<br><br>---------- Forwarded message ----------<br><span class="gmail_quote">From: <b class="gmail_sendername"><a href="mailto:gdal-dev-request@lists.maptools.org">gdal-dev-request@lists.maptools.org</a></b> <<a href="mailto:gdal-dev-request@lists.maptools.org">
gdal-dev-request@lists.maptools.org</a>><br>Date: 10-dic-2006 18:02<br>Subject: Gdal-dev Digest, Vol 31, Issue 22<br>To: <a href="mailto:gdal-dev@lists.maptools.org">gdal-dev@lists.maptools.org</a><br><br></span>Send Gdal-dev mailing list submissions to
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<br>than "Re: Contents of Gdal-dev digest..."<br><br><br>Today's Topics:<br><br> 1. Re: ogr2ogr Default Output SRS (Martin Spott)<br> 2. Re: ogr2ogr Default Output SRS (Frank Warmerdam)<br><br><br>----------------------------------------------------------------------
<br><br>Message: 1<br>Date: Sat, 9 Dec 2006 19:15:43 +0000 (UTC)<br>From: Martin Spott <<a href="mailto:Martin.Spott@mgras.net">Martin.Spott@mgras.net</a>><br>Subject: Re: [Gdal-dev] ogr2ogr Default Output SRS<br>To:
<a href="mailto:gdal-dev@lists.maptools.org">gdal-dev@lists.maptools.org</a><br>Message-ID: <<a href="mailto:elf20v$oag$1@osprey.mgras.de">elf20v$oag$1@osprey.mgras.de</a>><br><br>Hi Frank, thanks for responding,<br>
<br>Frank Warmerdam wrote:<br><br>> There are some "sensitivities" in how ogr2ogr identifies which SRID to use<br>> in postgis. If it doesn't find a match then it creates a new SRID at the<br>> "top" of the table, which I suspect did for the 32767 case.
<br>><br>> It may be that the spatial_ref_sys tables in your different versions of<br>> postgis are slightly different in the formatting of the WKT entries and<br>> this is in one SRID 4326 gets used and in the other it doesn't.
<br><br>But what can a user actually do about this, whose "fault" is it if<br>'ogr2ogr' and PostGIS don't place together nicely, and, which I<br>consider even more important, which route to take to solve this issue ?
<br><br>Apparently PostGIS started shipping newer versions of the<br>spatial_ref_sys table with 1.1.6 and 'ogr2ogr' somehow doesn't 'agree'<br>with the contents of this table.<br>I just ran a test with PostGIS-1.2.0 - same effect as with
1.1.6, still<br>using the respective spatial_ref_sys that comes with the very PostGIS<br>release. I then pushed the contents of the spatial_ref_sys table from<br>PostGIS-1.1.5 into the DB, still running PostGIS-1.2.0, and everything
<br>is fine. So, is this sort of a bug in 'ogr2ogr' that shows some<br>incapability to handle newer EPSG declarations or is this to be<br>considered as a misfeature in the recent EPSG files that breaks<br>'ogr2ogr' ?<br><br>
Cheerio,<br> Martin.<br>--<br> Unix _IS_ user friendly - it's just selective about who its friends are !<br>--------------------------------------------------------------------------<br><br><br>------------------------------
<br><br>Message: 2<br>Date: Sun, 10 Dec 2006 00:24:34 -0500<br>From: Frank Warmerdam <<a href="mailto:warmerdam@pobox.com">warmerdam@pobox.com</a>><br>Subject: Re: [Gdal-dev] ogr2ogr Default Output SRS<br>To: <a href="mailto:Martin.Spott@mgras.net">
Martin.Spott@mgras.net</a><br>Cc: <a href="mailto:gdal-dev@lists.maptools.org">gdal-dev@lists.maptools.org</a><br>Message-ID: <<a href="mailto:457B9A12.6080906@pobox.com">457B9A12.6080906@pobox.com</a>><br>Content-Type: text/plain; charset=ISO-8859-1; format=flowed
<br><br>Martin Spott wrote:<br>> Hi Frank, thanks for responding,<br>><br>> Frank Warmerdam wrote:<br>><br>>> There are some "sensitivities" in how ogr2ogr identifies which SRID to use<br>>> in postgis. If it doesn't find a match then it creates a new SRID at the
<br>>> "top" of the table, which I suspect did for the 32767 case.<br>>><br>>> It may be that the spatial_ref_sys tables in your different versions of<br>>> postgis are slightly different in the formatting of the WKT entries and
<br>>> this is in one SRID 4326 gets used and in the other it doesn't.<br>><br>> But what can a user actually do about this, whose "fault" is it if<br>> 'ogr2ogr' and PostGIS don't place together nicely, and, which I
<br>> consider even more important, which route to take to solve this issue ?<br><br>Martin,<br><br>Normally there is no great harm in creating a new SRID for what is a<br>slightly different formatting of a coordinate system that from a
<br>meaningful point of view matches an existing SRID.<br><br>However, the solution, I think would be for OGR to:<br><br> o Do the search based on the proj.4 string rather than the WKT.<br> The proj.4 strings are less likely to suffer from formatting
<br> variations over time.<br><br> o Provide a mechanism (a layer creation option for instance) so<br> that the user can force use of a particular SRID whether OGR<br> thinks the coordinate systems match or not.
<br><br>> Apparently PostGIS started shipping newer versions of the<br>> spatial_ref_sys table with 1.1.6 and 'ogr2ogr' somehow doesn't 'agree'<br>> with the contents of this table.<br>> I just ran a test with
PostGIS-1.2.0 - same effect as with 1.1.6, still<br>> using the respective spatial_ref_sys that comes with the very PostGIS<br>> release. I then pushed the contents of the spatial_ref_sys table from<br>> PostGIS-1.1.5
into the DB, still running PostGIS-1.2.0, and everything<br>> is fine. So, is this sort of a bug in 'ogr2ogr' that shows some<br>> incapability to handle newer EPSG declarations or is this to be<br>> considered as a misfeature in the recent EPSG files that breaks
<br>> 'ogr2ogr' ?<br><br>Note that the spatial_ref_sys for PostGIS is generated with OGR. So<br>there is no reason to believe the newer spatial_ref_sys will differ<br>from what newer OGR versions expect. Upgrading GDAL/OGR may therefore
<br>help.<br><br>Generally speaking comparing coordinate systems is *hard*. Especially if<br>you wish to do so efficiently.<br><br>If you file a bug against OGR with the two earlier suggestions, I'll try<br>and have them implemented at some point. Ideally in time for the GDAL
<br>1.4.0 release.<br><br>Best regards,<br>--<br>---------------------------------------+--------------------------------------<br>I set the clouds in motion - turn up | Frank Warmerdam, <a href="mailto:warmerdam@pobox.com">
warmerdam@pobox.com</a><br>light and sound - activate the windows | <a href="http://pobox.com/~warmerdam">http://pobox.com/~warmerdam</a><br>and watch the world go round - Rush | President OSGeo, <a href="http://osgeo.org">
http://osgeo.org</a><br><br><br><br>------------------------------<br><br>_______________________________________________<br>Gdal-dev mailing list<br><a href="mailto:Gdal-dev@lists.maptools.org">Gdal-dev@lists.maptools.org
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