[GRASS-user] r.horizon problems with large DEM

[Joshua Campbell]

Markus,

Thanks for the input. I reviewed the r.sun page and unfortunately r.sun
doesn't provide the specific horizon angle provided by r.horizon. My goal is
not to compute solar irradiance.

I was able to run r.horizon on a subset that was ~4900x9900. The DEM I'm
trying to use in 30000x78000 (but is has quite a bit of null values).

Do you know if there is pixel dimension limit to r.horizon?

I am using the 64-bit package available through the Ubuntu site -- would it
make a difference if I built the code from source?

Do anyone know of a script that would iteratively set a region, compute
r.horizon (with a buffer), move the region, and r.patch the resulting
horizon files?
If anyone is interested in writing this script, we could discuss
compensation (contact directly at jcampbell.geo at gmail.com)

Thanks,
Josh

Joshua Campbell
Kansas Applied Remote Sensing Program
University of Kansas
Lawrence, KS

On Sun, Nov 29, 2009 at 3:13 PM, Markus Neteler <neteler at osgeo.org> wrote:

> On Mon, Nov 23, 2009 at 8:05 PM, Joshua Campbell
> <jcampbell.geo at gmail.com> wrote:
> > I have been trying to run r.horizon on a SRTM DEM for the continental US,
> > with no success. The operation runs for about 45 minutes then eventually
> > just stops with no warnings or errors
> >
> > I'm running GRASS 6.4-rc5 64-bit in Ubuntu 9.10 on a virtual machine
> > (Virtual Box on Windows XP 64-bit).
> >
> > The r.horizon function will consume as much RAM as apply to the machine,
> up
> > to 6144 MB, plus an additional 4GB of swap memory.
> >
> > The DEM is in Geographic coordinates - WGS 84. I tried to run r.horizon
> in
> > only 1 direction with maximum distance of 5310 meters.
> >
> > Is there a file size limitation? Or any suggestions for an optimal size?
>
> Do you really want r.horizon or do you want it as input for r.sun?
> If so, see also here:
> http://grass.osgeo.org/wiki/Rsun
>
> I recently used r.sun without r.horizon and it took way less RAM.
>
> Markus
>
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