[GRASS-dev] Axis-orientation in GRASS GIS

[Markus Neteler]

On Wed, Dec 2, 2020 at 10:43 PM Stefan Blumentrath
<Stefan.Blumentrath at nina.no> wrote:
>
> Dear devs,
>
> One of my colleagues is working on a GRASS module for parametrized viewsheds.
>
> In that context she asked if the Y-axis in GRASS GIS (and in amongst other raster2numpy in particular) always refers to north-south direction/coordinates, even if the CRS of the location is one of the weird CRS that label north-south-direction as X-axis? Since I could not answer that question with full confidence I am forwarding it to this list.
>
> Is it safe to assume that Y always refers to North-South in  GRASS GIS?

Probably no:

to my knowledge at least the Krovak's Projection (used in Czech
Republic / Slovak Republic) is differently oriented:

http://crs.bkg.bund.de/crseu/crs/eu-description.php?crs_id=Y1NLX1MtSlRTSyslMkYrS1JPVkFL
"The axis X is the image of longitude 42°30' eastwards of Ferro
(24°50' E wrt Greenwich)
  with the positive branch oriented to the south.
  The axis Y is perpendicular to it and its positive branch is
oriented to the west."

Maybe others know more here.

Cheers
Markus