[GRASS-user] Re: [GRASS-dev] d.barb: call for testing

[Dylan Beaudette]

On Wednesday, April 27, 2011, Hamish wrote:
> Dylan wrote:
> > Nice work! 
> 
> cheers
>  
> > I had been thinking about using this type of graphic to
> > describe the potential movement of water/sediment flux along
> > landscape gradients for some time now... 
> > With a little bit of tinkering around, I was able to get a
> > figure that matched> my mental picture:
> > 
> > http://basho.dyndns.org/~dylan/temp/d.barb_terrain_example.jpg
> > 
> > Colors represent mean curvature, contours are every 10
> > meters, white lines are from r.flow, arrow direction is from
> > an aspect map, arrow length is scaled by the compound
> > topographic index.
> 
> for the record, d.rast.arrow has been able to do this for some
> time now, see the GRASS raster screenshots page for an example.
> (actually for the d.barb Eulerian array fields I just adapted
> my earlier scaled arrow code from there)
> 
> 
> a tip to get rid of the outer cell-border of garbage values:
> r.mapcalc "invert = if(isnull(map), 1, null()"
> r.grow in=invert out=invert_buf1
> r.mapcalc "MASK = if(isnull(invert_buf1), 1, null()"
> r.mapcalc "crop = map"
> 
> 
> Hamish
> 
> 

Thanks for the tips, that worked well.

Dylan


-- 
Dylan E. Beaudette
USDA-NRCS Soil Scientist
California Soil Resource Lab
http://casoilresource.lawr.ucdavis.edu/