[postgis-users] Question on transform.
luis.mota at iscte.pt
Wed Oct 2 19:26:53 PDT 2002
Just one aditional question: what kind of transformations are known to
work correctly in PostGis? I'd like to control the transformations I
make, to avoid wrong results.
I've been trying a little bit, and the results seem very odd to me...
Thanks again, Luís
Paul Ramsey wrote:
> You can confirm on the proj4 mailing list (try this out using the
> proj4 commandline tools) but my understanding is that proj4 mostly
> ignores geogcs transforms. There are a few exceptions to this rule,
> but it is mostly true, since proj4 was originally written without any
> geogcs transform support at all. The support which is there was
> retrofitted in later by Frank Warmerdam.
> Frank can correct me, of course... :)
> Luis Mota wrote:
>> Hi everyone.
>> I've been using the transform function, but I have some surprising
>> For instance, if I issue the following query:
>> select transform(geomfromtext('POINT(0 38)',4803),4326);
>> the result I get is:
>> transform -----------------------
>> SRID=4326;POINT(38 0)
>> (1 row)
>> ie, exacly the same point... This is obviously wrong, since the two
>> GEOGCS's are different. For instance, the prime meridian is different..
>> Is it possible that I have some instalation problem? Was this a bug
>> corrected in a later version?
>> Thanks for any help.
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