The bounds of the output map are limited by the current region (see g.region).
The -a flag can be used to create a Voronoi diagram for areas.
The -s flag can be used to extract the center line of areas or skeletons of areas with thin >= 0. Smaller values for the thin option will preserve more detail, while negative values will extract only the center line.
The extraction of skeletons and center lines with the -s flag is a brute force approach. Faster and more accurate algorithms to extract skeletons from areas exist but are not yet implemented. In the meantime, skeletons and center lines can be simplified with the Douglas-Peucker algorithm: v.generalize method=douglas.
g.region -p rast=elev_state_500m v.voronoi in=hospitals out=hospitals_voronoi
g.region -p n=162500 s=80000 w=727000 e=846000 res=500 v.voronoi in=urbanarea out=urbanarea_voronoi -a
g.region -p n=161000 s=135500 w=768500 e=805500 res=500 v.voronoi in=urbanarea out=urbanarea_centerline -s v.voronoi in=urbanarea out=urbanarea_skeleton -s thin=2000
Last changed: $Date: 2013-10-14 09:52:11 +0200 (Mon, 14 Oct 2013) $