2001 Digital Orthophotography
In 2001, the North Central Texas Council of Governments facilitated the purchase of digital aerial photography (orthos) for the following 11 counties in North Central Texas: Collin, Dallas, Denton, Ellis, Hunt, Johnson, Kaufman, Navarro, Rockwall, Somervell and Tarrant.
The contractor for this project was Vargis, LLC. The orthos were collected from February to March of 2001 and lower resolution imagery 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; 3.8 MB]
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. Sample products are available for evaluation of image quality and positional accuracy.
|Sensor Type||Aerial film camera with 6" focal length|
|Negative Size||9" x 9"|
|Altitude of Capture||9,000' above mean terrain|
|Capture Period||February-March 2001|
|Control Sources||Ground survey and airborne GPS|
|Scanning Resolution||15 microns|
|Ground Resolution||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)|