DEM

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DEMs, Digital Elevation Models, are yet another product of a U.S. Geologic Survey. They use raster-based image formatting and portray terrain elevation at regular horizontal intervals. They typically have an element of relief to them, in the form of shading or raised lines to produce a three-dimensional image. Observation of this digital elevation model of Switzerland can provide a better understanding of the three-dimensionality of these models, where here you can clearly see where the mountains lie in the country.