Description

DEM/DTM is a digital model or 3D representation of a terrain's surface and most versatile examples of raster data. It contains locations with elevation which can be used in numerous topographical applications. It may be represented as Grid data which includes raster format, interpolated values and have large storage for network analysis or in TIN (Triangulated Irregular Network) data which includes- • irregularly distributed nodes and lines with three dimensional coordinates (x, y, and z) • arranged in a network of non overlapping triangles (triangular tessellation) • Based on Delaunay triangulation • Density of points a variation in surface heights • (+) points provide accurate representation of terrain • (+) fewer points are needed • (-) less suited for analysis of surface slope, aspect and network analysis.