[GRASS-user] Vector from Raster Problems (r.stream)
jarekj at amu.edu.pl
Tue Jul 28 02:04:19 EDT 2009
stephen sefick pisze:
> I have compiled and used Jarek's stream order script and the results
> look to be satisfactory- good job!.
You use windows as I remember, isn't it It is very important for me if
program also work on windows. Please send me aslo feeback about time of
analysis and size of maps
> I am having a hard time creating
> vectors from this raster representation. r.thin -> r.to.vect creates
> lots of erroneous squares that I believe are there as an artifact of
> the larger stream networks.
It is problem that no streams are marked as 0 (for now, it will be fixed
to null). For now try to
convert 0 to null with mapcalc formula:
neworder=if(order=0,null(),order) and try again.
> The lower order (smaller) streams look
> fine, but when you start getting to the higher order streams +5 I
> think the r.thin algorithm may have problems delineating a stream.
> there a way around this? I would be happy with a line that ran
> through the middle of the stream for now. Some trick converting to
> points and then to lines? Or something along those lines. Is there a
> way to connect centroids? I have made an area map of the streams
> raster- can I connect the areas together? Thanks for any help.
I just work on another module which will be convert stream netowork to
correct vector stream network (in most cases r.to.vect do not it well)
i thing it is metter of next week.
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