
(d) CAPCO /Gty of Round Rock's Review Period:
CAPCO /Gtyof Round Rock completes all computer checks or tests on the data within
30 days of receipt of the initial delivery. On or before 30 days, CAPCO /Gtyof Round
Rock notes Sanborn of the status of the file as either (1) accepted (2) received— edited
(retumed to Sanborn for corrections), or (3) rejected (returned to Sanborn without a
complete edit). Any delivered tile that is found to exceed the error tolerances specified
herein within one year after project delivery will be corrected free of charge bySanbom.
CAPCO /Gty of Round Rock maysubmit any failing tiles at the end of each calendar
quarter. Sanborn will corde,i and redeliver them within 30-60 calendar days.
(e) CAPCO /Gtyof Round Rock's Rejected Products:
CAPCO /Gty of Round Rock reserves the right to reject the file in total, if, in
CAPCO /Gty of Round Rock's judgment, the file is unusable for the quality control edit
process, i.e., and unreadable media.
(f) Sanbom's Review Period:
Sanborn validates and corrects all calls for redelivery of edited/rejected computer
checked digital files within 30 days of receipt from CAPCC /Gty of Round Rock.
Sanborn and CAPCO/Qty of Round Rock need to aim for a one -pass edit cycle. If
data requires a redelivery because of failing to meet the acceptance criteria, then Sanborn
corrects (for final delivery) only those edit calls identified in the digital data file during
CAPCO /Gty of Round Rock's initial quality control data validation. Sanborn is
CAPCO Ortho Update' Fee Schedule - City of Round Rock
cam.. and PmMnurq, 0202Tinsanbom Map Company. hx., ALL RIGHTS RESERVED
6
Capital Area Planning Council
responsible for achieving 100 percent accuracy for edit calls CAPCO /Qty of Round
Rock identifies.
(g) Acceptable Errors:
Errors fallin within the acceptance criteria (under 2 percent), Sanborn will correct from
CAPCO /Qty of Round Rock edits for an additional fee (fee is according to the actual
hours required to correct and to process the data— per delivery unit.).
Invoicing and Payment Terms
Sanborn shall invoice monthly for percent complete. Payment terms for all valid
invoices received are NET30 from date of invoice.
Production Schedule
Sanborn will commence work upon receipt of the signed work other from CAPCO.
Final data will be completed and delivered on or before September 30, 2003. Delivery of
final data is dependent upon actual date of acquisition of photography. Adjustments to
the production schedule will be made for any events that delay production.
CAPCO Ortho Update: Fee Schedule - City of Round Rock 7
cwt... and Propk 02002 The Genbom MaP canVanY.Nq ALLPIGHTS f1ESERVEc
Capital Area Planning Council
FEMAtLIDAR81 ecifications
Guidelines and Specifications for Flood Hazard
Mapping Partners
Appendix A
Guidance for Aerial Mapping and Surveying
A.1 Introduction
This Appendix presents Federal Emergency Management Agency (FEMA) aerial mapping and
surveying guidelines and specifications that have been established to specify the quality of the
spatial data products to be produced, including work maps and base maps used in the
production of Flood Insurance Rate Maps (FIRMs), Digital Flood Insurance Rate Maps
(DFIRMs), and DFIRM - Digital Line Graphs (DFIRM - DLGs). The term "FIRM" is used
generically hereinafter to specify this "family" of FEMA spatial products.
This Appendix also includes guidance for ground surveys of control points, cross sections, and
hydraulic structures; topographic mapping using photogrammetry, LIght Detection and
Ranging (LIDAR) or other airborne remote - sensing technologies, consistent with FEMA and
industry standards.
[Febnrary2002]
A.8 Airborne Light Detection and Ranging (LIDAR) Surveys
When Mapping Partners choose to use airborne LIDAR systems for gathering the data
necessary to create digital elevation data for hydraulic modeling of floodplains, digital terrain
maps, and other NFIP products, the guidelines and specifications presented in this section of
these Guidelines must be used.
CAPCO Ortho Update: Fee Schedule - City of Round Rock
ConMendal and Pmpleasry.O 2002Te G.womaW Ganyen,.IDC.NLRIGHTS RESERVED
8
Capital Area Planning Council
LIDAR systems may not be able to gather all of the data necessary to create those products.
Data in areas such as bodies of water or dense forests may not meet the requirements of this
Appendix. For FEMA products containing such areas, the assigned Mapping Partner shall
supplement LIDAR data with data acquired by other means, as needed for hydraulic modeling.
Lesser standards may be applied for hydrologic modeling of watersheds or other studies.
The guidelines and specifications herein are to be used by FEMA Mapping Partners who use
LIDAR systems for data gathering purposes.
[February 2002]
A.8.1 System Definitions
For the purpose of these Guidelines, LIDAR is defined as an airborne laser system, flown
aboard rotary or fixed -wing aircraft, that is used to acquire x, y, and z coordinates of terrain and
terrain features that are both manmade and naturally occurring. LIDAR systems consist of an
airbome GPS with attendant GPS base stations, Inertial Measurement Unit (IMU), and light -
emitting scanning laser.
