Definition and Purpose:
DEM stands for Digital Elevation Model. They are a type of Raster file which arranges information like a checker board, each square being a pixel. Each pixel has its x-y coordinates specified in addition to a third value which codes the main attribute of the data. That attribute could be any thing that varies in space, such as: population, rainfall, vegetation index, chemical concentration or elevation.
A DEM is a raster file that codes elevation. Besides creating compelling physiographic landscapes, as shown the banner above, DEM's like other raster files lend themselves to analysis. In fact, the physiographic character of the image above is the result of an analytical process called "Hillshading." Below are a series of images that show raw DEM's in addition to a few basic analytical products.
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