[Qgis-user] What's wrong with PRJ file for CRS 3857?

[Goyo]

See also http://spatialreference.org/ref/sr-org/7483/ where both OGC
WKT and ESRI WKT and a .prj file are provided. The OGC version is
different from the one in by eps-registry.org. The ESRI version is
used for the .prj file.


It looks like gdal can read both OGC and ESRI WKT:

"If a .prj files in old Arc/Info style or new ESRI OGC WKT style is
present, it will be read and used to associate a projection with
features."
http://www.gdal.org/drv_shapefile.html

But everybody seems to be using ESRI version for .prj files, for
compatibility I guess.


See also some interesting comments about the differences between both
formats, some of them by ESRI people:
http://gis.funmontage.com/questions/129764/how-are-esri-wkt-projections-different-from-ogc-wkt-projections

Goyo

2015-09-21 12:59 GMT+02:00 Redoute <redoute at tortenboxer.de>:
> Am 16.09.2015 um 15:43 schrieb Redoute:
>
>> I hope with your help we can describe the error more
>> precisely to make an informed bug report.
>
> Not sure about this yet. In GDAL I found the function OSRMorphToESRI()
> (<https://svn.osgeo.org/gdal/sandbox/libosr/ogr/ogr_srs_esri.cpp>).
>
> I think QGIS stores the result of this function in the prj file. This
> would be OK as long as the operation is reversible. Is it necessary?
> Does current ArcGIS refuses to read WKT with Auth-IDs? Will "morphing"
> still be necessary when GDAL and ArcGIS implement the new WKT standard
> (when?)? This would have to be considered by QGIS.
>
> If this should stay as it is, QGIS could handle 3857 as a special case
> and dont "morph" it's WKT, as the morphed one is known as unusable.
>
> Probably OSRMorphToESRI() should write
> PROJECTION["Mercator_Auxiliary_Sphere"] for EPSG:3857, and implement
> this method. This would have to be changed by GDAL. I think it is the
> same method as EPSG 1024: "Popular Visualisation Pseudo Mercator". Again
> this may be related with the new WKT standard.
>
> Or would MetaCRS (https://trac.osgeo.org/metacrs/) be the right place to
> report this?
>
> Redoute
>
>
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