What is Remote Sensing?
Ask twelve experts for a definition of remote sensing and you will get fifteen definitions. With that caveat, I will offer what I consider a reasonable definition. Remote Sensing is "the practice of obtaining data on a target, using distantly placed detection devices." Such devices, often mounted in aircraft or satellites, may detect radiation at a number of wavelengths in order to infer characteristics of the emitting or reflecting object. The characteristics that can be learned about an object include surface temperature, composition, structure, and size.
Remote sensing can also be used to determine the distances to objects (for example, GPS, Rangefinders, and LiDAR). This kind of application is not the focus of this paper, but there will be a few references to these and related technologies here and there.