[GRASSLIST:1992] Re: Aspect and Shaded relief

[Patrick Dunlavey]

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