[Proj] trying to understand results of reprojecting from epsg 4326 to epsg 31370

Frank Warmerdam warmerdam at pobox.com
Tue Jul 7 11:55:31 EST 2009

Moritz Lennert wrote:
> On 07/07/09 16:56, Noel Zinn wrote:
>> Consider changing the signs of the three rotations if you can do that 
>> manually, or the rotation sense of the 7-parameter transformation.
> That was it. Thanks also to Clifford for the same hint. Could someone 
> explain the logic to me ? Why negate the translation, but not the 
> rotation compared to the WGS84->Bel72 transformation ?
> And: should the information linked to EPSG code 31370 be corrected ? How 
> should I go about doing this ?


File a PROJ.4 ticket and I'll look into it. I need to establish if the
problem is a systematic one in how I translate the parameter from EPSG,
or if it is an incorrect local override or if there is a problem in the
EPSG database itself.  I suspect there are two "towgs84" forumulations
in the EPSG database with different handedness and I'm not properly
differentiating them.

Best regards,
I set the clouds in motion - turn up   | Frank Warmerdam, warmerdam at pobox.com
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | Geospatial Programmer for Rent

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