The system measures ranges from the scanning laser to terrain surfaces within a scan width
beneath the aircraft. The time it takes for the emitted light (LIDAR return) to reach the earth's
surface and reflect back to the onboard LIDAR detector is measured to determine the range to
the ground. Scan widths will vary, depending on mission purpose, weather conditions, desired
point density and spacing, and other factors.
The other two components of LIDAR systems are the airbome GPS, which ascertains the in-
flight three - dimensional position of the sensor, and the IMU, which delivers precise
information about the attitude of the sensor, i.e., the roll, pitch and heading.
[February 2002]
A.8.2 General Guidelines for Use
Two important factors in the LIDAR system mission planning are the point density of the
randomly spaced LIDAR points and the point spacing of the uniformly spaced DEM points
derived from the randomly spaced LIDAR returns. The correct point density necessary to
accurately represent terrain and terrain features will depend on flight conditions, mission
purpose, and required accuracy. As discussed in Sections A.3 and A.4, DEM point spacing of
5 meters or less and vertical accuracy of 1.2 feet at the 95- percecent confidence level
(Accuracy) is required for digital elevation data equivalent to 2 -foot contours for flat terrain,
and Accuracy of 2.4 feet is required for digital elevation data equivalent to 4' -foot contours for
rolling to hilly terrain.
Flight -path planning is another important factor in the LIDAR system mission. The flight path
shall cover the study area satisfactorily including both parallel and enough cross flight lines to
eliminate shadowing and allow for proper quality control.
CAPCO Ortho Update: Fee Schedule - City of Round Rock
Confidential and P pklan, 0 2002 The Santoro wp Company. Inc. ALL RIGHTS RESERVED
9
Capital Area Planning Council
Unlike aerial photogrammetry, LIDAR missions can be flown without regard to sun angle.
Flights may take place at night, if conditions otherwise allow. However, it is recommended that
some form of imagery exist over the LIDAR area. Simultaneous video or digital imagery
cannot be acquired if LIDAR data are acquired at night, but LIDAR intensity returns can be
acquired day or night, and these help to identify features during LIDAR post processing.
Alternatively, digital orthophotos acquired at a different time can be used for this purpose.
Elevation and measurement information related to subsurface channel and hydraulic structure
geometry shall be obtained through the use of other mapping technologies over deep or turbid
water. In some instances, shallow water and near -shore coastal surveys can be accomplished
using airbome LIDAR bathymetric systems equipped with lasers operating in portions of the
light spectrum that allow transmission through water.
LIDAR system tolerance for inclement weather conditions (e.g., high winds, wet snow, rain,
fog, high humidity, low cloud cover) generally is higher than that of photogrammetric methods.
However, such conditions have been known to degrade the accuracy of laser return data.
Therefore, Mapping Partners shall generally avoid missions during inclement weather.
High point densities may allow satisfactory data collection in areas of dense foliage. Still, care
shall be taken in planning missions with regard to both natural (vegetative) and manmade
(structure) ground cover. Pulse width, beam divergence, first and last pulse return
discrimination, and choice of the post - processing algorithms used for vegetation or structure
removal may all affect the accuracy of LIDAR - derived data in areas of dense foliage.
[February 2002]
A.8.3 Performance Standards
The accuracy standards in Sections A.3 and A.4 of this Appendix also shall apply to NFIP
maps and map products derived from LIDAR systems. LIDAR - derived data shall have the
accuracy required to produce topographic maps and products that meet NS SDA.
FEMA is not aware of any existing LIDAR system performance standards. Current information
about LIDAR systems is available from ASPRS (See ASPRS, 2001), National Oceanic and
Atmospheric Administration (NOAA), National Aeronautic and Space Administration, U.S.
Army Corps of Engineers, LIDAR system manufacturers and venders, and private firms that
provide LIDAR system services. As professional or trade associations issue specifications and
standards, FEMA may adopt those standards and specifications and amend this Appendix.
[February 2002]
A.8.3.1 Overall Standards
The assigned Mapping Partner shall furnish all necessary materials and equipment. The
assigned Mapping Partner also shall supply the supervisory, professional, and technical
services personnel required to manage, survey, document, and process all data associated with
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LIDAR system mapping, scanning, and digital image processing. The assigned Mapping
Partner shall provide all deliverables in accordance with the contract or other agreement with
FEMA and the requirements in this Appendix.
DEM posting shall be the minimum allowed by the data and shall not exceed 5 meters. As
specified in Section A.3, Accuracy, shall normally be 1.2 foot (equivalent to 2 -foot contours)
in flat terrain and 2.4 feet (equivalent to 4 -foot contours) in rolling to hilly terrain.
[February 2002]
A.8.3.1.1 Data Voids
For the purposes of this Appendix, areas not within two times the DEM posting of data points
are data voids. Data voids may occur from several different causes, including the following:
• LIDAR pulses may be naturally absorbed by water bodies or areas recently covered with
asphalt. Such voids are normally considered to be unavoidable.
• The LIDAR system may have malfunctioned for some reason.
• Heavy winds, flight navigation system (FMS) error or pilot error may have caused
"holidays" between flight lines.
