[GRASS-user] v.to.rast, r.to.vect, "stable" transformation

[Moritz Lennert]

On 26/01/12 10:29, Johannes Radinger wrote:
> Hello,
>
> as it seems that there was something wrong with my post yesterday I send it
> again (if everything was ok already yesterday, sorry for double posting):
>
>
> For a certain application I need to transform a river from the
> raster format into the vector format and vice versa.
>
> I'd like to know how good does it work to tranform a line
> feature from vector into raster and back again into
> a vector? Is there any "stable" line which doesn't
> change anymore after x-times transforming back and
> forwards? I haven't had time to test it but I thought about:
>
> v.to.rast
> r.thin
> r.to.vect
>
> this should result in a "stable" line or does it
> need several iterations?

I think the best way is to try, but some remarks here:

- I don't think that r.thin avec v.to.rast will change anything. 
v.to.rast should already limit the raster version of the line to a 
widthof one pixel.

- The main issue here will probably be the resolution.

- To test, just try running v.to.rast/r.to.vect several times in a loop 
and then compare the end result to the original river...

Moritz