- SPECIAL REPORTS
- THE MAGAZINE
3Di LLC, Easton, Md., unveiled a new website and service - DOQExpress (www.doqexpress.com). Developed for fast delivery of 1 meter, 24-bit color infrared (DIR) Digital Ortho Quadrangles (DOQs), DOQExpress currently serves high-resolution digital aerial photography from Texas, with plans to expand the available data to the continental United States, Alaska and Puerto Rico. Value-added services such as reprojection, mosaicing, resampling and color balancing, are also offered on the site.
Using online order processing, searchable by quad or county name, Texas DOQs can be delivered on CD, with a file size of approximately 150 megabytes per 1 meter, 240-bit CIR image. Currently, DOQ coverage of Texas is at 75 percent, with DOQs from the entire state available by the end of 2000.
As defined by the United States Geological Survey (USGS), DOQs are digital images of aerial photographs in which displacements caused by the camera and the terrain have been removed. A DOQ combines the image characteristics of a photograph with the geometric qualities of a map. The standard digital orthophoto producted by the USGS is a black and white or color infrared 1 meter ground resolution quarter quadrangle (3.75 minute) image. Oftentimes, DOQs need to be manipulated in a variety of ways depending on the user’s needs and other data formats. To address this need, DOQExpress provides additional services to enhance the value and usability of DOQ data. With DOQExpress value-added services, reprojection from UTM to any other projection can be formatted, color balancing and mosaicing can produce visual consistency and seamless integration when combining several DOQs into one image, resolution can be changed from 1 meter to 2.5 meters and higher, depending on the project needs, and finally, viewing speed and storage space can be improved with DOQExpress compression services.
The digital orthoimagery at DOQExpress is derived from National Aerial Photography Program (NAPP) CIR diapositives, acquired in the winter of 1994/95 and updated in the winter of 1995/96. NAPP photography is acquired at 20,000 feet above mean terrain with a 6-inch focal length lens. The flight lines are quarter quad-centered on the 1:24,000 scale USGS maps. NAPP photographs have an approximate scale of 1:40,000.