[GRASS-user] Vector from Raster Problems (r.stream)

Jarek Jasiewicz 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.  

> Is
> 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.
> thanks,
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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