[GRASS-user] long run time with r.sunmask

[Hamish]

Markus Neteler wrote:
> Dylan Beaudette wrote on 03/08/2007 02:25 AM:
> > Hi everyone,
> >
> > using the latest CVS, I noticed that running r.sunmaks on a
> > relatively small  region (300x300 cells) took a very long time to
> > run (about 15 minutes). I am  using a DEM for the location and
> > specifying the time of day, and day of the  year. I used the
> > following command:
> >
> > r.sunmask elev=elev_meters out=shadows_afternoon timezone=-8
> > year=2007 month=3  day=31 hour=16 minute=00 second=00
> >
> > Any idea on why this would take so long?
> >   
> ... because of r.sunmask slowliness...
> For a fast solution, use r.sun instead.
>   Shadow maps
>        A  map  of  shadows can be extracted from the solar incidence
> angle map (incidout). Areas with
>        zero values are shadowed. The -s flag has to be used.


any idea if this is because of the (better) SOLPOS algorithm r.sunmask
uses, or is it just inefficient structure in the r.sunmask module?

ie if/when r.sun is updated to use SOLPOS, can we expect a big slowdown
in r.sun run times?


Hamish