[GRASS-dev] How to sample raster values along a vector line?

[Helmut Kudrnovsky]

Markus Neteler wrote
> Hi devs,
> 
> I somehow don't get how to sample values from a raster map along a
> vector line which is several pixels long.
> In essence, something like this
> #1852: r.profile: accept lines vector map as profile
> https://trac.osgeo.org/grass/ticket/1852
> 
> Issues:
> - I tried v.split but don't know how to extract the nodes from the
> resulting map.
> - I also tried v.to.points but the distance is "random". Try this:
> 
> # NC data
> v.to.points railroads output=railroads_nodes use=node dmax=200
> 
> g.region vector=railroads_nodes
> d.mon wx0
> d.vect railroads_nodes
> --> ??
> 
> I found a hint about v.drape but also no success.
> 
> Any suggestions?
> 
> thanks
> Markus
> 
> PS: I have roughly 100.000 lines to process.
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a very simple implementation for just 1 vector line to get sample points
along a river/transect/whatever with a fixed segment length:

https://grass.osgeo.org/grass70/manuals/addons/v.fixed.segmentpoints.html

maybe it could be extended to loop through all lines of a vector?



-----
best regards
Helmut
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