Contour-to-grid interpolation with nonlinear finite elements : a feasibility study

Abstract : This report concludes the second phase of a three-phase collaborative effort between the U.S. Army Engineer Topographic Laboratories and the National Bureau of Standards. The main objective of this effort is to develop and implement a contour-to-grid algorithm, that is, an algorithm capable of converting digitized contour data into Digital Terrain Elevation Data (DTED). The approach is to create a synthetic terrain surface based on digitized contour information and then to calculate any grid from that surface. Five tasks are to be performed: 1) Edit a digitized contour data set (input); 2) Thin (reduce, sample) the input data; 3) Triangulate the selected points; 4) Generate a smooth synthetic surface; and 5) Generate the desired grid. The first phase, which was completed in December 1985, addressed the first three tasks. The second phase, to which this report refers, elaborates on the previous results and includes work in all five areas. The effort demonstrates the feasibility of performing such tasks for large data sets, such as a Digital Graphic Recorder data tape of roughly 500,000 points.