these images have both the verisimilitude of a photograph and the precise spatial attributes of a map. they start out as ordinary arial or satellite photos and then any distortions due to camera tilt or ground topography are aptly removed via computer. so they are totally accurate representations of the earth's surface that can be used to measure exact distances, plan routes, or show features in the landscape. plus they look totally amazing.
[(small photo) detail from an orthophotograph demonstrating earth fissures in the escalante desert in utah. from the utah geological survey. (big photos) top: this is a color-infrared digital orthophoto via the united states geological survey. it shows the platte river valley in nebraska where nine endangered species of birds live. in this context the orthophotos are used to understand the changing mirgatory patterns and ecology of the birds' habitat. middle: digital orthophoto of the south side of mount hood in oregon. from the website of geography professor keith jackson. bottom: orthophoto of the university of arizona campus. used as an educational tool to build virtual environments and 3d models by the college of argriculture and life sciences networking lab at u of a.]