[GRASS-user] ordering points along a line

[Johannes Radinger]

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
<carlos.grohmann at gmail.com>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.
>
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