There is no universal usage of the terms digital elevation model (DEM), digital terrain model (DTM) and digital surface model (DSM) in scientific literature. In most cases the term digital surface model represents the earth's surface and includes all objects on it. In contrast to a DSM, the digital terrain model (DTM) represents the bare ground surface without any objects like plants and buildings (see the figure on the right).Li, Z., Zhu, Q. and Gold, C. (2005), Digital terrain modeling: principles and methodology, CRC Press, Boca Raton, FL.
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