20130919 22085400 1.0 FGDC CSDGM Metadata FALSE ORTHOS2012_6IN 002 1002499.949331 1207499.949331 1650000.092347 1845000.092347 1 Projected GCS_North_American_1983_HARN Linear Unit: Foot_US (0.304801) NAD_1983_HARN_StatePlane_Illinois_East_FIPS_1201_Feet <ProjectedCoordinateSystem xsi:type='typens:ProjectedCoordinateSystem' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xmlns:xs='http://www.w3.org/2001/XMLSchema' xmlns:typens='http://www.esri.com/schemas/ArcGIS/10.5'><WKT>PROJCS[&quot;NAD_1983_HARN_StatePlane_Illinois_East_FIPS_1201_Feet&quot;,GEOGCS[&quot;GCS_North_American_1983_HARN&quot;,DATUM[&quot;D_North_American_1983_HARN&quot;,SPHEROID[&quot;GRS_1980&quot;,6378137.0,298.257222101]],PRIMEM[&quot;Greenwich&quot;,0.0],UNIT[&quot;Degree&quot;,0.0174532925199433]],PROJECTION[&quot;Transverse_Mercator&quot;],PARAMETER[&quot;False_Easting&quot;,984250.0],PARAMETER[&quot;False_Northing&quot;,0.0],PARAMETER[&quot;Central_Meridian&quot;,-88.33333333333333],PARAMETER[&quot;Scale_Factor&quot;,0.999975],PARAMETER[&quot;Latitude_Of_Origin&quot;,36.66666666666666],UNIT[&quot;Foot_US&quot;,0.3048006096012192],AUTHORITY[&quot;EPSG&quot;,3443]]</WKT><XOrigin>-17463800</XOrigin><YOrigin>-46132600</YOrigin><XYScale>137244822.07846552</XYScale><ZOrigin>-100000</ZOrigin><ZScale>10000</ZScale><MOrigin>-100000</MOrigin><MScale>10000</MScale><XYTolerance>0.0032808333333333331</XYTolerance><ZTolerance>0.00020000000000000001</ZTolerance><MTolerance>0.00020000000000000001</MTolerance><HighPrecision>true</HighPrecision><WKID>3443</WKID><LatestWKID>3443</LatestWKID></ProjectedCoordinateSystem> 20180503 14041200 20180503 14052100 625000 5000 ItemDescription Version 6.2 (Build 9200) ; Esri ArcGIS 10.5.1.7333 Cook County 2012 Aerial Imagery (Contract No. 10-41-09), 1:1,200-Scale (1" = 100') Tiled 4-band (R, G, B, NIR) Digital Orthoimagery for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Raster Digital Data, Version 1.0. Published April 2013. The digital orthoimagery for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, is stored as an image layer in SDE and is displayable in ArcInfo and ArcView. This image layer is a collection of georeferenced images mosaicked into a logically contiguous image and is in an RDBMS table. The metadata for this data set is one (1) of a series of nine (9) reports. In addition to this metadata report, metadata exists for: FLIGHT LINES Cook County 2009 Aerial Imagery Project (Contract No. 10-41-09), Flight Lines for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Geodatabase Vector Digital Data, Version 1.0. Published April 2013. PHOTO-IDENTIFIED CONTROL POINTS Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), Photo-identified Control Points for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Geodatabase Vector Digital Data, Version 1.0. Published April 2013. STEREO MODEL LIMITS Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), Stereo Model Limits for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Geodatabase Vector Digital Data, Version 1.0. Published April 2013. CENTERS OF DIGITAL PHOTOGRAPHS Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), Centers of Digital Photographs for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Geodatabase Vector Digital Data, Version 1.0. Published April 2013. UNPROCESSED DIGITAL IMAGES Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), 1:6,350-Scale Tiled 4-band (R, G, B, NIR) "Unprocessed" Digital Mapping Camera Images for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Raster Digital Data, Version 1.0. Published April 2013. "SPECIAL CONSIDERATION AREA" DEM Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), Digital Elevation Model "DEM" for Cook County's "Special Consideration Area," Illinois. Triangulated Irregular Network, Version 1.0, Published April 2013. TILE INDEX Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), Tile Index for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Geodatabase Vector Digital Data, Version 1.0. Published April 2013. NORTHEASTERN ILLINOIS DEM Cook County 2012 Aerial Imagery Project (Contract No. 10-41-09), Digital Elevation Model "DEM" for northeastern Illinois, Version 1.0, Published April 2013. 2009-03-09T00:00:00 2009-05-13T00:00:00 2012 20090513 Alan Hobscheid Cook County Bureau of Technology GIS Manager, Department of Geographic Information Systems 69 W. Washington Street, Room 2700 Chicago Illinois 60602 alan.hobscheid@cookcountyil.gov US 312-603-1399 312-603-9713 09:00 - 17:00, Central Time Zone, Monday - Friday, except holidays Please contact during normal business hours. 