[Gdal-dev] Oblique_ vs Double_Stereographic

[Maciej Sieczka]

Frank

GIS data created in ESRI software, projected in EPSG 3120,2172-2174,
have their PROJECTION specified as Double_Stereographic (eg. [1]).
However, GDAL and dependent software use
PROJECTION["Oblique_Stereographic"] for these systems. This leads to
mismatches during data exchange, eg. v.in.ogr claims the shapefile
projected in 2174, created with ESRI software, does not match a GRASS
location set up using the same code - due to unknown projection name
Double_Stereographic [2].

I don't know for other 13 sterea projections [3], but according to [4]
ESRI's Double_Stereographic is the same as GDAL's
Oblique_Steregraphic, and that seems to make sense for 3120,2171-2174.

Should Double_Stereographic be intepreted as Oblique_Steregraphic by
GDAL and friends?

Please read Paul Kelly's comments on grass-dev:
http://www.nabble.com/Re%3A--GRASS-user--problem-with-vi.in.ogr-tf2934543.html

The discussion started on grass-user:
http://www.nabble.com/problem-with-vi.in.ogr-tf2931526.html

[1]
Layer SRS WKT:
PROJCS["PUWG_65_Strefa_IV",
    GEOGCS["GCS_Pulkovo_1942",
        DATUM["Pulkovo_1942",
            SPHEROID["Krasovsky_1940",6378245.0,298.3]],
        PRIMEM["Greenwich",0.0],
        UNIT["Degree",0.0174532925199433]],
    PROJECTION["Double_Stereographic"],
    PARAMETER["False_Easting",3703000.0],
    PARAMETER["False_Northing",5627000.0],
    PARAMETER["Central_Meridian",16.67222222222222],
    PARAMETER["Scale_Factor",0.9998],
    PARAMETER["Latitude_Of_Origin",51.67083333333333],
    UNIT["Meter",1.0]]

[2]
No projection name! Projection parameters likely to be meaningless.
A datum name S-42 (Pulkovo_1942) was specified without transformation
parameters.

[3]
$ grep -c "proj=sterea " /usr/local/share/proj/epsg
18
(substract 4 deprecated of them)

[4]
http://udig.refractions.net/docs/api-geotools/org/geotools/ct/proj/Stereographic.html