Dave Roberts wrote: > Friends, > > If I understand correctly (based on experience with my own data), when > GRASS calculates the topology for vector area data it doesn't actually > ensure that the centroid lies within the area it represents. If the area is > a torus, or at least hollow in a general way, then the centroid might > actually lie in the void in the center of the polygon rather than within the > interior of the polygon itself.
No, grass does ensure that a centroid lies within an area when building topology (attaching centroids). After building full topology, the number of centroids outside any area is reported as Number of centroids outside area: Markus M _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user