1 -88.267019 -87.515457 41.732167 41.194159 This data set was created to serve as part of a standard database for virtually all geospatial applications in Cook County, and is intended to support general location, planning, and cartography projects, as well as general inventory and asset management, Census analysis and mapping, and geocoding by address. The orthophotos were created as a control and foundation for planimetric and cadastral data sets and to provide a visual baseline for Cook County. <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>This digital geospatial file consists of a series of raster digital orthophoto images covering all of Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. The images have a pixel resolution of 0.5 feet which generated an orthophotographic database with a mapping scale of 1" = 100'. The imagery for the "Countywide Flight" was collected between March 9th, 2012 and May 11th, 2012. The imagery for the "Special Consideration Area" was collected on March 10th, 2012 and May 13th, 2012. (Refer to the relevant Process Step for a description of the principal differences between these two flights.) A digital orthoimage is a raster image of remotely sensed data that has had displacement in the image introduced by sensor orientation and terrain relief removed. Digital orthoimages combine the image characteristics of photography with the geometric qualities of maps. The normal orientation of this data is by lines (rows) and samples (columns). Each sample in this data set contains a series of pixels ordered from west to east with the order of the lines from north to south. The data set is tiled for dissemination into 18,905 separate tiles, each of which is 2500 feet on a side. This digital geospatial file has been orthorectified using survey control points obtained through both Airborne Global Positioning Systems and Ground Control Survey. This dataset is projected using the Transverse Mercator map projection. The grid coordinate system used is the Illinois State Plane Coordinate System, East Zone (Zone Number Zone 3776, FIPS 1201), NAD 83 (NSRS2007) (horizontal datum), with ground coordinates expressed in U.S. Survey Feet. Each tile consists of two files, a TIFF (Tagged Image File Format) (.tif), and an ASCII geo-referencing header file (.tfw). Each tile is approximately 100MB in size resulting in a total of 1.9TB for the region.</SPAN></P></DIV></DIV></DIV> digital ortho-photograph digital ortho orthorectified image digital image digital ortho-photo rectified photograph rectified image orthophoto digital ortho-imagery ortho-image Color orthoimagery Color orthophotographs 4-band four-band Imagery base maps and land cover Illinois northeastern Illinois Chicago Cook County DuPage County Kane County Kendall County Lake County McHenry County Will County Grundy County digital ortho-photograph, digital ortho, orthorectified image, digital image, digital ortho-photo, rectified photograph, rectified image, orthophoto, digital ortho-imagery, ortho-image, Color orthoimagery, Color orthophotographs, 4-band, four-band, Imagery, base maps, and land cover Illinois, northeastern Illinois, Chicago, Cook County, DuPage County, Kane County, Kendall County, Lake County, McHenry County, Will County, Grundy County Cook County Board of Commissioners, Merrick & Company <DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>Access to this feature dataset is available to county and municipal agencies. Editing privileges are restricted to authorized GIS staff members or its designees.</SPAN></P></DIV></DIV></DIV> Under no circumstances may the data be redistributed or made available over a network without explicit permission from the Cook County Bureau of Technology. It is required that the Cook County Board of Commissioners be cited in any products generated from the data. The following source citation must be included: "Cook County 2012 Aerial Imagery (Contract No. 10-41-09), 1:1,200-Scale (1" = 100') Tiled 4-band (R, G, B, NIR) Digital Orthoimagery for Cook, DuPage, Grundy, Kane, Kendall, Lake, McHenry, and Will County, Illinois. Raster Digital Data, Version 1.0. Published April 2013." 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B9EE7B00-4466-4F2D-AD72-A22E99BD1A1E Mike Hoather Sub-contractor to Merrick & Company 225 West Huron Street, #516 Chicago Illinois 60654 mhoather@live.com US 773-251-4678 09:00 - 17:00, Central Time Zone, Monday-Friday, except holidays Please contact during normal business hours This metadata file is intended to accompany the geospatial data set identified and received from Cook County. It is not to be altered or summarized. Cook County does not support secondary distribution. If this geospatial data set was received from anyone besides the Cook County Bureau of Technology, this metadata file and the geospatial data set it describes may lack integrity.