20190921
22511100
1.0
FGDC CSDGM Metadata
FALSE
CreateMosaicDataset \\Gisimgprd1\e\Productionfiles\Ortho_2017\Ortho_2017.gdb Ortho_2017 "PROJCS['NAD_1983_StatePlane_Maryland_FIPS_1900',GEOGCS['GCS_North_American_1983',DATUM['D_North_American_1983',SPHEROID['GRS_1980',6378137.0,298.257222101]],PRIMEM['Greenwich',0.0],UNIT['Degree',0.0174532925199433]],PROJECTION['Lambert_Conformal_Conic'],PARAMETER['False_Easting',400000.0],PARAMETER['False_Northing',0.0],PARAMETER['Central_Meridian',-77.0],PARAMETER['Standard_Parallel_1',38.3],PARAMETER['Standard_Parallel_2',39.45],PARAMETER['Latitude_Of_Origin',37.66666666666666],UNIT['Meter',1.0]];-36747100 -29091500 10000;-100000 10000;-100000 10000;0.001;0.001;0.001;IsHighPrecision" # # NONE #
CalculateStatistics \\Gisimgprd1\e\Productionfiles\Ortho_2017\Ortho_2017.gdb\Ortho_2017 1 1 # OVERWRITE "Feature Set"
BuildMosaicDatasetItemCache \\Gisimgprd1\e\Productionfiles\Ortho_2017\Ortho_2017.gdb\Ortho_2017 # DEFINE_CACHE GENERATE_CACHE \\Gisimgprd1\e\Productionfiles\Ortho_2017\Ortho_2017.Cache\Ortho_2017.Cache LOSSLESS 80 200000 200000 PIXEL_SIZE_FACTOR 1
BuildOverviews \\Gisimgprd1\e\Productionfiles\Ortho_2017\Ortho_2017.gdb\Ortho_2017 # DEFINE_MISSING_TILES GENERATE_OVERVIEWS GENERATE_MISSING_IMAGES REGENERATE_STALE_IMAGES
AnalyzeMosaicDataset \\Gisimgprd1\e\Productionfiles\Ortho_2017\Ortho_2017.gdb\Ortho_2017 # FOOTPRINT;FUNCTION;RASTER;PATHS
Ortho_2017
file://\\OCTO-5GS23W2\E$\ProductionFiles\Ortho_2017\Ortho_2017.gdb
Local Area Network
389400.000000
408600.000000
124200.000000
148200.000000
1
Projected
GCS_North_American_1983
Linear Unit: Meter (1.000000)
NAD_1983_StatePlane_Maryland_FIPS_1900
<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/3.0.0'><WKT>PROJCS["NAD_1983_StatePlane_Maryland_FIPS_1900",GEOGCS["GCS_North_American_1983",DATUM["D_North_American_1983",SPHEROID["GRS_1980",6378137.0,298.257222101]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Lambert_Conformal_Conic"],PARAMETER["False_Easting",400000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",-77.0],PARAMETER["Standard_Parallel_1",38.3],PARAMETER["Standard_Parallel_2",39.45],PARAMETER["Latitude_Of_Origin",37.66666666666666],UNIT["Meter",1.0],AUTHORITY["EPSG",26985]]</WKT><XOrigin>-36747100</XOrigin><YOrigin>-29091500</YOrigin><XYScale>121236910.21292362</XYScale><ZOrigin>-100000</ZOrigin><ZScale>10000</ZScale><MOrigin>-100000</MOrigin><MScale>10000</MScale><XYTolerance>0.001</XYTolerance><ZTolerance>0.001</ZTolerance><MTolerance>0.001</MTolerance><HighPrecision>true</HighPrecision><WKID>26985</WKID><LatestWKID>26985</LatestWKID></ProjectedCoordinateSystem>
8
FALSE
None
4
AMD
TRUE
continuous
unsigned integer
4100
15000
1000
20
2048
20
75
0.01
10
600
300
Basic
1
NorthWest,Center,LockRaster,ByAttribute,Nadir,Viewpoint,Seamline,None
None,JPEG,LZ77,LERC
None
None,Basic,Base-Top Height,Top-Top Shadow Height,Base-Top Shadow Height,3D
-1
-1
0.8
1
NorthWest,Center,LockRaster,ByAttribute,Nadir,Viewpoint,Seamline,None
None,JPEG,LZ77,LERC
None,Basic,Full
NONE
Name,MinPS,MaxPS,LowPS,HighPS,Tag,GroupName,ProductName,CenterX,CenterY,ZOrder,Shape_Length,Shape_Area
8748
0.08
174.96
0
<_docversion_ Sync="TRUE">9
20231003
16534900
20231003
16560700
150000000
5000
FGDC
GIS Data Coordinator
D.C. Office of the Chief Technology Officer
(202) 727-5660
200 I Street SE, 5th Floor
Washington
DC
20003
US
dcgis@dc.gov
8:30 am - 5 pm
20231003
ArcGIS Metadata
1.0
GIS Data Coordinator
D.C. Office of the Chief Technology Officer
(202) 727-5660
200 I Street SE, 5th Floor
Washington
DC
20003
US
dcgis@dc.gov
8:30 am - 5 pm
DC datasets can be downloaded from "http://opendata.dc.gov".
