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Stereo Imaging and Geolocation

Stereo imaging serves two purposes. The first is to produce three-dimensional topographic images. These can be used to produce digital elevation models (DEM) and to improve the identification of items of interest. The second is to locate observable points on the ground with respect to a reference geoid (an elliptical surface approximating the mean surface of the Earth). The latter is referred to as geolocation and is the focus of this section. Stereo imaging requires a scene to be viewed from two directions. This can be accomplished with a satellite in one of three ways: with a single camera viewing the scene on different orbit passes (SPOT 1); with a single camera on the same orbit pass by first viewing forward and then viewing aft (IKONOS II); or using a pair of cameras, one viewing forward and the other viewing aft (Corona KH 4B and SPOT 5). These options are depicted in Figure 1.