1m pan (gray-scale)
or CIR (color infra-red) ortho-rectified aerial photography. Near
full-coverage for the continental US, majority coverage for Puerto
Rico, limited coverage of Alaska (satellite
imagery available for other areas). Rapid delivery and below-USGS
Digital Ortho Quarter Quads (DOQQs) are created by scanning an aerial
photograph. Using a scanning aperture size of about 25 microns
(about one-third the diameter of a human hair), the computer digitally
compares the raster image with the corresponding Digital Elevation
Model (DEM) to mathematically adjust the image, pixel by pixel.
This is a fast and effective way to eliminate ground displacement
caused by airplane tilt and the perspective view of the photograph-
that is, the camera is not being directly over every object in
Each DOQQ covers an area of 3.75 minutes of
latitude by 3.75 minutes of longitude (roughly four miles by four
miles). The imagery is geo-referenced so that other digital map
layers can be overlayed on it, and the data meets 1:12,000 NMAS
(National Map Accuracy Standards, equivalent to 10m CE 90).
DOQQs have between 50 and 300 meters of over-edge,
sufficient for mosaicing after re-projection. LAND INFO offers
a variety of value-added DOQQ processing such as re-projection,
CIR to natural color simulation, CIR to pan conversion, tonal
balancing, mosaic output and compression.