[GRASSLIST:1996] Re: Aspect and Shaded relief

[Markus Neteler]

On Wed, Jun 20, 2001 at 08:57:20AM -0400, Patrick Dunlavey wrote:
> At 01:28 PM 6/20/01 +0200, Karin(e) ZUERCHER wrote:
> >Hello everybody!
> >
> >With Arcview and some others, it is possible to make a nice picture of the
> >relief called 'sheade relief' or something, where you can choose the
> >orientation and hight of the light source (sun). There is also something
> >called aspect map, but it only gives a result of slope orientation without
> >accounting for inclination (thus you get a look of V shaped valleys instaed
> >of U shaped, fo rinstance).
> >
> >I know about and until now used grass ASPECT map to get more or less a
> >shaded relief.  I didn't find any module that seams to allow making shaded
> >reliefs like in arcview or so.
> >
> >I am wondering, did I miss something or deos it not exist in grass yet?
> >I that's the case, I guess it should be possible to compute something with
> >slope and aspect map, and wonder if someone has an idea how that is done
> >(what algorithms or whatever needed)?
> >
> >Thanx in advance for your help
> >In Kindness
> >Karine
> 
> There is a script called shade.rel.sh in your grass5/scripts directory, 
> which uses r.mapcalc. It works pretty well, at least when your x, y and z 
> coordinates are all in the same units. There's also shade.color.sh, which I 
> haven't played with.
> 
> -- Pat

Hi,

you may also use d.his and "overlay" the map (DEM or whatever) to
the aspect map. See the related tcltkgrass entry "shaded relief" as
well.

Hope this helps,

 Markus