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Digital elevation models (DEMs) are three-dimensional maps of an area’s topographical features or surface terrain. They differ from other types of digital terrain models (DTMs) in that they offer continuous elevation data of the various locations included in a mapped area. Thus, terrain maps like contour line maps or topographical maps might be referred to as DTMs but not DEMs. Techniques for creating digital terrain models include remote sensing techniques like satellite and plane imaging, as well as the more traditional method of direct land surveying. DEMs today are used in geographic information systems (GIS) and in consumer and industrial electronic devices and products, like GPS maps and digital location based services offered by cellphone providers. Specific MethodsThe most powerful technique for creating digital elevation models is called the interferometric synthetic aperture radar technique. This is where orbiting satellites take radar images over the course of two passes over the Read more…