Produce the prism map. MIDPOINTS= specifies three response levels for the map. XLIGHT= moves the light source to the right and adds shadows to the left-side polygons of the prisms. XVIEW= and ZVIEW= shift the viewing point to the right and upward, respectively. This reduces the number of prisms that are partially hidden by taller neighbors. 
proc gmap map=maps.us data=reflib.sites;
   id state;
   prism sites / midpoints=25 50 75
                 xlight=5
                 xview=.75
                 zview=5
                 legend=legend
                 coutline=gray;
run;
quit;