if you have start and end point of geom B, you can get the river path with a shortest path method (one liner using python, can be done in few hours using plpgsql).
The idea is that you cut your geom into segments(pairs of points) , the length of the segment is the weight of this edge , and you know which segment is connected to which segment (adjacency graph). Then you use Networkx <http://networkx.lanl.gov/reference/generated/networkx.algorithms.shortest_paths.generic.shortest_path.html#networkx.algorithms.shortest_paths.generic.shortest_path>shortest path distance. Else, you are up to use some nasty workaround I suppose (playing with buffers on your original river surface, testing which segment intersects etc. ). I tried that but it ends up being more work (and more corner cases) than doing the things properly (in my experience). Cheers, Rémi-C 2015-06-08 16:42 GMT+02:00 toni hernández <t...@sigte.udg.edu>: > Hi everyone, > > I have a multilinestring with a river and all its afluents as you can see > in this image > http://sigserver4.udg.edu/apps/geometries.png > > I got geometry A using St_StraithSkeleton. > > Is there a way to go from geometry A to geometry B?? > Maybe something similar to SmoothLine??? > > > -- > *Toni Hernández Vallès* > Servei de Sistemes d'Informació Geogràfica i Teledetecció > - > Universitat de Girona > *SIGTE* > - > Pl. Ferrater Mora 1 > 17071 Girona > Tel +34 972 418 039 (7026 intern) > t...@sigte.udg.edu > > http://www.sigte.udg.edu > Twitter http://twitter.com/SIGTE_UDG > > > _______________________________________________ > postgis-users mailing list > postgis-users@lists.osgeo.org > http://lists.osgeo.org/cgi-bin/mailman/listinfo/postgis-users >
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