[GRASSLIST:3176] Re: Proper input for r.sunmask (GRASS5.3)

[Markus Neteler]

On Wed, Apr 14, 2004 at 03:53:31PM +0200, Javier A. Yebrin wrote:
> Hi all!
> I'm trying to use r.sunmask in order to calculate shadowed areas. My DEM's
> resolution is 5x5 meters and it has an extension of 4x4 km.
> r.sunmask appears to hang at 0% when calculating shadows for DEM(after
> having succesfully calculated sun position). Should i be more patient? or is
> it something wrong?

r.sunmask is just extremely slow.

A trick: use r.sun instead:

 http://grass.itc.it/gdp/html_grass5/html/r.sun.html
 - use -s flag
 - "A map of shadows can be extracted from the solar incidence 
    angle map (incidout). Areas with zero values are shadowed."

Hope this helps,

 Markus