• Data points may be intentionally removed as part of the bare -earth post- processing to delete
points that impinged on the tops of manmade structures or failed to penetrate dense
vegetation.
Data voids caused by system malfunctions or flight line holidays are unacceptable, requiring
new flights. Data voids caused by removal of LIDAR data points on manmade structures are
always acceptable. Data voids caused by removal of LIDAR data points on dense vegetation
are subject to additional guidelines, depending on whether or not the voids exist inside or
outside the floodplain for which hydraulic modeling is to be performed:
When data voids exist outside the floodplain, hydrologic modeling of the watershed can still be
performed acceptably by "filling" the voids through interpolation from surrounding points.
When data voids exist inside the floodplain, the cause of the data voids, the size of the voids,
and the location of the voids all have a bearing on whether additional ground surveys will be
required to "fill" the voids. For example, if the data voids are caused by dense mangrove or
sawgrass areas, supplemental ground surveys within such areas are not needed. These voids are
normally "filled" by interpolation from elevation points immediately surrounding the mangrove
or sawgrass areas. When small data voids of less than 1 acre are caused by removal of points in
other types of dense vegetation, similar interpolation procedures may be employed at the
discretion of the FEMA Lead.
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The principal scenario where additional ground surveys are required involves larger void areas,
normally larger than 1 acre, located in areas where representative cross sections must be cut. If
equally acceptable areas exist elsewhere to cut representative cross sections, the FEMA Lead
may decide that the additional expense is unwarranted for filling larger data voids by ground
surveys. This "judgment call" is roughly equivalent to photogrammetric mapping where the
photogrammetrist cannot see through the dense vegetation, determines areas to be "obscured,"
and maps the contours with dashed lines. In such cases, the photogrammetrist compiles
representative cross sections only where the bare earth terrain can be seen in stereo, and
performs ground surveys of additional cross sections only if alternative photogrammetrically
compiled locations for cross sections are determined to be unacceptable.
[February 2002]
A.8.3.1.2 Artifacts
Artifacts are regions of anomalous elevations or
oscillations and ripples within the DEM. data
resulting from systematic errors, environmental
conditions, or incomplete post - processing. They
may result from malfunctioning sensors, poorly
calibrated instrumentation, adverse atmospheric
conditions, or processing errors. When artifacts
are not totally removed, the assigned Mapping
Partner shall provide an analysis of the effects of
the remaining artifacts on DEM accuracy. The
analysis shall include a description of the causes
(contributing sources) of the artifacts and a
description of the steps taken to eliminate them.
Again, imagery is helpful in identification of
artifacts. Figure A-4 shows examples of artifacts
that remain after automated post- processing and
prior to manual post - processing of LIDAR data. Since a major portion of post - processing costs
pertain to manual post- processing which could consume as much as 80 percent of the total
budget for a LIDAR project, the FEMA Lead may decide that it is not cost effective to require
the bare -earth digital terrain data to be 100 percent clean and free of artifacts. As with data
voids, the severity of such artifacts depends upon their size and location. In fact, the removal
of such artifacts would create new data voids; therefore the guidelines are essentially identical.
Artifacts outside the floodplain, but inside the watershed, have no bearing on hydraulic
modeling and can be neglected. Often, LIDAR cross sections can be "cut" in areas other than
where the artifacts remain; and additional ground surveys are required only if necessary to
"cut" cross sections through such artifact areas.
Figure A-4 Example of Artifacts
The exception to this policy is in the event that the Mapping Partner needs DEMs to be 100
percent clean of artifacts for reasons other than hydraulic modeling (e.g., for community GIS
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requirements). In such cases, other criteria must be applied to justify the additional costs for
removal of all artifacts.
[February 2002]
A.8.3.1.3 Outliers
During the RMSE calculation process in which survey checkpoints are compared to the
interpolated TIN values, for example, discrepancies may exist between the two values. Some of
the discrepancies may be larger than expected, especially in steep terrain or if a "blanket" of
dense vegetation such as mangrove, sawgrass, or dense wheat fields exists where the LIDAR
may accurately survey the top surfaces of such vegetation rather than penetrating to the ground;
in areas of complex topography (e.g., levees that look like hedge rows, boulders that look like
haystacks); or in forested areas where removal of the top canopy may yield a lower canopy of
underbrush that still does not represent the bare -earth terrain. If there are a limited amount of
larger than normal differences between the LIDAR interpolated elevations and the elevations
of surveyed checkpoints, this may have a significant impact on the final RMSE calculation.
Outliers often occur as a result of the failure to achieve a true bare -earth surface from the
vegetation removal process. A single outlier can override dozens or hundreds of accurate
checkpoints, making the entire RMSE value appear to be poor. When this occurs, the
coefficient of skew may indicate that the errors do not have a normal distribution, a sign that
the RMSE calculation may be misleading. (See Subsection A.8.6.3.4.) Having a Large quantity
of outliers may highlight improper post processing. In order to deal with outliers, a criterion
may be established to remove a small percentage of the total number of checkpoints surveyed
which exhibit the largest discrepancies. Statisticians almost unanimously agree that errors
exceeding the "3- sigma" level are outliers; the "3- sigma" level provides confidence at the
99.75% confidence level, enabling only the worst 0.25% of a dataset to be discarded as
outliers. Less stringent criteria consider the discarding of the worst 1%, 5% or 10% of the data.
