2003 Digital Orthophotography
In 2003, the North Central Texas Council of Governments facilitated the purchase of digital orthophotography (orthos) for all 16 counties in North Central Texas. The orthos were collected at 6-inch resolution for Collin, Dallas, Denton, Ellis, Kaufman, Navarro, Rockwall, and Tarrant counties and 1-foot resolution for the remaining counties.
The contractors for this project were Dallas Aerial Surveys and Pixxures. The orthos were collected in February and March 2003 and lower resolution images are available for purchase via the DFWMaps Marketplace according to the following price schedule.
Georeferenced TIFF images are sold in 3,000' x 2,000' tiles, or 0.215 square miles. Sample images and a shapefile of the tile structure may be downloaded below:
2-Foot Resolution Color Ortho Sample [TIFF format with world file; 4 MB]
4-Foot Resolution Color Ortho Sample [TIFF format with world file]
8-Foot Resolution Color Ortho Sample [TIFF format with world file]
The digital orthophotography was produced using accepted photogrammetric industry practices under the supervision of Certified Photogrammetrists and Licensed Surveyors. Digital orthophoto products are guaranteed to meet National Map Accuracy Standards at a map scale of 1"=200' (1:2,400). Photo scale is 1"=1,500' (1:18,000). Products are mosaicked and color balanced to create a near seamless appearance.
|Sensor Type||Aerial film camera with 6" focal length (12" in downtown areas)|
|Negative Size||9" x 9"|
|Altitude of Capture||9,000' above mean terrain (12" focal length)
4,500' above mean terrain (6" focal length)
|Capture Period||January-March 2003|
|Control Sources||Ground survey, airborne GPS, existing DEM, orthos|
|Scanning Resolution||15 microns|
|Ground Resolution||0.5 and 1.0 US Survey Foot|
|Color Type||24-bit Natural Color|
|Coordinate System||Texas State Plane, North Central Zone|
|Horizontal Datum||NAD 83|
|Units||US Survey Feet|
|Format||TIFF or MrSID (1 MrSID tile = 120 TIFF tiles)|