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

Moritz Lennert mlennert at club.worldonline.be
Thu Jul 9 12:13:28 EST 2009

On 07/07/09 18:55, Frank Warmerdam wrote:
> 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 ?
> Moritz,
> File a PROJ.4 ticket and I'll look into it. 



> 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.

Not really both the bel72 -> wgs84 and bel72 -> etrs89 use the same 


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