[GRASS5] searching for cast shadow algorithm (r.sunmask?)

[Markus Neteler]

Hi all,

many thanks for your recommendations on my shadow problem.

Good news: Huidae got the r.sunmask working (it's pretty slow
with FP maps, but working)!

You can test the current CVS version with a simple block in the landscape:

r.mapcalc test="if((row() > 100 && row() < 150 && col() > 100 && col() < 150),20,0)"
r.sunmask -z elev=test output=shadow alt=10  azim=45
d.rast shadow

Huidae, I have recoded the output values to:
 no shadow: null()
 shadow: 1

Is that o.k. with you?


On Mon, Mar 05, 2001 at 02:13:22PM +0700, Justin Hickey wrote:
[...]
> For a shading algorithm you can check the following paper:
> 
> Fast Hill Shading with Specular Reflection and Cast Shadows - by C Ware
> "Computers and Geosciences" 1989, 15, pages 1327-1334
> 
> I used an in-house library based on this algorithm for my Masters thesis
> and it seemed to work well.

Other suggestions are the "-s" flag of r.sun or to modify a line of sight
algorithm.

Thanks for all your help,

 Markus

---------------------------------------- 
If you want to unsubscribe from GRASS Development Team mailing list write to:
minordomo at geog.uni-hannover.de with
subject 'unsubscribe grass5'