[Qgis-developer] Qgis 1.7.4 not using '+towgs' proj parameters when OTF reprojection

Ivan Mincik ivan.mincik at gmail.com
Fri Mar 9 08:19:46 EST 2012

On 03/09/2012 12:31 PM, Craig Leat wrote:
>> It seems that latest 'release-1_7' build (and most probably in 1.7.4) is
>> not using '+towgs' proj parameters when using on-the-fly reprojection.
>> It is visible when overlaying two layers in different projection where
>> 'towgs' parameter is needed to reproject data accurately. Currently the
>> error is the same as it would be without specifying 'towgs' parameter.
>> It was working nicely in older 1.7 releases.
> +towgs works for me on 1.7.4, but I have to specifically set the CRS
> for the layer because it's not recognised when loading the layer. See
> bug #5071. If you manually select the CRS from the layer properties
> dialogue does it work?

Craig, thanks for the answer.
I have found that Qgis is not using 'towgs' only if using one of the
projections from installed projection database. If I create custom
projection by 'Settings -> Custom CRS' it is working correctly.

To get things more clear, I am inserting missing projection (see #4945)
to internal database before building. This projection is using 'towgs'.

Ivan Mincik

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