Remote Sensing

Coined in the 1960s by a geographer named Evelyn Pruitt, the term remote sensing refers to the collection of data about Earth's surface (and atmospheric) features or phenomena without being in direct contact with such features or phenomena. This entry first provides background on electromagnetic radiation (EMR), which is the information link that enables the collection of data about Earth's surface without being in contact with the surface. Next, the entry discusses sensors that capture EMR and are mounted on platforms (aircraft or satellite), which enables the remote collection of different types of imagery. Finally, the principles and strategies of image interpretation for extracting geographic information are covered.

There are advantages and disadvantages in using remote sensing technology for geographic research and applications, relative to more conventional, ground-based or in situ (i.e., direct) observation methods. The primary advantage is that remote sensing enables spatially continuous and contiguous, large-area sampling of Earth's surface and atmosphere. This means that data are comprehensive, synoptic (i.e., many features are observed simultaneously), and efficiently collected. Other advantages are the noninvasive, nondisturbing nature of sensing remotely and the ability to collect data for areas that are inaccessible or inhospitable for making observations on the ground. Often, historical information on geographic features or [Page 2415]conditions can only be derived through interpretation of archived imagery captured in the past. The main disadvantages of remote sensing are that remote observations are less detailed and precise and more uncertain than direct measurements made on the ground. Also, the sensing process, the image-processing steps, and the act of image interpretation all can yield more artifacts (i.e., false information) than would normally result when making in situ observations.