Allowing 10% outliers would be in accord with the traditional National Map Accuracy
Standard where the worst 10% of all checkpoints are treated as outliers that can be discarded,
regardless of size. The PO is free to consider the provision of a limited percentage of outliers,
especially if the skew calculation indicates that the dataset lacks a normal distribution. The
option to collect additional check points to replace the outliers may be considered.
[February 2002]
A.8.3.2 System Calibration
LIDAR system components are most effectively tested and calibrated by the equipment
manufacturer. Therefore, the Mapping Partner shall provide FEMA with evidence of
manufacturer calibration.
In addition to evidence of manufacturer calibration of system components, the Mapping
Partner shall submit evidence that the total LIDAR system was calibrated prior to project
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initiation for the purposes of identifying and correcting systematic errors. Proper system
calibration requires repetitive overflight of terrain features of known and documented size and
elevation using flight paths similar to those that will be used in the study area. For some
projects, daily in -situ calibrations may be required.
[February 2002]
-sy÷
A.8.3.3 Flight Planning
Planning a flight path that considers all aspects of data collection is critical to the success of the
mission. An analysis of the project area, project requirements, topography, proximity to
restricted air space, and other factors will determine the flight path configuration. The mission
should include parallel flight lines and, for quality control purposes, at least one cross flight
line. The spacing between the flight lines will depend on the desired amount of sidelap
between swaths and the terrain.
The density and accuracy of data generated by different equipment vary widely. The assigned
Mapping Partner shall have the flexibility of providing a flight path to create the necessary
point density to meet the posting and accuracy requirements and minimize the occurrence of
data voids.
The assigned Mapping Partner shall check the Position Dilution of Precision (PDOP) in the
study area. The PDOP is an indicator of the positional accuracy that can be derived from the
current GPS satellite geometry, which varies continuously; the smaller the PDOP number, the
higher the data quality.
The assigned Mapping Partner shall document mission date, time, flight altitude, airspeed, scan
angle, scan rate, laser pulse rates, and other information deemed pertinent. For a sample
mission data recordation checklist, refer to Table A-4, which appears at the end of this
Appendix.
[February 2002]
A.8.3.4 Global Positioning System (GPS) Base Stations
The assigned Mapping Partner shall select the GPS base stations carefully to ensure reliable
differential processing of airbome GPS data. NGS recommends the simultaneous use of two
GPS base stations during the mission. Either public- or private- domain GPS base stations are
suitable for use for this purpose, provided they are within the acceptable GPS baseline Limits.
Normally 20 kilometer baseline lengths are maximum for high- accuracy LIDAR surveys,
where the airborne GPS error component should contribute no more than 5 centimeters to the
vertical error budget.
Where possible, GPS base stations shall have ellipsoid heights to an accuracy of 2 centimeters
relative to the Continuously Operating Reference Stations or the High Accuracy Reference
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Network. The assigned Mapping Partner shall use high- quality, dual- frequency GPS receivers
and associated antennae at the GPS base stations.
[February 2002]
A.8.4 Accuracy Reporting Methodology
FGDC documented a common methodology for determining and reporting the accuracy of
horizontal and vertical coordinates for geodetic control points (survey monuments) in FGDC-
STD -007.1 and FGDC -STD- 007.2. Additional guidance is included in NGS -58 (NOAA,
1997).
[February 2002]
A.8.5 Post - Processing of Data
For hydraulic modeling, the assigned Mapping Partner shall provide high - resolution, high -
accuracy, "bare- earth" ground elevation data. To restrict data to ground elevations only, the
Mapping Partner shall remove elevation points on bridges, buildings and other structures, and
on vegetation from the LIDAR- derived data. In addition to randomly spaced LIDAR points,
before and after removal of data associated with structures and vegetation, the assigned
Mapping Partner shall produce a bare -earth TIN as well as a DEM, with the minimum regular
point spacing, no greater than 5 meters, allowed by the data in eastings and northings. The
assigned Mapping Partner shall use TIN linear interpolation procedures when validating the
vertical accuracy of the elevation dataset. Accuracy assessments should normally be performed
on the TIN and not on the DEM which is a derived product of slightly lower accuracy.
Using digital orthophotos, stereo photogrammetry, or other source materials, the assigned
Mapping Partner shall produce breaklines for stream centerlines, drainage ditches, tops and
bottoms of streambanks, ridge lines, road crowns, levees, bulkheads, seawalls, road/highway
embankments, and selected manmade features that constrict or control the flow of water (e.g.,
curb lines). When merged with mass points, brealdines are used to enforce TIN triangle edges.
The assigned Mapping Partner also shall specify the sources and accuracy of breakline data.
Brealdines are not depicted for small culverts that pass under roads unless those culverts (or
ditches leading in and out of them) are visible on available imagery without the use of
photogrammetric stereo compilation which is normally too expensive for this purpose.
