Roger Holmes
Opt. Eng. 9(2), 090252 (1 January 1971) doi:10.1117/12.7971572
TOPICS: Data processing, Sensors, Optical instrument design, Earth's atmosphere, Atmospheric optics, Atmospheric physics, Transmittance, Imaging systems, Photovoltaics
The basic physical quantity measured by earth resources survey optical instrumentation is the average scene spectral radiance in a field-of-view patch, modified by atmospheric transmittance. Often this spectral radiance is integrated over a band of wavelengths; the sensor then yields a band average of spectral radiance. Primary additional information is contained in the spatial distribution of this radiance, i.e., the scene geometry, and the time of day and year of the scene record. These statements apply to the broad class of photoelectronic imaging systems, including emulsion, photocathode, photovoltaic, and photoconductive sensors in a variety of scanning and non-scanning instruments.