</ Mike Hoather Sub-contractor to Merrick & Company 225 West Huron Street, #516 Chicago Illinois 60654 mhoather@live.com US 773-251-4678 09:00 - 17:00, Central Time Zone, Monday-Friday, except holidays Please contact during normal business hours Mike Hoather MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated 1) Ground Control Data Collection for Aerotriangulation Adjustment Using a photo identification methodology, physically identifiable ground features (e.g., manholes, sidewalk intersections, etc.) are coordinated with x, y, and z values. This method achieved the same accuracies as acquisition of ground control via selection of new or existing monuments. Photo-id control points were selected in open and flat areas (e.g., roads, clearings, etc.) and were placed and spaced consistently throughout the project area. Photo-id control points were ground features. No above ground features were selected. Photo-id control points were physically tied to base stations used in support of the imagery acquisition. (For more information about the raw "unprocessed" digital imagery used to derive the ortho-imagery or the ground control points, please review specific metadata associated with these datasets.) ABGPS technology was used to supplement Control Points as input into the aerotriangulation adjustment. The ABGPS control system consisted of on-board single and dual-frequency receivers. The following data was collected with ABGPS: 1. Time tagged exposures to accommodate post processing with the ABGPS data resulting in X,Y,Z of photo centers. 2. X,Y,Z coordinates collected at 1 second intervals via the ABGPS unit for post processing. 3. X,Y,Z coordinates at the base station collected for post processing and differential correction. 4. Kappa, Phi, Omega from the inertial measurement units (IMUs) at each image exposure to record the position of the camera to account for the attitude of the aircraft. 5. Accelerometer data from the IMU that documents the aircraft's velocity. In-flight ABGPS and IMU data were recorded on a "ruggedized" laptop computer. Data files were delivered to the aerial flight manager to track aerial progress and provide post processing with the aerial image data. Each aircraft was equipped with a GPS antenna that had been integrated into the imaging system. Dual frequency, multi-channel receivers were placed onboard the aircraft to collect data for post processing with ground base station data. Base stations were used during flight operations to provide the differential signal required for accurate positioning calculations of the aircraft's antenna during aerial image capture. The receivers recorded the GPS (dual frequency - L1/L2) satellite signals of all satellites available in view, to ensure project accuracy standards were met. In-flight navigation along flight lines was provided using the GPS navigation module. An on-board GPS unit received satellite signals and continually updated the aircraft's position in real time on a pilot display. Preprogrammed exposure data coordinates were sent to the camera via the ASMS providing accurate image acquisition. Every time the DMC captured an image, a signal was sent to the laptop computer and the position of the aircraft at the time of exposure was determined and logged. Differential ABGPS was used during the acquisition of aerial imagery. Airborne GPS collection procedures were as follows: 1. Dual-frequency survey-grade receivers were used for ground and camera stations. 2. The collection rate was 1 second and was matched in both ground and airborne receivers. 3. The elevation mask was set to 0 degrees. 4. Minimum number of satellites required: 5 5. Initialization of GPS data collection by both stations 5 minutes prior to takeoff with the aircraft stationary. 6. GPS data collection was continued during fuel stops (if necessary). 7. Maximum bank angle was 25 degrees or the maximum possible bank without loss of lock. If a loss of lock was observed during a turn, the approach to the next line was extended to allow 20-30 seconds to give the position calculations time to stabilize. 8. Data collection was continued after the mission until the aircraft was stationary for a minimum of two minutes. CONTROL_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated False MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated 5700 Broadmoor Street Mission Kansas 66202-2402 mhardensales@geoeye.com US (913) 981-9600 (913) 981-9602 09.00 to 17.00 Central Time Business is conducted Monday through Friday, except on holidays. 