Development Of DEM Program And Application Based On Visual LISP And VBA

Measuring method and counting computational accuracy of earth volume is one of the study content of engineering surveying in engineering mapping. Earth volume takes a large scale in the early construction procedure, and CAD shows a strong advantage in calculating earthwork. With the fast development in computer technology, the strong function advantages of CAD technology show more and more in all kinds of construction application nowadays. So, it’s necessary to open a new high-accurate DEM software based on CAD platform to calculate earthwork.Visual LISP is based on CAD platform, and has good portability, extent possibility and engineering calculation visualization. The text introduces the Visual LISP language based on CAD and combining VBA strong functions to achieve drawing of arbitrary discrete points of irregular triangle net, and achieve drawing of contour line according to triangular irregular network, based on the contour line drew, achieve drawing of any direction section line profile, which has solved the earthwork calculating problem of triangular irregular network and regular grid.Taking Jiujiang plain discrete point data for example, aiming at regular grid interpolation problems which influence the precise earthwork calculation, and analyzing regular grid separation distance and average field area, giving a seasonable separation distance to acquire a precise earthwork results which compared to the traditional calculation methods. The results show, opening a program using regular network to calculate earthwork can meet the requirements of accuracy which higher than the traditional calculating method. The study results have a practice guiding significant to the relative application for triangular irregular network and regular grid.