Thanks all. i think that the current solution is good enough. maybe next time i'll try the 6.5 with feature.
thanks On Thu, May 28, 2009 at 10:39, Moritz Lennert <[email protected]>wrote: > On 25/05/09 18:00, Stefano wrote: > >> Hi all. >> i'm looking to v.select (grass 6.4). >> >> i've 2 paths done by v.net.path, i want to extract the diff path of >> these 2 paths using v.select, overlap and the reverse. >> before this operation i clean both of them using break and snap. >> >> As you can see in the image there are two path, one blue and one >> green, these two path sheared pieces (u can't see the shared path,but >> is not imporant). >> so, i want find the differences of these two path. >> i do the select with a reverse command but the result is not right as >> i can excepted. >> >> if u pay attention the black path (the diff path) is not completly >> right. in fact this path has to start and finish on the intersection >> of these two path (blue and green) but start and end before the >> intersection. so the black path has to be identical as the green path >> (the green path that u can see) >> >> i think the problem is the lines of these 2 path (green and blue) that >> are not cut in the intersection, so the line goes across the >> intersection of these line. >> >> how can i fix this problem? >> > > v.select does not cut exactly at the edges of overlap, but selects the > entire feature that overlaps, even if this feature goes beyond the overlap > (i.e. it does an "overlap" and not an "intersect"). > > What you want is v.overlay, but unfortunately this has never been > implemented for two line layers (never understood why). > > Your best solution at this stage is to compile the current grass6 svn tree > (6.5) with the --with-geos configure flag which will give you access to a > much more wide array of tools than only overlap [1]. > > Moritz > > [1] http://grass.osgeo.org/grass65/manuals/html65_user/v.select.html > -- Stefano
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