[GRASS-user] r.sun and XY locations

[Hamish]

Christian wrote:
> I thought that is why I can provide latitude and longitude grids as
> input for the very special case of an XY location. Isn't it like that?

Hi,

r.sun was originally written with that idea in mind -to be able to run
from a non-projected simple XY coordinate system- if you fed it raster
maps containing the lats and lons and told it where the sun was in the sky.

But the generation of the program currently in GRASS 6 has moved away
from that, and now requires to be run from a lat/lon or projected location.
Actually in GRASS 7 that need is eased as we got rid of the inner loop
projection code so that the OpenCL GPU enhanced version of r.sun could
be used. But at the same time I've slowly been having it make more and more
assumptions that a way to get lat/lon would exist-- I didn't think someone
had tried to use it with a XY location in many many years and was getting
ready to remove that completely to simplify the module. I guess I was
wrong about the demand for it, but regardless of that is there any reason
that the pyWPS wants to or needs to use a XY location instead of a
projected or geographic one? I assume the pyWPS has some sort of spatial
knowledge to it, and setting a few lines of text in the PROJ_INFO file
is probably a lot simpler and faster than going to the trouble of making
lat and long raster maps to feed to r.sun. The easier solution might also
be the more correct one!


regards,
Hamish