| Digital Terrain Model |
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A digital terrain model (abbrev. DTM ) is a topographic Model of the bare earth that can be manipulated by Computer Program s. The data Files contain the Elevation data of the Terrain in a digital format which relates to a rectangular Grid . Vegetation, Building s and other cultural features are removed digitally - leaving just the underlying terrain. DTMs are used especially in Civil Engineering , Geodesy & Surveying , Geophysics , Geography and Remote Sensing . The main applications are: # Visualization of the terrain ( Block Diagram s etc.) # Calculation of Project data or Rock masses in Civil Engineering # Reduction (terrain correction) of Gravity measurements ( Gravimetry , Physical Geodesy ) # Terrain analyses in Cartography and Morphology # Rectification of or Satellite photos. The most usual grid ( Raster ) is between 50 and 500 meters. For several applications in (1)-(3) a full resolution is required only for the central areas of the project. Therefore the huge data amount is reduced by a mix of two or three raster spacings. In gravimetry e.g., the primary grid may be 50 m, but is switched to 100 or 500 meters in distances of about 5 or 10 kilometers. A digital terrain model may be used to guide automatic machinery in the construction of a physical model, the Relief Map . EXTERNAL LINKS |