Table 5.1.1 shows various platforms, altitudes and objects being sensed. Platforms with the highest altitude are geosynchronous satellites such as the Geosynchronous Meteorological Satellite (GMS), which has an altitude of 36,000 km at the Equator. Most of the earth observation satellites, such as Landsat, SPOT, MOS etc. are at about 900 km altitude with a sun synchronous orbit.
From lower orbit, there are space shuttle (240-280 km), radio sonde ( - 100 km), high altitude jet-plane ( 10,000 m), low or middle altitude plane (500-8,000 m), radio controlled plane ( - 500 m) and so on.
The key factor for the selection of a platform is the altitude which determines the ground resolution if IFOV (instantaneous field of view) of the sensor is constant, where
The selection of platform also depends on the purpose which is sometime requested for example a constant altitude is required for aerial surveys, while various altitudes are needed to survey vertical atmospheric distribution, for example.
For aerial photogrammetry, the flight path is strictly controlled to meet the requirement of geometric accuracy. However, helicopter or radio controlled planes are used for a free path approach, for example in disaster monitoring.
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