[Qgis-developer] [Fwd: Re: [Qgis-user] projection bug?]

Maciej Sieczka tutey at o2.pl
Sat May 10 08:40:02 EDT 2008


Paolo Cavallini pisze:
> Maciej Sieczka pisze:
>> Paolo Cavallini pisze:

>>> Testing 0.10 from debian.gfoss.it we noticed that on the fly
>>> projection apparently is not working. Does anybody confirm this?

>> I have 0.10.0 + SVN 8401 installed and OTF works for me.
>> 
>> Check if your layer you want to re-project has a correct SRS
>> assigned.
>> 
>> QGIS fails to recognize many SRSes at layer load time, due to a
>> change in GDAL [1].
>> 
>> [1]http://www.nabble.com/forum/ViewPost.jtp?post=16592790&framed=y

> anybody has a solution to this?

The only "solution" I know of for now is to revert back to GDAL 1.4.2
(the last release not including the mentioned change).

Another would be to trim off the spurious zeros from k parameter in QGIS
srs.db. Although this would break compatibility between QGIS and GDAL <
1.4.4 it should not be an issue as GDAL 1.4.2 is pretty old now.

However, deleting these zeros might break QGIS interaction with POSTGIS,
as even the newest 1.3.3 release stores k paramaters with extra zeros in
spatial_ref_sys table, column 'proj4text column'. QGIS devs - is this
guess correct? I already asked about that on the ML but here was no
response. Any feedback will be very appreciated so it can be decided if
deleting these zeros is safe.

Ideally, QGIS should compare numerical values of SRS parameters, not
strings as it does now, so that eg. it considered 0.999300 equal 0.9993
and no problem. QGIS devs - could this be applied?

Note that there is another related bug in GDAL > 1.4.4 [1], which also
prevents SRS recognition is QGIS. Fixed in trunk, awaiting to be
backported to 1.5 stable branch. Once this is done and once we decide if
to delete the offending zeros in srs.db, I'll get back to updating
srs.sb to match the latest EPSG database used in PROJ and GDAL.

[1]http://trac.osgeo.org/gdal/ticket/2036

Maciek


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