Thank you for your help,
i'll try r.stream.extract
I do have set a small threshold value but it is on purpose.
The streams i am trying to model are not hydrological.
Best regards,
Adrien
Le 19-03-31 à 09 h 48, Markus Metz a écrit :
On Sat, Mar 30, 2019 at 5:30 PM Micha Silver <[email protected]
<mailto:[email protected]>> wrote:
>
>
> On 29/03/2019 22:03, Adrien André wrote:
>
> Hello,
>
> following the wiki doc about stream extraction [1], once the stream
layer thinned and vectorized,
> there are many small arcs i would like to remove (see attached
capture [2]).
>
> So, with the underlying drainage direction map [3], and the
resolution r, i would like to delete segments
> - about r*sqrt(2) long
> - whose azimuth is more than 45° different from the pixel value
under its starting point.
>
>
> This might be possible, but I think the best approach would be to
choose the correct threshold value for r.watershed from the start.
>
> Trying to manually "fiddle" with the stream network will most likely
leave you with disconnected segments, or other inconsistencies.
+1
Please try r.stream.extract in order to get a clean vector stream
network. The approach r.thin + r.to.vect creates noise and does not
always follow flow directions.
Markus M
>
>
> But i still haven't figured a way to achieve this.
>
> Do you have any advice ?
>
> Thank you,
>
> Best regards,
>
> [1]
https://grasswiki.osgeo.org/wiki/Creating_watersheds#Display_first_results
> [2] https://framapic.org/1exdxrdqxemw/ytuVxiBp2FKh.png
> [3] https://grass.osgeo.org/grass74/manuals/r.watershed.html
>
>
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>
> --
> Micha Silver
> Ben Gurion Univ.
> Sde Boker, Remote Sensing Lab
> cell: +972-523-665918
>
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--
Adrien
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