Hello,
I'm having some trouble with r.horizon. I've got a very big DEM, and I
keep running out of memory. After some experiments, I think the options
bufferzone and maxdistance may be part of the problem. It isn't listed
in the help file what the units for these are.
I'm preparing maps for use in r.sun, and the example in the r.horizon
help page suggests I use bufferzone=200 and maxdistance=2000. Does this
mean meters? units from the map projection (which are degrees)? Omitting
these parameters I can complete an analysis in a minute or so, when
including them produces a crash sometime after the process consumes all
my RAM and swap memory.
Thanks for any clarifications!
--
Tyler Smith
tyler@plantarum.ca
On 11.08.2014 22:10, Tyler Smith wrote:
Hello,
Hi Tyler,
I'm having some trouble with r.horizon. I've got a very big DEM, and I
keep running out of memory. After some experiments, I think the options
bufferzone and maxdistance may be part of the problem. It isn't listed
in the help file what the units for these are.
I'm preparing maps for use in r.sun, and the example in the r.horizon
help page suggests I use bufferzone=200 and maxdistance=2000. Does this
mean meters? units from the map projection (which are degrees)? Omitting
these parameters I can complete an analysis in a minute or so, when
including them produces a crash sometime after the process consumes all
my RAM and swap memory.
In all 6.x series as well as in GRASS ver. 7.0, the manual for r.horizon notes:
--%<---
At the moment the elevation and maximum distance must be measured in meters, even if you use geographical coordinates (longitude/latitude). If your projection is based on distance (easting and northing), these too must be in meters. The buffer parameters must be in the same units as the raster coordinates.
--->%--
Hope this helps further,
Nikos
Tyler Smith wrote:
I'm having some trouble with r.horizon. ...
I'm preparing maps for use in r.sun, ...
Also, in case you didn't read already, check-out <http://grasswiki.osgeo.org/wiki/R.sun> (and, perhaps details in this bug ticket: <https://trac.osgeo.org/grass/ticket/498> -- there might be interesting details).
Nikos
On Tue, Aug 12, 2014, at 01:48 AM, Nikos Alexandris wrote:
In all 6.x series as well as in GRASS ver. 7.0, the manual for
r.horizon notes:
--%<---
At the moment the elevation and maximum distance must be measured in
meters, even if you use geographical coordinates (longitude/latitude).
If your projection is based on distance (easting and northing), these
too must be in meters. The buffer parameters must be in the same units
as the raster coordinates.
--->%--
Thank you Nikos.
I read that passage many times, I don't know how I missed the info
hiding there in plain sight. I guess I need more sleep!
Best,
Tyler