[GRASS-dev] r.horizon -> G_set_window (maybe) error in southern hemisphere

[Hamish]

Yann Chemin wrote:
> Made a map in Australia, and wanted to use r.horizon on it.
> Nothing special, a srtm map and default conditions.
> This is the output:
> 
> (Sat Jun 20 16:51:57 2009)
> r.horizon elevin=dem25m at PERMANENT horizonstep=30 bufferzone=200
>   maxdistance=2000 horizon=horangle
> G_set_window(): Illegal latitude for North
> (Sat Jun 20 16:51:57 2009) Command finished (0 sec)

I can recreate this from a single Lat/Lon srtm file. Works fine if you
reproject it into a planimetric map projection. --->

from the man page:
"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."

i.e. for a lat/lon location bufferzone=200 makes the buffer 200 degrees
in all directions, not 200m.

otherwise, man page indicates it should work ok with lat/lon.


> rows:       52968
> cols:       39853
> cells:      2110933704

I hope you have a fast computer!


aside- perhaps the code should use G_distance() instead of its own
semi-baked distance() function??


Hamish