Hi, as your points are intersections along the river course you could create a network within GRASS (v.net with points as nodes). I think then it should be possible to use a tool like v.net.distance to calculate distances between the nodes which is basically the basis for any ordering along the line. Unfortunately, I haven't performed such analysis myself, so I can't provide any example, but the manuals of the v.net.* tools should be helpful in this case.
cheers, Johannes On Mon, Nov 18, 2013 at 7:39 PM, Carlos Grohmann <[email protected]>wrote: > Hi there > > I've been looking into this, but not sure about the best way to do it: > > I have a set of points that lie over a line (the line is a river course > and points are intersections with contour lines). I want to order the > points 'downstream', so I can make a long profile of the river (just > sampling elevations from a DEM at line nodes gives too much noise, some > papers suggest contours intersections work better). > > Question is: how? After some searching I found the Network Analysis of > QGIS, but still not sure if that's the best approach. The river is very > meandering, so nearest neighbour won't work because the nearest node might > not be the next one downstream > > I'm open to suggestions > > thanks > > Carlos > > > > > -- > Prof. Carlos Henrique Grohmann > Institute of Geosciences - Univ. of São Paulo, Brazil > - Digital Terrain Analysis | GIS | Remote Sensing - > > http://carlosgrohmann.com > http://orcid.org/0000-0001-5073-5572 > ________________ > Can’t stop the signal. > > _______________________________________________ > grass-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/grass-user >
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