[February 2002]
A.8.6 Quality Assurance /Quality Control
QA/QC of the LIDAR - derived data is primarily the responsibility of the assigned Mapping
Partner. This QA/QC process shall include reviews of flight alignments and completeness of
supporting data (e.g., cross sections, profiles). Until LIDAR technology and procedures
become mature, FEMA will normally provide funding for independent QA/QC testing.
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[February 2002]
A.8.6.1 Vertical RMSE Standards
When systematic errors have been corrected and remaining errors have a normal distribution,
the NSSDA uses the root mean square error (RMSE) to estimate both horizontal and vertical
accuracy. RMSE is the square root of the average of the set of squared differences between
dataset coordinate values and coordinate values from an independent source of higher accuracy
for identical points. If those differences are normally distributed and average zero, 95 percent
of any sufficiently large sample should be less than 1.96 times the RMSE. Therefore, vertical
RMSE of 18.5- centimeters is often referred to as equivalent to 2' contours, or "37- centimeter
accuracy at the 95- percent confidence level." Following that convention, the vertical accuracy
of any digital elevation dataset is defined as 1.96 times the RMSE of' linearly interpolated
elevations in that dataset, as compared with known elevations from high- accuracy test points.
For the NFIP, TINS (and DEMs derived therefrom) should normally have a maximum RMSE
of 18.5 cm, equivalent to 2' contours, in flat terrain; and a maximum RMSE of 37 cm,
equivalent to 4' contours, in rolling to hilly terrain. The Mapping Partner shall field verify the
vertical accuracy of this TIN to ensure that the 18.5 cm or 37.0 cm RMSE requirement is
satisfied for all major vegetation categories that predominate within the floodplain being
studied.
[February 2002]
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A.8.6.2 Ground Cover Categories
The assigned Mapping Partner shall separately evaluate and report on the TIN accuracy for the
main categories of ground cover in the study area, including the following:
1. Bare -earth and low grass (plowed fields, lawns, and golf courses);
2. High grass, weeds, and crops (hay fields, corn fields, and wheat fields);
3. Brush lands and low trees (chaparrals, mesquite);
4. Forested, fully covered by trees (hardwoods, evergreens, and mixed forests);
5. Urban areas (high, dense manmade structures);
6. Sawgrass; and
7. Mangrove.
Ground cover Categories 1 through 5 above are fairly common everywhere. FEMA experience
with Categories 6 and 7 is that sawgrass and mangrove each have vegetation so dense that
LIDAR pulses do not penetrate to the ground, but instead map the top reflective surface. The
assigned Mapping Partner must treat such areas like "obscured terrain" with conventional
photogrartunetry whereby bare earth elevations within such vegetation category polygons can
only be estimated by interpolating elevations from ground points surrounding such polygons.
The assigned Mapping Partner may further subdivide and expand the above definitions to
better accommodate the predominant vegetation types in the study area. The assigned
16
Capital Area Planning Council
Mapping Partner shall distribute sample points throughout each category area being evaluated
and not group the sample points of the same type in a small sub -area.
The assigned Mapping Partner shall select a minimum of 20 test points for each major
vegetation category identified. Therefore, a minimum of 60 test points shall be selected for
three (minimum) major land cover categories, 80 test points for four major categories, and so
on. The Mapping Partner shall consider establishing test points when planning field surveys to
gather cross section data for hydraulic modeling. Confidence in the calculated RMSE value
increases with the number of test points and is a function of sample size. By specifying a
minimum of 60 checkpoints (20 each in three or more land cover categories), FEMA is
specifying that 60 test points are the minimum necessary for a practical level of confidence in
the calculated RMSE statistic but recognizing that a higher number of checkpoints will provide
higher confidence that performance standards have been achieved.
The test points are to be selected in terrain that is flat or uniformly sloped within 5 meters in all
directions. The uniform slope must not exceed 20 percent. The test points must never be
located near to brealdines, such as bridges or embankments. Test points on sloping or irregular
terrain would be unreasonably affected by the linear interpolation of test points from
surrounding TIN points and, therefore, shall not be selected.
[February 2002]
A.8.6.3 Analysis of Error Frequency Distribution
The RMSE process assumes that errors have a normal distribution (bell curve) with zero mean,
and that all systematic errors have been removed. This is rarely the case, especially with
LIDAR data. Some systematic errors or biases remain undetected, even after regular
calibrations of LIDAR systems. This Subsection addresses statistical processes for evaluating
whether the errors have a central tendendy close to zero, evaluating the measure of general
variability, and evaluating the measure of skewness. Unfortunately, no hard and fast rules to
pinpoint problems exist, but each of the statistical processes mentioned have some value in
detecting the potential presence of systematic errors, for which further investigations are
warranted, especially if the RMSE calculation fails to pass the vertical accuracy criteria
established for the project.
