Untar the file with: tar -xvpf DEMO.tar
Disclaimer: This SG3d program module was compiled to run without installing GRASS; in order to use SG3d effectively with your own data, you should install and learn to use GRASS. GRASS is a powerful Geographic Information System that allows researchers to use a variety of statistical and spatial analysis techniques to evaluate their data. SG3d helps in this evaluation by providing an easy to use display mechanism to view 2D data as a surface in 3D space. For more information on how to obtain the GRASS GIS software, see GRASS Information.