DOQQ

http://www.tceq.texas.gov/gis/doqtnrcc.html
DOQQs, Digital Orthographic Quarter-Quads, are fused images with characteristics of an aerial photograph and the geometric context of a map. Like DRGs and DEMs, they use raster format to store data. The images have been orthorectified from a distorted aerial photograph to a flat map, allowing for more accurate measuring of distance, angles, shape, area, and positions. This image of the football stadium at the University of Texas, Austin, is a DOQQ as it is and aerial shot of the area, and it's false infra-red color helps to delineate the photograph and orthorectify the image.