Image Service
Ortho_2017
2017-09-13
DC GIS
200 I Street SE, 5th flooe, Washington, DC, 20003, US
remote-sensing image
<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>2017 Orthophoto - 3 inch resolution: This document describes the processes used to create the orthoimagery data produced for the District of Columbia from 2017 digital aerial photography. It was flown in early March, completed on March 8, 2017. DUE TO TECHNICAL DIFFICULTIES, THE DOWNTOWN AREA IS NOT COMPRISED OF TRUE ORTHOIMAGERY. THE CONTRACTOR MINIMIZED BUILDING LEAN USING THE INCREASED SIDELAP OF IMAGERY. The aerial imagery acquisition was flown to support the creation of 4-band digital orthophotography with a 3 inch/0.08 meter pixel resolution over the full project area covering the District of Columbia which is approximately 69 square miles. The contractor received waivers to fly in the Flight Restricted Zone (FRZ) and P-56 areas. The ortho imagery was submitted to DC OCTO in GeoTiff/TFW format tiles following the tile scheme provided by OCTO. MrSID and JPEG2000 compressed mosaics were delivered as well using a 50:1 compression ratio.All DC GIS data is stored and exported in Maryland State Plane coordinates NAD 83 meters. METADATA CONTENT IS IN PROCESS OF VALIDATION AND SUBJECT TO CHANGE.</SPAN></P></DIV></DIV></DIV>
This data is used for the planning and management of Washington, D.C. by local government agencies.
GIS Data Coordinator
D.C. Office of the Chief Technology Officer
(202) 727-5660
200 I Street SE, 5th Floor
Washington
DC
20003
US
dcgis@dc.gov
8:30 am - 5 pm
Geographic Names Information System
D.C.
Washington
D.C.
District of Columbia
United States of America (USA)
Orthophotography
Planning
Imagery
Orthos
Aerial Photography
imageryBaseMapsEarthCover
ISO 19115 Topic Categories
imageryBaseMapsEarthCover
Orthophotography
Planning
Imagery
Orthos
Aerial Photography
imageryBaseMapsEarthCover
imageryBaseMapsEarthCover
D.C.
Washington
D.C.
District of Columbia
United States of America (USA)
<DIV STYLE="text-align:Left;"><DIV><DIV><P><SPAN>This work is licensed under a Creative Commons Attribution 4.0 International License.</SPAN></P></DIV></DIV></DIV>
See access and use constraints information.
Esri ArcGIS 10.3.1.4959
true
-77.122373
-76.900716
39.001746
38.785481
The aerial photographic mission was composed of 81 flight lines in three flight line classifications: ADS, ADS-P56 and ADS-5in. The ADS and ADS-P56 lines collected 3 inch data at an average altitude of 3,020 feet above mean sea level, the 5 inch lines were used to get full coverage over restricted areas was flown at an average altitude of 5,400 feet above mean sea level. Data was collected on the following days in three lifts: Lift 1 - March 4 2017, P56 lines 1-12; Flight 2 – March 5 2017, P56 lines13-33, 5 inch lines 1-3, ADS lines 1-5, 11, 26-45; Flight 3 – March 8, 2017 ADS lines 6-10, 12-25. The data was flown with increased sidelap in the downtown areas for building lean reduction. The lines had multiple orientations to accommodate the restricted areas while still maintaining full coverage of the project area. Twenty-seven lines were flown oriented east/west, 34 were oriented north/south, and 20 were flown at angles to accommodate the P-56 areas.
All data were collected using Cessna 441 Conquest II twin tubroprops, Leica ADS100 digital pushbroom sensor #527. Due to the known difficulties flying over DC, the ADS100 sensor was selected to take advantage of its flight altitude and speed to minimize the number of lifts for the various flight restrictions. Aerial photography was collected in conjunction with airborne GPS.
1
-77.122373
-76.900716
39.001746
38.785481
Quality control procedures were implemented and documented at each step of the project to ensure that all services required by the contract are completed to specification; they include visual (manual) inspections, automated routines, and technical reviews.