2) Fully Digital Analytical Aerotriangulation (FDAAT) The FDAAT process physically and mathematically ties individual digital images and associates the entire photographic set with the project's horizontal and vertical datums. FDAAT software corrects inherent systematic errors such as earth curvature, atmospheric refraction, camera lens distortion and aircraft (flight) inconsistencies. The FDAAT process calculates the exterior orientations for each camera station (x, y, z location at the photo center and tip, tilt, and swing of the camera station at the instant the digital image was captured). The exterior orientations were used to set models during the stereo compilation phase. The vendor used Image Station Automatic Triangulation (ISAT) for digital mensuration. During this process, image coordinates of all tie, control, and check points in the imagery were measured and a "least squares bundle adjustment" was performed. This process yielded exterior orientation parameters for all imagery and three-dimensional object coordinates for all measured image points. The results of this method look very similar to that of traditional triangulation, but without the marked diapositives. There were nine to fifteen pass points and tie points per digital image generated. ISAT combined aerial photo mission data and GPS base station data session as input into the automatic aerial triangulation process. Independent digital imagery block measurements and adjustments were performed, as well as overall project block measurements. Reports were generated and the data was readied for the next step of the compilation process. A digital photogrammetry application was used that applied image matching techniques to automate the point transfer and the point mensuration procedures to automatically extract tie points. Measurements created by the aerial triangulation software were analyzed by matching coordinates in each image. If any high residual errors occurred, they were either taken out or measured and resolved. The image and ground coordinates for a group of photographs were adjusted to fit a mathematical model within specified project tolerance limits. To ensure consistent results, a second iteration of the residuals for the control and image points was reviewed. Control points were then introduced into the solution to analyze how the image points tied together. CONTROL_2012, DMC_IMAGES_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated FDAAT_SOLUTION_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated 3) Digital Orthophoto Generation There were three main steps in the creation of digital orthophotos for Cook County. They were: Import of the Digital Terrain Model Fully differential orthometric rectification Radiometric correction and image mosaicking Merrick used the INPHO suite of OrthoMaster and OrthoVista for the development of digital ortho-image map documents. MJ Harden used Intergraph's OrthoPro. Both systems/processes used the same basic condition to identify an image pixel of a ground point on the digital terrain surface and then "project" it to its true orthographic position. Input Validation and Setup The project area was subdivided into workable blocks for efficient processing (up to 50 stereo models per block). DTM data was merged for a given block and the elevation data was graphically displayed relative to the project boundary to ensure that all areas would be correctly rectified. Since orthophotos are only as accurate as the rectification surface on which they are based, rigorous quality control procedures were enacted to ensure that the DTM and consequently the orthophotos met or exceed specifications. The DTM was evaluated using various isometric views that check for any "spikes". The technician also validated that the DTM blocks overlapped to ensure that there were no data gaps between the blocks. A Triangulated Irregular Network (TIN) was generated from a DEM. Project parameters (photo scale, camera calibration data, output resolution, etc.) were input to a project file for access by the processing software. Interior orientations (fiducial measurements) were imported from the stereo compilation department to alleviate the need for re-measurement and maintain consistency between the compiled data and final orthoimagery. Minifying (re-sampling) the scanned imagery created a reduced resolution data set. The reduced resolution data set was used for the initial rectification. Image Rectification and Processing Establishing or defining the ground surface and digital image relationship via digital orientation was the next steps in the process. Digital images were georeferenced to the DEM surface through an interior (from the camera calibration report) and exterior orientation (from the FDAAT) of the scanned image. These orientations related the scanned image to the camera and, subsequently, the camera to the ground. Software processes were executed to simultaneously rectify and mosaic an entire block of digital imagery. This process was completed on the minified data set as an initial rectification to expedite processing. Merrick used a Cubic Convolution re-sampling method, with the ability to edge-enhance or smooth an image as needed to arrive at the best geometric and radiometric output possible. Seam lines were automatically generated