[gdal-dev] different results for vector and raster data reprojections

[nimalika fernando]

Hi,

I have used ogr2ogr to assign projection information(SL99) to some vector
data which does not contain any projection information.

I used the same projection information to reproject a raster in UTM 44N to
SL99.Both data sets contain data of same location.



When I try to overlay the projected data  ( using QGIS where the SL99 is
defined using the same projection information) there is a small shift in two
layers.



When check the projection information using ogrinfo/gdalinfo I found that
even though the same parameters are used for projection of vector and raster
data , some parts of the WKT is different. I am not sure whether this is the
reason for the problem in overlapping.



The resulting WKT are as follows

Raster



PROJCS["Transverse_Mercator",

    GEOGCS["Everest 1830",

        DATUM["unknown",

            SPHEROID["unnamed",6377276.345,300.8017000000115]],

        PRIMEM["Greenwich",0],

        UNIT["degree",0.0174532925199433]],

    PROJECTION["Transverse_Mercator"],

    PARAMETER["latitude_of_origin",7.00047],

    PARAMETER["central_meridian",80.77171],

    PARAMETER["scale_factor",1],

    PARAMETER["false_easting",200000],

    PARAMETER["false_northing",200000],

    UNIT["metre",1,

        AUTHORITY["EPSG","9001"]]]



Vector

PROJCS["Transverse_Mercator",

    GEOGCS["Everest 1830",

        DATUM["unknown",

            SPHEROID["evrst30",6377276.345,300.8017]],

        PRIMEM["Greenwich",0],

        UNIT["Degree",0.017453292519943295]],

    PROJECTION["Transverse_Mercator"],

    PARAMETER["latitude_of_origin",7.00047],

    PARAMETER["central_meridian",80.77171],

    PARAMETER["scale_factor",1],

    PARAMETER["false_easting",200000],

    PARAMETER["false_northing",200000],

    UNIT["Meter",1]]



Can anybody help me to identify what went wrong  ?

Thanking you



nimalika
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.osgeo.org/pipermail/gdal-dev/attachments/20090228/00441567/attachment.html