[GRASS5] [bug #2533] (grass) r.sunmask

[Markus Neteler]

On Wed, Jul 14, 2004 at 10:46:42AM +0200, Request Tracker wrote:
> this bug's URL: http://intevation.de/rt/webrt?serial_num=2533
> -------------------------------------------------------------------------
> 
> Subject: r.sunmask
> 
> Platform: GNU/Linux/i386
> grass obtained from: Trento Italy site
> grass binary for platform: Compiled from Sources
> GRASS Version: GRASS 5.7.0 (2004)
> 
> for my DEM (2800 by 2800) it takes 40 hours to calculate the cast shadow 
> with r.sunmask. 
>  
> for a hydrologic model i need the cast shadow for one year, time step one 
> hour. 
>  
> is it possible to speed up the r.sunmask?

Maybe, this needs a voluteer.

> or is it even possible to 
> calculate only for a mask which covers only one third of the DEM? 
>  
> thank you, sabine 


You can simply use 'r.sun' instead of r.sunmask. It's much
faster.

Use the -s flag and see it's manual page:
"A map of shadows can be extracted from the solar incidence angle map (incidout).
 Areas with zero values are shadowed."


Markus