by the software and displayed to the technician. Tone and contrast were adjusted automatically between input images during this process, with the images then feathered across a buffer zone to eliminate seam lines within the project area. The ortho technician reviewed the location of the seam lines and manually modified them to avoid height objects and to place them in monotone areas (through open field, along road centerlines, etc.). The technician also reviewed the image characteristics and modified a block-wide histogram as necessary to adjust the overall tonal balance. A second and final rectification was completed on the full resolution data set using the modified parameters and edited seam lines from the initial adjustment. Tonal balancing on a block basis was again reviewed to ensure consistent imagery. Overall image quality was reviewed to ensure that the imagery was of consistent tone and contrast across the project area, and to specifically look for any breaks or processing failures within the image. Any such breaks were cause for rejection and recreation of the affected sheets after determining the nature of the problem. Blocks of imagery were cut to individual delivery tiles. For this project, the tiling characteristics were as follows: > Ortho scale: 1"=100' > Tile size: 2,500' x 2,500' > Number of tiles: 18,905 > Pixel resolution: 0.5' > Tile Size: 100MB A visual inspection of each tile was completed for aesthetics. Bridges were corrected by rectifying them at "zero" elevation. The rectified feature is referenced and transferred to the final image file. Seamless Ortho Mosaic Methodology There are several methods available to deal with the photographic repercussions of the radial properties of aerial cameras. The approaches used in this project were to utilize spot shots over the tallest buildings and the most centered portions of each exposure. The objective behind this approach was to eliminate as much as possible the loss of ground detail caused by building displacement. Imagery from the "Special Consideration Area" was used to realize this objective. This set of digital imagery was acquired with excessive side and forward overlap. Significant overlap allowed orthoimagery to be created from an image where the buildings are close to, or, at nadir. Buildings located at nadir would exhibit little or no "lean". This process began with Merrick's digital ortho technician "pre-selecting" which images had the smallest amount of building "lean". The images that were selected were added to the mosaic using a "single image resection" process. This process used points that were common to the selected images and those previously used in the FDAAT solution. The common points became the "registration" points used in the mosaic. Once the pre-selection and single photo resections were completed, the selected images were rectified and mosaicked together. To minimize the effect of inherent tonal variations from image to image, ortho technicians reviewed and modified seam lines so that they were placed in areas of consistent tonal balance and between buildings or bridges. A dynamic range adjustment was completed across the entire block of images to provide a tonally balanced product. Mosaicking parameters were carried from block to block to ensure that the entire project area had consistent tonal qualities. Final Digital Ortho Formatting Final image quality and geometric fit was reviewed before translation to Continuous Tone, GeoTIFF Class G format files. Once translation occurred, the translated images were displayed to ensure no errors had occurred in translation. The images were then written to the specified media for delivery to the client, and were backed up with all related project data to assure data recovery for future operations. FDAAT_SOLUTION_2012, DMC_IMAGES_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated DIGITAL_ORTHOPHOTOS_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated 4) Quality Control Process Airborne GPS QA/QC All ABGPS projects were flown with at least two ground stations. All ground stations were set up at pre-determined, multipath free locations. Multiple ground stations provided data redundancy, which allowed for processing from one ground station to the other. During the flight, all ground stations were monitored and interruptions in operation were conveyed to the flight crew via radio. Onboard the aircraft, GPS lock was monitored on the Trimble survey controller. End-turns were kept to a 20-degree bank or less to reduce the risk of losing initialization. At the end of each day's mission, all data was copied onto laptops creating multiple copies. Post processing was done using a 15 degree mask angle, using the best satellite configuration for that day. The final submitted post-processed file was the combined