ABSTRACT
The terms target and background may be defined, respectively, as an object to be detected, located, or identified by means of infrared techniques, and as “any distribution or pattern of radiant flux, external to the observing equipment, which may interfere with this process”. Every object in the universe is constantly emitting and receiving infrared radiation from every other object, depending on its temperature, emittance, and the absorptance of its surfaces. While specific radiation characteristics of military vehicles are seldom quoted in the open literature, thermal images provide useful information on heat distribution. The infrared emission from a low-altitude plume is thermal in character; that is, it can be stated in terms of the Planck blackbody function and certain spectral parameters. The best description is a two-dimensional radiance map, but this is valid only for the time at which it was made, for that location, season, weather, and so on.
