Dwight Needels wrote: > > When the rmdangle tool runs into a pair of dangles at the end of a > line where each is shorter than threshold (a "Y"), it removes one but > leaves the other. This makes sense, because after the first one is > removed the second one is no longer a dangle (it is now the terminal > line segment). "Line segment" is confusing because it refers to a part of a line, e.g. a part of line C or A. Line E may have only one segment, line C is composed of several segments. > > The question is, how does it decide which one to remove ? First come fist serve. The rmdangle tool doesn't really decide, it goes through all lines and if a line is a dangle and shorter than threshold, it gets removed. The tool does not look at a pair of dangles at once as far as I can tell. > I expected rmdangle to remove the shorter of the two choices in each > instance. In my example, lines A, B, D & E are all shorter than the 30 > ft threshold, and A, D & E are dangles. Removing the shorter dangle at > each decision point would leave the longest below-threshold segments > (A & B) while removing the two shorter ones (D & E). Instead, rmdangle > leaves only the shortest segment (E) while removing the three longest > ones (A, B & D), including one that isn't a dangle in the original > vector. Looks like A and D were removed first, then B qualified as a dangle and was also removed, but why line E stayed in place is strange, it should also be removed with that threshold. > > How does v.clean tool=rmdangle decide which dangle to remove when > there is a choice between two dangles shorter than the threshold? I think first come first serve, no decision or comparison between two dangles happens. I may have to go to the source code again to make sure...
Markus M _______________________________________________ grass-user mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/grass-user