Aerial Data Acquisition QA/QC: 1. Flight Planning - The flight plan was based on the scope of work (SOW), DC OCTO provided boudnary, and flight restrictions.
2. Ground GPS Acquisition - The GPS equipment was assembled on a monument or a temporary established point and data was recorded. The data was then checked to ensure the PDOP is less than 3.0.
3. Data Acquisition
Prior to full flight, the following steps was peformed: - Inspect storage and system components to ensure all units are operational and there is sufficient storage space
- Select and confirm the lever arm coordinates
- Load navigation system and perform system check
- Perform 5 minute static alignment and record PDOP, GPS, and UTC start time
- Ensure IMU is operational
- Ensure all channels are operational, as applicable.
After the pre-flight checks, the crew began flight line data recording: observe video display, POS status and mass memory screens; record UTC start/stop times, GPS data, ground speed, altitude, comments/concerns, lines, waypoints and times on the flight log. When the flight mission was completed, a 5 minute static alignment was performed followed by a systematic shutdown of the system. All collected data was downloaded for QC.
Ground Control QA/QC:
The Ground Control QA/QC strategy is based on reviewing the criteria described below:
- Incidences of High PDOP
- Poor network closure
- Inadequate point location
- Missing or omitted points
- Damaged or missing panels
The evaluation of the ground control is done through the following steps:
- All planning, reconnaissance, field observations, post-processing, adjustments, and final report development will be performed under the direct supervision of a highly-experienced land surveyor.
- Fixed height tripods will be used during the GPS survey to eliminate antenna height measurement error.
- The field crews will perform processing and closure analysis of the data to eliminate field blunders and determine baselines, which do not fit the network or project tolerances and must be re-observed.
- The final adjustment and processing of target locations will be coordinated, directed and completed by a single surveyor to ensure the overall consistency and integrity of the control network required to accurately map an area of this size. These efforts will also facilitate a smoother aerial triangulation process.
IMU/GPS Processing QA/QC:
Airborne GPS control is accomplished through the simultaneous observation of five or more satellites in the GPS constellation using the on-board receiver and one or more ground receivers (base stations) located over known control points that are in the vicinity of the project area.
If accessible to non-airport personnel, the GPS occupation of a primary airport control station (PACS) is established prior to any airborne GPS collection. A GPS receiver is placed on a temporary marker using PK nails to define the location. The GPS station records at a one second interval for the duration of the airborne collection. Coordinates for this base station point is adjusted by the project surveyor and is tied into the project control network. Airborne GPS and IMU data is immediately processed using the airport GPS base station data. When necessary, combination of CORS stations and surveyor established GPS stations are used to ensure that a base station is operating within range of the aircraft at all times. If this occurs, it is included in the pre-planning. Once a decision has been made to fly, any GPS stations established for the project area is activated at a one second interval for the duration of the airborne collection.
Aerotriangulation QA/QC:
The Aerotriangulation QA/QC strategy is based on the criteria described in the table below:
- Missing or corrupt ground control information
- Camera calibration
- GPS and IMU data integrity
An initial bundle/block adjustment is developed for each data sortie. The accuracy of each bundle/block is confirmed through an RMSE evaluation against the project ground control. The accuracy is verified through an iterative process where the adjustment is repeatedly run, while progressively increasing the constraints on the ground control.
After the accuracy is verified, the technician applies the bundle adjustment result to the images of each AT block (consisting of multiple lifts or sorties). The results of the adjustment are verified through the generation of the full-resolution panchromatic orthophoto chips over the ground control points for the data sortie. The orthophoto chips are inspected by the photogrammetric technician to identify any errors in the adjustment to ensure the accuracy meets project specification. The technician also generates and visually reviews that orthophoto strips cover across all flight lines to ensure edge matching between flight lines.
The adjustment/inspection process is repeated as bundle/block adjustment for adjoining sorties are complete and these small blocks are adjusted to build the overall bundle adjustment. Throughout the process, the accuracy of each adjustment is checked against the GPS ground control points.
Imagery and Orthophoto QA/QC:
The Orthophoto Rectification QA/QC strategy is based on the criteria described below:
- Edge matching
- Fit to ground control
- Radiometric consistency
- Insufficient coverage
- Correct color band rendition
Preliminary field data is reviewed to ensure that there are no gaps between flight lines before the flight crew leaves the project site. Data will be inspected for turbulence, and if it is present and affects the data quality, the line is rejected.
