[GRASS-user] r.slope.aspect shifts longitude on global maps

[A. Marcia BARBOSA]

Hi,

I'm trying to create a slope map using r.slope.aspect on a global DEM
imported from Worldclim. The map is generated and the slopes look
correct, but the E-W coordinates are displaced – DEM is between 180
and -180 degrees, Slope comes out between 540 and 180! So the maps
show up side by side instead of one on top of the other. Is this
normal?

If I do it on smaller regions within the DEM it works OK, except if
the E-W coordinates of the region go from 180 to -180. So I figured I
can get my (almost) global slope map if I temporarily set the region
to 90 N, -90 S, 179.9 E and -179.9 W (instead of 180 and -180). This
seems to work, but I'm left with a thin vertical stripe without any
slope values around the 180 degrees longitude, which is not really
ideal.

Cheers
Márcia