[February 2002]
A.8.6.3.1 Histograms
The most common form of error analysis is to develop a histogram of all errors. If a dataset
tabulates errors for all checkpoints, a histogram might show how many of those errors fell
within different 5- centimeter ranges, for example, graphing the number of errors between the
following error values: - 50 cm, -45 cm, -40 cm, -35 cm, -30 cm, -25 cm, -20 cm, -15 cm, -10
cm, -5 cm, 0, +5 cm, +10 cm, +15 cm, +20 cm, +25 cm, +30 cm, +35 cm, +40 cm, +45 cm,
and +50 cm. Histograms illustrate whether the errors are unimodal, bimodal, or multimodal,
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-30 -25 -20 -15 -10 -05 0 +5 +10 +15 +20 +25
+30
have small or large variability, or are skewed on either the positive or negative side. Often,
such histograms for LIDAR data appear to approximate a normal distribution, except that it
does not have a zero mean; this would appear to indicate the presence of uncorrected
systematic error. Separate histograms for individual land cover categories often depict
significantly different characteristics that help to understand LIDAR system performance
(including post - processing) in the different categories. Figure A -5 is an example of a histogram
reflecting checkpoint errors from a LIDAR dataset that does approximate a normal error
distribution.
[February 2002]
Figure A -5 Histogram for Checkpoint Errors in LIDAR Dataset
A.8.6.3.2 Measures of Central Tendency
Three common measures of the central tendency of errors in a dataset may be used to quantify
the nearness to or departure from the expected central tendency of zero:
• The Arithmetic Mean is the sum of all the errors, divided by the number (n) of checkpoints.
When the mean error is large, this is an indicator that systematic errors may be present.
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• The Median is the value at which there are as many larger errors as there are smaller errors.
• The Mode is the value at which the greatest number of errors is concentrated. In a
histogram, the mode is the error value or error range which has the highest ordinate value at
the peak of the histogram.
[February 2002]
A.8.6.3.3 General Variability
Various measures of general variability for statistical data exist, including range, average deviation,
RMSE, standard deviation, and variance. However, the industry standard for geospatial data is the
RMSE explained in Sections A.2 and A.3. For the dataset used to compute the histogram in Figure A -5,
the RMSE = 11.7-centimeters which equates to vertical Accuracy: of approximately 22.9- centimeters at
the 95- percent confidence level. The standard deviation (a or sigma) is primarily used for determination
of statistical outliers, i.e., elevation errors that exceed the 3 -sigma level.
[February 2002]
A.8.6.3.4 Skewness
Skewness is the condition of being asymmetrical or lopsided, and departing from the expected
normal distribution shown by the "bell curve." The coefficient of skewness (a unitless number)
is used to compute the asymmetry of the errors about the arithmetic mean error. When the
absolute value of the skew exceeds 0.5, this means that the error distribution is asymmetrical
and may not represent a normal distribution. The Mapping Partners should investigate all
datasets with skew values exceeding ±0.5 to determine if there is a valid reason why the errors
do not have a normal distribution (a basic assumption in calculation of RMSE values). For the
dataset used to compute the histogram in Figure A -5, the skew is 0.429. The skew is computed
automatically by Microsoft Excel and other spreadsheets, and uses calculations of the second
and third central moments of the dataset.
The coefficient of skew is zero when the error distribution is perfectly symmetrical.
[February 2002]
A.8.6.4 Error Assessment
When a LIDAR dataset does not pass the vertical accuracy standard, steps must be taken to
identify the cause of the errors. Systematic corrections should never be applied without first
identifying the cause of errors. Many factors could have contributed to errors, including the
following:
• The LIDAR aircraft may have flown at too high of an altitude, causing IMU angular errors
to propagate to larger errors on the ground from a higher altitude.
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• The GPS baselines may be too long, flying too far from the GPS base stations, and causing
larger than normal errors in airborne GPS positions.
• The scan angle may have been too large or the airspeed too fast, causing wider point
spacings and fewer laser pulses that were near vertical.
• The satellite PDOP may have been too high, reducing the accuracy of airborne GPS
positions.
• The post - processing algorithms may have been applied incorrectly.
There may have been systematic errors with the airborne GPS, IMU, or laser scanner.
The list of potential causes is a long one because the process is complex.
Many of the statistical tools described in Subsection A.8.6.3 may point to the apparent
existence of systematic errors. The following are standard procedures to be used by FEMA's
Mapping Partners to "trouble shoot" total LIDAR systems in order to isolate systematic errors:
[February 2002]
A.8.6.4.1 Assessments by Land Cover
If ground cover category 1 (bare earth, sand, rock, dirt, short grass) does not pass the vertical
accuracy standard, the potential causes are different from potential causes when vegetated or
urban areas do not pass. Ground cover category 1 essentially should always pass accuracy
standards, unless something systematic is wrong. Daily calibration tests help to confirm that
the system performed well at the calibration test site (on that same day with the same sensor),
and the calibration site normally includes bare earth terrain and short grasses. If ground cover
categories 3 or 4 (see Subsection A.8.6.2) alone do not pass the vertical accuracy standard, the
most probable causes are shortcomings in the vegetation - removal procedures used in post -
processing. If ground cover category 5 (urban terrain) does not pass, something systemic about
urban buildings may cause the errors.
[February 2002]
A.8.6.4.2 Assessments by Error Locations
The Mapping Partner shall assess errors relative to their location within flight lines, or near the
beginning or end of swaths. This may indicate IMU errors or high satellite residuals due to
aircraft banking causing cycle slips and multipath.
