Method and apparatus for generating a texture mapped perspective view

Abstract

A method and apparatus for providing a texture mapped perspective view for digital map systems. The system includes apparatus for storing elevation data, apparatus for storing texture data, apparatus for scanning a projected view volume from the elevation data storing apparatus, apparatus for processing, apparatus for generating a plurality of planar polygons and apparatus for rendering images. The processing apparatus further includes apparatus for receiving the scanned projected view volume from the scanning apparatus, transforming the scanned projected view volume from object space to screen space, and computing surface normals at each vertex of each polygon so as to modulate texture space pixel intensity. The generating apparatus generates the plurality of planar polygons from the transformed vertices and supplies them to the rendering apparatus which then shades each of the planar polygons. In one alternate embodiment of the invention, the polygons are shaded by apparatus of the rendering apparatus assigning one color across the surface of each polygon. In yet another alternate embodiment of the invention, the rendering apparatus interpolates the intensities between the vertices of each polygon in a linear fashion as in Gouraud shading.