Opened 10 years ago

Closed 10 years ago

#3032 closed defect (fixed)

Hotine Oblique Mercator translation to PROJ.4 format looses scale factor.

Reported by: warmerdam Owned by: warmerdam
Priority: normal Milestone: 1.6.2
Component: OGR_SRS Version: unspecified
Severity: normal Keywords: somerc hotine oblique mercator HOM
Cc: vjetly

Description

A HOM coordinate system like:

PROJCS["HD72 / EOV",
    GEOGCS["HD72",
        DATUM["Hungarian_Datum_1972",
            SPHEROID["GRS 1967",6378160,298.247167427,
                AUTHORITY["EPSG","7036"]],
            AUTHORITY["EPSG","6237"]],
        PRIMEM["Greenwich",0,
            AUTHORITY["EPSG","8901"]],
        UNIT["degree",0.01745329251994328,
            AUTHORITY["EPSG","9122"]],
        AUTHORITY["EPSG","4237"]],
    UNIT["metre",1,
        AUTHORITY["EPSG","9001"]],
    PROJECTION["Hotine_Oblique_Mercator"],
    PARAMETER["latitude_of_center",47.14439372222222],
    PARAMETER["longitude_of_center",19.04857177777778],
    PARAMETER["azimuth",90],
    PARAMETER["rectified_grid_angle",90],
    PARAMETER["scale_factor",0.99993],
    PARAMETER["false_easting",650000],
    PARAMETER["false_northing",200000],
    AUTHORITY["EPSG","23700"],
    AXIS["Y",EAST],
    AXIS["X",NORTH]]

translates to PROJ.4 by OGRSpatialReference as:

+proj=somerc +lat_0=47.14439372222222 +lon_0=19.04857177777778 +x_0=650000 +y_0=200000 +ellps=GRS67 +units=m +no_defs

which has lost the scale factor.

Change History (1)

comment:1 Changed 10 years ago by warmerdam

Resolution: fixed
Status: newclosed

I have corrected this, adding +k_0 parameter, in trunk (r17260) and 1.6 branch (r17261). I also added a test for this in trunk (r17262). I did not attempt to port into 1.6-esri branch since it doesn't really use proj.4 format.

I am also regenerating the proj.4 'epsg' init file.

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