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Here's a thought:
If you have the elevation of each of the points (from the contour
lines) then this could be used to order the points (assuming the
river never runs uphill :-) ). So it could be as easy as:
v.out.ascii,
sort the list by the elevation, then v.in lines.
On 18/11/2013 20:39, Carlos Grohmann 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 -
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Micha Silver
GIS Consulting
052-3665918
http://www.surfaces.co.il
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