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

[Hamish]

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