A full visual review is conducted in the office to ensure that it is complete, uncorrupted, and that the entire project area has been covered without gaps between flight lines. The technician performs visual inspection of raw images on selected bands of each collected flight lines for completeness, this step also ensures proper sensor function of the sensor. The flight line trajectory files are reviewed to ensure completeness of acquisition for project flight lines, calibration lines, and cross flight lines.
The raw RGB images for each collected flight lines are rectified using the DEM data and the GPS/IMU solution in Fugro proprietary software. The technician visually reviews all rectified images to ensure completeness of acquisition for all flight lines. The technician also uses these images to identify any gaps, clouds, shadows and any un-predicted issues in project area.
The orthophoto production process incorporates the ability to develop a completed digital orthophoto mosaic of all or part of a data sortie at a greatly reduced resolution. “Quick look” generation permits the quick assessment of iterative adjustments to finalize the parameters that are applied to the data for radiometric corrections to the orthophoto while data limiting computer resources by only processing the imagery at full resolution once. Quick looks also enable the technician to assess the accuracy of the processed imagery as well as identifying areas of distortion that would necessitate regeneration of the DEM or aerotriangulation data.
The imagery is visually checked for accuracy on the workstation screen, and its absolute accuracy is verified by overlaying and comparing the locations of the control that are visible on the image against a CAD file containing the point locations in vector form.
The edge matching of adjacent strips of imagery is accomplished using a single color band from adjoining strips of imagery displaying each strip in alternating colors of red and cyan. In areas where the overlapping images are coincident, the imagery appears in a gray scale rendition while any offset is colored red or cyan. Any offsets are measured to confirm that the offset falls within the accuracy specification for the project.
Using the parameters developed from the quick look, the finishing department radiometrically corrects the orthophotos prior to completing the mosaicking and clipping of the final tiles, then the files are returned to digital orthophoto production for mosaicking. The finishing department performs a 100% final visual check for orthophoto image quality prior to outputting the approach data to the designated media.
AGPS/Aerotriangulation Step: A total of 14 orthophoto ground control points were acquired. GPS was used to establish the control network. The horizontal datum is provided in both the North American Datum of 1983. The vertical datum was the North American Vertical Datum of 1988 (NAVD88) using GEOID12B.
The Leica XPro software (v. XPro 6.1.4) was used for downloading and preparing imagery collected with the ADS100 Airborne Digital Sensor for softcopy photogrammetric use. Using the Leica Geosystems IPAS software package, the GPS data was differentially processed against a base station. After the differential GPS solution was checked and verified, the Leica Geosystems IPAS program was used to compute an integrated GPS/IMU navigation solution. Utilizing the camera calibration the GPS/IMU trajectory was computed using the Leica Geosystems IPAS software. XPro computed a full x, y, z, omega, phi, kappa exterior orientation of each scan line. A fully automatic XPro aerotriangulation process was performed to minimize the residual errors in the GPS/IMU derived exterior orientations. The aerotriangulation also allowed the introduction of ground control and checkpoints to ensure the accuracy specifications were achieved. Stereo imagery (level 1 georeferenced imagery) was created by applying the aerotriangulation solution to the raw imagery. This resampling removes aircraft motion and provides epipolar geometry imagery for stereo viewing. Low resolution images were created to determine the radiometric correction for each lift of imagery. Those settings were then used to create full resolution imagery strips.
2017-09-13
FUGRO GEOSPATIAL, INC.
7320 Executive Way
Frederick
Maryland
21704
US
DEM Step: Upon the completion of the Aerotriangulation, a DEM is generated for the rectification of the imagery. Initially Fugro attempted to create the DEM from existing high density lidar provided by DC OCTO. After reviewing the lidar data Fugro determined the level of effort required to clean the lidar surface would not be efficient so an SGM (semi-global-matching) process was used in the XPro software to generate a surface from the imagery. The surface was then edited to remove artefacts to improve the rectification. The ortho-rectified strips (each flight line) are then mosaicked together using proprietary image database and mosaicking software. The database was edited using Photoshop and QA/QC'ed for coverage, seam lines, smears, and other artefacts. The imagery was clipped out of the database into the sheet layout generated based on client requirements. In the clipping stage, the coordinate system and georeferencing was embedded into the header of the files.
2017-09-13
FUGRO GEOSPATIAL, INC.
7320 Executive Way
Frederick
Maryland
21704
US
3
300000
0.080000
240000
0.080000
1
1
0
389400.000000 124200.000000
389400.000000 148200.000000
408600.000000 148200.000000
408600.000000 124200.000000
399000.000000 136200.000000
EPSG
4.5(3.0.1)
Band_1
255.000000
0.000000
8
Band_2
255.000000
0.000000
8
Band_3
255.000000
0.000000
8
Band_4
255.000000
0.000000
8