DEM's Using In 3D Visualizing Of Collapse Pillar Forest And Erosion

A digital elevation model (DEM) is a digital file consisting of terrain elevations for ground positions at regularly spaced horizontal intervals. DEM may be used in the generation of three-dimensional graphics displaying terrain slope, aspect (direction of slope), and terrain profiles between selected points.In this thesis, The author uses DEM for: (1). 3D visualizing of collapse pillar forest based on the data surveyed from working faces and wall rock. The authors configured a data body which can meet to DEM's need. The result shows that this technique is valuable for studying collapse pillar. (2). Estimating long_term erosion rate within the Xishan Coalfield. The calculated total erosion volume is 589Km3 since 500Ma BP, and the erosion rate is 229m3/a, corresponding to a surface lowering of 0.0458mm/a.