[February 2002]
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A.8.6.4.3 Assessments by DateslSensors
When LIDAR datasets are flown on different dates, or with different sensors, the Mapping
Partner must consider these variables in the error analyses.
[Febntary 2002]
A.8.6.4.4 Airborne GPS Verification
The Mapping Partner shall examine GPS flight trajectories, compare the forward and reverse
flight trajectories' combined separation, check satellite health, check geo- magnetic
observations, and verify the following:
PDOP;
• GPS satellite residuals;
• Satellite phase RMS;
• Weighting adjustments when two or more differential base stations are used;
• Base station distance separation;
• Position standard deviations;
• Vertical datum used; and
• Correct application of Geoid99 calculation of orthometric heights.
[February 2002]
A.8.6.4.5 Inertial Measurement Unit (IMU) Verification
The Mapping Partner normally shall do the following to verify the accuracy of the IMU:
• Review the Kalman filter, the measurement residual ratio (MRR), and the consecutive
measurement rejections settings;
• Confirm IMU was in "fine align" mode for the whole of the dataset;
• Check accelerometer drift and scale factor, and the gyro drift and scale factor to ensure they
are within specifications;
• Compare GPS trajectory with recomputed IMU trajectory and investigate large
discrepancies; and
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• Review IMU to lever arm parameter measurements and ensure they are entered correctly in
the proper reference system.
[February 2002]
A.8.6.4.6 Laser Range Verification
The Mapping Partner shall normally do the following to verify the accuracy of the laser ranges:
• Review raw laser ranges;
Identify areas of high dropouts (no returns) and correlate them to justifiable features;
• Review scanner mirror angles (galvanometers or micro - controller);
• Examine intensity images if collected; and
Review system generated error log sheets.
[February 2002]
A.8.6.4.7 Total System Verification
To verify the accuracy of the whole system, the Mapping Partner shall do the following:
• Review calibration flights and compare to system flight parameters;
• Use CAD software to analyze individual flightlines and verify pitch, roll and heading
errors;
• Check overlap for roll and scaling errors;
Check ground features for pitch (i.e. buildings, bridges, etc.);
• Check scaling errors if water bodies exist;
• Compare cross flight data for attitude; and
• Verify vegetation removal procedure and review parameters if data were "corrected" or
adjusted for pitch, roll and heading errors; for example, was the iteration angle too high for
the terrain type? Is the morphological window within a reasonable size for area features
(e.g., is it too large and removes key components such as large dunes ?).
[February 2002]
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A.8.6.4.8 Systematic Error Corrections
It is relatively easy to determine the magnitude of systematic errors and adjust all data
accordingly, however, the assigned Mapping Partner must not be "correct" such errors until the
error source is clearly identified and documented. The Mapping Partner must report systematic
errors to the FEMA Lead for review before systematic reprocessing of data that initially failed
to pass the accuracy criteria.
[February 2002]
A.8.6.5 Cross Flight Verification
To supplement the QA/QC process for LIDAR data, the Mapping Partner may employ
different optional techniques to check not only the accuracy but also the precision. The balance
is to address the need for additional verification checkpoints with cost- effective methods that
aid in identifying the internal consistency (precision) of LIDAR data. Two GPS techniques that
may be utilized are continuous kinematic and Real Time Kinematic (RTK). Continuous
kinematic collects positional data every epoch while maintaining fixed ambiguities on a
minimum of five satellites. In the event of loss of lock on satellites, the integer ambiguities
must be recomputed to their fixed integer value before a sub decimeter position can be
calculated. Post processing is required to obtain the positional data. RTK is similar to
continuous kinematic except that the data do not need to be post - processed. The estimated
ambiguities are fixed to their integer values and positional data are calculated and stored in real
time. Both methods are efficient for GPS surveys along highways.
With both types of GPS procedures the process is to survey checkpoints perpendicular to the
LIDAR flight paths at different strategic locations, with these additional checkpoints along
roads or highways that transect the survey area. The assigned Mapping Partner shall conduct
surveys close to the center of roads and highways, but avoiding bridges, elevated roads, or
roads with steep embankments so that LIDAR points can be interpolated accurately without
concem for steep slopes. If the flights are flown north to south, then the checkpoints must
traverse east and west across the project area. A minimum of three cross lines must be
measured, one at each end of the flight lines and another through the center. Typically the
weakest data will be at the beginning of the flight line if the GPS and IMU have not stabilized
due to the turning of the aircraft. The center cross line will help identify if the airborne data are
stabilized. Ideally checkpoints should have a minimum point spacing of one half the LIDAR
swath width to ensure each swath has at least one checkpoint. Increasing the number of cross
flight checkpoints will assist in verifying confidence within the data. Because such surveys are
less accurate than the surveys of checkpoints to NGS -58 5- centimeter standards, these
additional verification points are not to be mixed with the survey checkpoints used to compute
the vertical RMSE or Accuracy,. However, this is a relatively inexpensive way to generate a
relatively large number of somewhat less - accurate checkpoints when there is concern that the
60, 80 or 100 checkpoints (20 each in the major land cover categories) are insufficient for
providing a high degree of confidence in the accuracy statistics.
