In 2015, the North Central Texas Council of Governments facilitated the cooperative purchase of 4-band, 3-inch and 6-inch resolution digital aerial photography (orthos) for over 7,500 square miles of the NCTCOG region including all of Collin, Dallas, Denton, Tarrant and Rockwall counties and portions of Hunt, Kaufman, Ellis, Johnson, Hood, Navarro, Parker, Palo Pinto and Wise counties. 
The contractor for this project was Woolpert.   The orthos were collected in January and February 2015 (leaf-off) and 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:

6-inch Resolution Sample
TIFF orthophotography grid

Specifications

The coverage area for 2015 includes Dallas, Fort Worth, and surrounding urban and rural counties totaling 7,523 square miles, of which 448 square miles is 3” resolution.   Four areas of 6” true orthoimagery were produced over the central business districts of Dallas and Fort Worth, as well as the I-635/US-75 intersection and the Dallas North Tollway corridor from I-635 to Keller Springs Parkway, totaling approximately 24 square miles. 

The flight design achieved a nominal ground-pixel resolution sufficient for developing 3” and  6" pixel orthophotography without oversampling. It was also designed with sufficient forward overlap and strip side laps to ensure total project area coverage.  The final aerial photography meets The American Society of Photogrammetry and Remote Sensing (ASPRS) Class I standard for 1” = 50 and 1"=100' scale mapping. 

3-inch Flight Specifications

6-inch Flight Specifications

More information on the 2015 project can be found in the Project Plan and project level metadata:

3-inch Orthophotography
6-inch Orthophotography
True Orthophotography