Stencil shadow volumes are the main 3D rendering method for vector maps. Basic geometric graphs

such as lines and polygons

are the main representation of map features. These representation forms were so simple that strictly limited map feature information had been transferred. Consequently

in order to enrich the 3D visualization styles of a vector map

an extended rendering method based on the stencil shadow volumes is presented

which realizes real-time symbol overlaying of a vector map on terrain. First

the basics of vector data visualization based on the stencil shadow volume theory are reviewed. Second

the extended method is introduced

which includes border smoothing with rounded caps

while dealing with outlines and overlaps. Finally

the experiment results show that a real-time display of vector maps on terrain can be achieved and that the visualization effects have been improved by cartographic symbolical overlay.