Moin Markus
thanks for your helpful answer. v.split is what I was looking for and
couldn't find.
I did see the v.generalize tutorial in the wiki. That's where I found
the great description of in- and circumscribing smoothing ;-) But I did
not find any information on the parameter of snakes, neither on the
manual page nor the tutorial. alpha and beta seem to influence somehow
the smoothness. But I could not figure out what the paramter threshold
does. Seems to have no effect.
Thanks
Robert
Am 19.06.19 um 18:01 schrieb Markus Metz:
Hi Robert,
On Wed, Jun 19, 2019 at 4:26 PM Robert Nuske
<[email protected] <mailto:[email protected]>> wrote:
>
> Dear Listers,
>
> I would like to smooth polygons coming from a raster via r.to.vect using
> v.generalize methods=snakes.
>
> If I understood the documentation correctly, snakes is the only method
> that tries to go the middle ground: neither entirely circumscribing
> (larger than original polygon) nor inscribing (smaller than original
> polygon) the polygon. I love that behavior. But snakes only works with
> the available vertices and does not generate new vertices => quite rough
> outlines.
>
> So i thought it would be a good idea to densify the vertices of the
> polygon before the generalization. Create new vertices with distance x
> on the boundary of the polygon. But couldn't find a function in GRASS
> doing that.
v.split -n should do exactly this: add new vertices with distance x:
length=x
The -n flag causes new vertices to be added with splitting the
lines/boundaries.
>
> I would love any hints on generalization in general and on how to
> densify my vertices.
Apart from the manual of v.generalize, there is a tutorial at
https://grasswiki.osgeo.org/wiki/V.generalize_tutorial
(maybe not completely up to date)
HTH,
Markus M
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