Terrestrial surfaces are composed of a diverse assemblage of human-made materials such as concrete, asphalt, and metal and natural materials such as soils, shrubs, and trees. Scientists observe such features on the surface of the Earth and make measurements to better understand the characteristics associated with them. This entry describes the nature of research using remote sensing and examines the spectral characteristics of vegetation, soil, water, and human-made materials.

Characterizing and monitoring the materials through time is very important for many Earth resource management applications. While the tasks are often conducted by taking detailed field measurements, the process is time and labor intensive and is often difficult to conduct over large geographic areas. Remote sensing, which collects information about a feature without being in direct physical ...