[gdal-dev] Confused about datum transformations

[Chaitanya kumar CH]

Marc,

Looks like there might be a problem with the targetSRS. Please check if it
is ok. Try the exportToWkt method on it. Also, make sure the file pcs.csv in
gdal's data directory contains the entry for 3577.

On Tue, Oct 18, 2011 at 3:41 PM, <dev4cx4m9z at snkmail.com> wrote:

> I’m not sure the code will help too much, but here are the relevant code
> fragments. I’m using a hand crafted VB.net wrapper which explains some of
> the syntax****
>
> ** **
>
> Private WGS84SRS As New OGRSpatialReference     ' Coordinate system in
> WGS84****
>
> Private MapSRS As OGRSpatialReference       ' Coordinate system of map****
>
> Private ctWGS84toMap As OGRCoordinateTransformation       ' Coordinate
> transform from WGS84 to map****
>
> ** **
>
> With WGS84SRS****
>
>     GDALError = .SetProjCS("WGS84 Datum")****
>
>     Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())****
>
>     GDALError = .SetWellKnownGeogCS("WGS84")          ' Define WGS84
> coordinate system****
>
>     Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())****
>
> End With****
>
> ** **
>
> With MapSRS****
>
>      GDALError = .SetProjCS("Map coordinate system")****
>
>      Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())****
>
>      GDALError = .ImportFromEPSG(3577)****
>
>      Debug.Assert(GDALError = OGRError.OGRERR_NONE, GetLastErrorMsg())****
>
> End With****
>
> ** **
>
> ctWGS84toMap = GDAL.CreateCoordinateTransformation(WGS84SRS, MapSRS)
> ' Create a coordinate transformation - WGS84 to map****
>
> Debug.Assert(ctWGS84toMap IsNot Nothing, GetLastErrorMsg())****
>
> ** **
>
> Marc,
>
> Can you provide the code leading to the error?****
>
> On Tue, Oct 18, 2011 at 1:21 PM, Marc Hillman <dev4cx4m9z at snkmail.com>
> wrote:****
>
> I have a GIS database, and all data is stored in WGS84 datum. I have
> developed an application using GDAL, and I now need to translate my WGS84
> coordinates to several different datums, depending what map is loaded. I
> seem to be going around in circles, and need a nudge in the right direction.
> I am defining an OGRSpatialReference for each datum (WGS84 and current map)
> and then attempting to create an OGRCoordinateTransformation for the
> transformation.. This last step fails with a PROJ.4 error (“No PROJ.4
> translation for destination SRS, coordinate transformation initialization
> failed”****
>
>  ****
>
> My question is - Do I need PROJ.4 to do the translation? Can I not just use
> ImportFromWKT to define my OGRSpatialReference? If so, is there a nice
> canned list of all the WKT somewhere?  I’m keen to avoid PROJ.4 if possible
> as I’m not sure I can build it.****
>
>  ****
>
>
> _______________________________________________
> gdal-dev mailing list
> gdal-dev at lists.osgeo.org
> http://lists.osgeo.org/mailman/listinfo/gdal-dev****
>
>
>
>
> --
> Best regards,
> Chaitanya kumar CH.
>
> +91-9494447584
> 17.2416N 80.1426E
>
> ****
>
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-- 
Best regards,
Chaitanya kumar CH.

+91-9494447584
17.2416N 80.1426E
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