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

[Markus Neteler]

Joshua,

On Mon, Nov 30, 2009 at 5:50 PM, Joshua Campbell
<jcampbell.geo at gmail.com> wrote:
> 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.

ok.

> 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 suspect that you have hit the 2GB limit but...

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

... if it is *really* a 64 bit binary that should not matter.
If 32bit, then there is the --enable-largefile flag to configure
the GRASS source code before compilation.

> 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)

Sounds good :) Unfortunately I have no time...

best
Markus