GENERATION OF DEM FROM CONTOURS FOR THE ORTHORECTIFICATION OF HIGH-RESOLUTION STELLITE IMAGES

We present a technique for constructing a digital elevation model (DEM) from contours. The elevation of each ground point in DEM is computed by interpolating the heights of the two adjacent contours of the point. The technique decomposes each sub-domain between adjacent contours into a set of sub-regions. The decomposition is accomplished by constructing a medial axis of the sub-domain. Each sub-region in the decomposition is classified into a variety of terrain features like hillsides, valleys, ridges, etc. The elevations of points are interpolated with different methods according to terrain features they belong to. For a given point in hillside, an approximate gradient line passing through the point is determined and the elevation of the point is interpolated from the known elevations of the two adjacent contours along the approximate gradient line. The univariate monotone rational Hermite spline is used for the interpolation. The DEM constructed by the technique is to be used to orthorectify the high-resolution KOMPSAT3 imagery.