product of forward and reverse processing. Fully Digital Analytical Aerotriangulation QA/QC The Root Mean Square (RMS) error results of the interior orientations were reviewed by the aerotriangulation technician for compliance with a set standard, which is less than ten microns. Potential autocorrelation matching errors were automatically flagged by the software and resolved by the aerotriangulation technician. The analytical technician reviewed the soft-pugged scanned imagery to verify that not less than one tie point per stereo model was common to the adjacent flight line, and that each stereo model contained no less than six pass points. During point mensuration on the softcopy analytical stereoplotters, independent model solutions were computed, and refined image coordinates were checked to ensure that no point exceeded 10 microns of error. During the mensuration process, the analytical technician checked for the presence of gross errors, and took preventative measures during the intermediate adjustment procedures. Ground control checkpoints were used to verify ground control survey and aerotriangulation. After the accuracy was verified, the checkpoints were then included in the final aerotriangulation and all subsequent stereo model setups. The aerotriangulation technician thoroughly reviewed the residual and RMS error results of the ABGPS, ground control and terrain (matched) points from initial and final adjustments to ensure that the results would support the accuracy requirements of the project. The final bundle adjustment is reviewed by an aerotriangulation technician, discipline lead, project manager, and a Certified Photogrammetrist (CP). An Aerotriangulation Report was generated, reviewed and signed by the discipline lead, project manager and a Certified Photogrammetrist. DEM editing QA/QC The digital terrain data was processed by operators through proprietary software that verified feature coding to compilation criteria. Automated routines were used to process the digital elevation data and verify model-to-model scan row connections and ridge-and-drain line snapping. The operator interpreted this data when inspecting the elevation data for errors. The seamless elevation database was visually verified by the CAD operator to ensure that all stereo models had been integrated. Each level was also edited to verify model-to-model edgematching and completeness. A sampling of contour plots was generated to also validate the DEM. The plots were inspected for completeness and spot elevations were added independently to verify that contour interpolation was performed correctly. Digital Orthophoto Image QA/QC Images were thoroughly reviewed by the digital imaging discipline lead for clarity, contrast, shadow detail, and sunspots. The clarity of the images can be significantly affected by atmospheric haze and dust. Therefore, imagery was taken in accordance with ASPRS Standards for Aerial Photography whereby the "photography shall not be secured when the ground is obscured by haze, snow, smoke, dust, flood waters, or environmental factors that may obscure ground detail." The imagery was thoroughly reviewed for compliance with this standard. The DEM was evaluated using various isometric views to check for "spikes". DEM data were merged for a given block and the elevation data was graphically displayed relative to the project boundary to ensure that all areas would be correctly rectified. Ortho technicians validated that the DEM blocks overlapped to ensure that there were no data gaps between blocks of imagery. Ortho technicians reviewed the locations of seam lines and manually modified them to avoid height objects and placed them in monotone areas (through open field, along road centerlines, etc.). Ortho technicians reviewed the block-wide image characteristics and modified a histogram as necessary to adjust the overall tonal balance. Tonal balancing on a project-wide basis was reviewed to ensure consistent imagery and to specifically identify any breaks or processing failures. A final visual inspection of each tile was completed for aesthetics and anomalies. Visible control points were measured on the final orthophotos and were compared against the values of the survey control coordinates. An RMS error was calculated for all measured control points and compared against the accuracy standards for the project. In addition to the QA/QC steps described above, further checks were made by overlaying the image data with planimetry to check specifically for correct fit, placement, and completeness of the data before final formatting and delivery. DIGITAL_ORTHOPHOTOS_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated QA/QC_DIGITAL_ORTHOPHOTOS_2012 2012-12-01T00:00:00 MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated MJ Harden Associates, Incorporated