[GRASS-user] Datum not recognized by Grass

[Markus Metz]

On Wed, Dec 4, 2019 at 12:23 PM Zoltan Szecsei <zoltans at geograph.co.za>
wrote:
>
> Hi Helmut,
> Thanks for your comments.
>
> I installed everything with OSGeo4W64, and QGIS get the EPSG:2932 but
> Grass not.
>
> Perhaps I have a PATH or some other setting problem?
> Perhaps let me know what search paths Grass uses for proj4, and what
> proj files and locations I should scan for.

In this case where the EPSG code is known, there is no need to do anything
but to ignore the warning. GRASS will use the EPSG code if available and
passes it to PROJ when it comes to reprojection.

Markus M

>
> Regards,
> Zoltan
>
> On 2019/12/04 01:30, Helmut Kudrnovsky wrote:
> >> ignore the warning and use GRASS with PROJ6, granted that authority
name
> > (e.g. EPSG) and authority code (e.g. 2932) are known for both CRS's in
case
> > of reprojection
> >
> > this issue is already by GRASS with PROJ6, see
> >
> > ####################
> > GRASS version: 7.8.1
> > Code revision: c865432c9
> > Build date: 2019-11-10
> > Build platform: x86_64-w64-mingw32
> > GDAL: 3.0.2
> > PROJ: 6.2.1  <=
> > GEOS: 3.8.0
> > SQLite: 3.29.0
> > Python: 3.7.0
> > wxPython: 4.0.7
> > Platform: Windows-10-10.0.18362-SP0 (OSGeo4W)
> > ####################
> >
> > and the output from the underlying PROJ: 6.2.1
> >
> > ####################
> > C:\>projinfo EPSG:2932 -o PROJ,WKT2_2018
> > PROJ.4 string:
> > +proj=tmerc +lat_0=24.45 +lon_0=51.2166666666667 +k=0.99999 +x_0=200000
> > +y_0=300000 +ellps=intl
> >
+towgs84=-119.4248,-303.65872,-11.00061,1.164298,0.174458,1.096259,3.657065
> > +units=m +no_defs +type=crs
> >
> > WKT2_2018 string:
> > PROJCRS["QND95 / Qatar National Grid",
> >      BASEGEOGCRS["QND95",
> >          DATUM["Qatar National Datum 1995",
> >              ELLIPSOID["International 1924",6378388,297,
> >                  LENGTHUNIT["metre",1]]],
> >          PRIMEM["Greenwich",0,
> >              ANGLEUNIT["degree",0.0174532925199433]],
> >          ID["EPSG",4614]],
> >      CONVERSION["Qatar National Grid",
> >          METHOD["Transverse Mercator",
> >              ID["EPSG",9807]],
> >          PARAMETER["Latitude of natural origin",24.45,
> >              ANGLEUNIT["degree",0.0174532925199433],
> >              ID["EPSG",8801]],
> >          PARAMETER["Longitude of natural origin",51.2166666666667,
> >              ANGLEUNIT["degree",0.0174532925199433],
> >              ID["EPSG",8802]],
> >          PARAMETER["Scale factor at natural origin",0.99999,
> >              SCALEUNIT["unity",1],
> >              ID["EPSG",8805]],
> >          PARAMETER["False easting",200000,
> >              LENGTHUNIT["metre",1],
> >              ID["EPSG",8806]],
> >          PARAMETER["False northing",300000,
> >              LENGTHUNIT["metre",1],
> >              ID["EPSG",8807]]],
> >      CS[Cartesian,2],
> >          AXIS["(E)",east,
> >              ORDER[1],
> >              LENGTHUNIT["metre",1]],
> >          AXIS["(N)",north,
> >              ORDER[2],
> >              LENGTHUNIT["metre",1]],
> >      USAGE[
> >          SCOPE["unknown"],
> >          AREA["Qatar - onshore"],
> >          BBOX[24.55,50.69,26.2,51.68]],
> >      ID["EPSG",2932]]
> > ####################
> >
> >> The problem is that GRASS still assumes datum transformation from X to
> > WGS84, whereas with PROJ6,
> >> WGS84 is no longer required as pivot datum. Datum transformations from
> > datum X to datum Y can
> >> sometimes (often) be done without going through WGS84. The requirement
is
> > to have EPSG or other
> >> authority codes and to use PROJ 6.
> > this warning is just from a simple v.in.ogr of a EPSG:2932-based
shapefile
> > into a EPSG:2932-created GRASS location.
> >
> > so, there may be some more adaptions needed for actions like v.in.ogr
and
> > co?
> >
> >
> >
> > -----
> > best regards
> > Helmut
> > --
> > Sent from: http://osgeo-org.1560.x6.nabble.com/Grass-Users-f3884509.html
> > _______________________________________________
> > grass-user mailing list
> > grass-user at lists.osgeo.org
> > https://lists.osgeo.org/mailman/listinfo/grass-user
>
> --
>
> =============================================
> Zoltan Szecsei GPrGISc 0031
> Geograph (Pty) Ltd.
> GIS and Photogrammetric Services
>
> P.O. Box 7, Muizenberg 7950, South Africa.
>
> Mobile: +27-83-6004028     (WhatsApp only)
> Qatar:  +974 5083 2722     www.geograph.co.za
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>
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