[GRASS-user] Problem re-projecting 'WGS_1984_Web_Mercator_Auxiliary_Sphere'

[Moritz Lennert]

On 08/09/16 17:10, Stuart Edwards wrote:
> Hi -
>
> I'm trying to work with some vector data that is in the 'WGS_1984_Web_Mercator_Auxiliary_Sphere' projection - an apparently popular web mapping projection.  I want to re-project it to a state plane co-ordinate system (ohio-north us survey ft).
>
> The EPSG code for the raw data is (reportedly) 3857, but GRASS gives the following error messages when trying to import to a location set to this projection:
>
> 'Projection of following layers do not match with projection of current location' ....... the layers will be re-projected.
>
> This fails and the console shows the following error:  ERROR 6:  No translation for Mercator Auxiliary Sphere to PROJ.4 format is known.
>
> The data import to an x,y location with an ERROR 6 message, but otherwise seems intact including attributes (just crazy co-ordinates).
>
> Re-projecting to the SPC location fails with:  v.proj --overwrite location=OHxy mapset=PERMANENT input=PCR_Local output=ohPCR       	WARNING: <PROJ INFO> file not found for location <OHxy>
>
> With some minor aggravation my wife's arcgis was able to figure this out - but any suggestions on how to proceed in GRASS would be much appreciated.
>

This is a very difficult projection system to deal with, to the point 
that many agencies have banned it.

Please see https://trac.osgeo.org/grass/ticket/2229 for a discussion on 
that issue.

Moritz