[February 2002]
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A.8.7 Deliverables
All data and products associated with contract deliverables shall meet or exceed relevant
NSSDA standards and fully comply with the FGDC metadata format standard with the
provisions in the contract. The Mapping Partner shall use Appendix I of these Guidelines as a
guide for preparing and submitting deliverable products to FEMA in digital format.
[February 2002]
A.8.7.1 Pre - Project Deliverables
Prior to data collection, the Mapping Partner shall submit the following to the FEMA Lead or a
Mapping Partner designated by the FEMA Lead:
A map showing the study area boundaries and flight path, at a medium scale (1:24,000) or
small scale (1:50,000); typically, USGS maps are desirable for this purpose
• . Documentation specifying altitude, airspeed, scan angle, scan rate, LIDAR pulse rates, and
other flight and equipment information deemed appropriate; and
• A chart of areas of high PDOP, or a list showing the time of the beginning and end of high
PDOP.
[February 2002]
A.8.7.2 Post - Project Deliverables
Following project completion, the Mapping Partner shall submit the following to the FEMA
Lead or a Mapping Partner designated by the FEMA Lead:
A LIDAR system data report;
• A flight report;
• A ground control report;
• Data processing procedures for selection of postings, and all orthometric values of x, y, and
z coordinates for LIDAR returns. Elevations shall be orthometric heights; and
A system calibration report.
The LIDAR system data report shall include discussions of the following:
• Data processing methods used, including the treatment of artifacts;
• Final LIDAR pulse and scan rates;
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Capital Area Planning Council
• Scan angle;
• Capability for multiple returns from single pulses;
• Accuracy and precision of the LIDAR data acquired;
Accuracy of the topographic surface products;
• Any other data deemed appropriate;
• Companion imagery, if any; and
A digital spatial index showing the orientation of all data tiles within the project site with
tile labels corresponding to the CD (or other media) ID and file name on that CD.
The flight report shall document mission date, time, flight altitude, airspeed, and other
information deemed pertinent. The report shall include information about GPS- derived flight
tracks, provide a detailed description of final flight line parameters and GPS controls (i.e.,
benchmarks), and include ground truth and complementary reference data.
The ground control report shall include, at a minimum, all pertinent base station information
and mission notes, including information on GPS station monument names and stability.
[February 2002]
A.8.7.3 Delivery of Digital Data
In addition to the pre- and post- project deliverables described above, the Mapping Partner shall
submit the following:
• All raw datasets, dataset of survey points filling voids, dataset of transects (if generated),
bare -earth DEM data, and brealdines in separate data files; and
• Uniformly spaced DEM(s), on ISO 9660 standard CD -ROM (or DVD) media in a format
specified in Appendix L.
The Mapping Partner shall deliver raw datasets and LIDAR system data, including orthometric
heights for each point, in comma - delimited ASCII files in x, y, and z format. The Mapping
Partner shall deliver the DEM in the format designated on the Table A-4 checklist. The
Mapping Partner also shall flag raw datasets from sidelap and overlap areas of separate flight
lines. Breaklines shall be produced, and breakline files shall contain a flag record that
identifies them as breakline features and identifies their source and accuracy. The Mapping
Partner shall submit raw datasets in tiles or data models matching those of the DEM.
The Mapping Partner shall ensure that all deliverables conform to the projection, datum, and
coordinate system specified in the agreement with FEMA. File sizes cannot exceed 1 gigabyte,
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Capital Area Planning Council
unless otherwise specified by the FEMA Lead. Each file shall be organized to facilitate data
manipulation and processing.
[February 2002]
A.8.8 Acceptance /Rejection
The terms of acceptance /rejection in Section A.7.5.5 of this Appendix shall apply.
*Denotes Minimum Required Information
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•
DATE: February 7, 2003
SUBJECT: City Council Meeting — February 13, 2003
ITEM: 13.B.1. Consider a resolution authorizing the Mayor to execute an Interlocal
Contract for Orthophotography with the Capital Area Planning
Council for aerial photography updates of selected high growth
areas in and around the City.
Resource: Joe Vining, Planning Director
History:
In 2001 the City and CAPCO entered into an inter -local agreement to fly
the entire ETJ. The contract was completed in September 2001. Since
that time, rapid growth has taken place through out the ETJ and
surrounding areas. The SH45/La Frontera area was updated in early 2002
but continues to grow as more development has taken place. Several
other areas around the city have also experienced significant development
since 2001 as well. There is also a need for precise photography in the
area of the proposed SH130 /Chandler Rd. intersection.
The opportunity now exists to update selected portions of the aerial
imagery and topographic mapping in the Round Rock area, as CAPCO is
once again photo mapping the 10 county CAPCO region.
These much needed updates will greatly enhance the mapping and GIS
products used to support Planning, Public Works, Police, Fire, Parks and
Recreation, as well other Departments in the city and the general public.
Funding:
Cost: $69,991.92
Source of Funds: 1998 General Obligation Bonds
Outside resources: Capital Area Planning Council
Impact: None.
Benefit: Planning, Fire, Public Works and other departments will benefit
with their mapping programs and current data with updated
information captured from the new photography.
Public Comment: None required.
Sponsor: Planning and Community Development Department