G. Allegri wrote: > I'm having a problem trying to execute a buffer of 150m on a polygon > generated from a raster with resolution 5x5. > The polygon is a single area, constituted of 1576 vertices (highly > granular). > v.buffer generates 32633 vertices, the it get "mad" building the > topology: it tries to remove intersections, duplicates, etc. giving > the following final result: > > Topology was built. > Number of nodes : 32633 > Number of primitives: 65264 > Number of points : 0 > Number of lines : 0 > Number of boundaries: 65264 > Number of centroids : 0 > Number of areas : 32632 > Number of isles : 1 > Number of areas without centroid : 32632 > > The vector is not readable... > > I don.t know if the problems is due to the buffer algorithm, which > fails because of the pixelated polygon (figure below) > > ____ > | _______ > |_______ | | > | | | > |_______| |_______ > > I've tried to generilze it, but I get no reduction of the number of > vertices. I can't figure out why! > > v.generalize input=grd0_MASKED output=grd0_MASKED_Gen type=area > method=douglas_reduction threshold=50 reduction=50 > > Any advice?
v.buffer has some problems, http://trac.osgeo.org/grass/ticket/90 It's not a perfect solution but maybe try v.to.rast + r.buffer + r.to.vect ? Hamish ____________________________________________________________________________________ Be a better friend, newshound, and know-it-all with Yahoo! Mobile. Try it now. http://mobile.yahoo.com/;_ylt=Ahu06i62sR8HDtDypao8Wcj9tAcJ _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
