[Qgis-developer] Georeferencer produces wrong (shifted) result

[Werner Macho]

Very good idea..
Implementing a known problems per release seems possible to me. But it can
only be a webpage cause at the time of release you mostly are not aware of
the problems..
Regards
Werner
Am 17.12.2011 21:07 schrieb "Agustin Lobo" <alobolistas at gmail.com>:

> Many thanks Manuel.
> No hurry for including the patch, once the problem is identified and
> you even provide a simple way to circumvent it.
> What is needed is to have users know of these potential problems, ie.
> through
> a note of "Known Problems" included in the release mentioning that
> "the Georeferencer plugin requires users to check that their files do
> not include
> an implicit geotransform and use e.g.
> "gdal_translate -co "PROFILE=BASELINE" -of GTiff Ilerfly125v2.tif
> Ilerfly125v2-nogeotrans.tif"
> to remove it in case this is actually needed".
> In other words, once the problem is identified and warned, users can
> rely on using the software for the rest of cases.
> The question is thus that, in addition of the excellent developers
> already involved,
> we need a team of users and a battery of tests to be regularly performed.
> Agus
>
>
>
>
>
>
> 2011/12/17 Manuel Massing <m.massing at warped-space.de>:
> > Hi Agustin,
> >
> >
> >> The points are correct (therefore the errors etc), but the
> >
> >> georeferenced image is shifted. May be the datum is not taken into
> >
> >> account
> >
> >> when the georeferenced image is created.
> >
> >
> > I did a clean checkout, and could finally reproduce the problem:
> >
> > it stems from the fact that your input file has a geotransform,
> >
> > which flips the yaxis of the local coordinate system and changes the
> >
> > origin. As the geotransform plugin does not handle geotransform
> >
> > info correctly, this results in the shift you have observed.
> >
> >
> > Removing the geotransform (e.g. using "gdal_translate -co
> "PROFILE=BASELINE"
> > -of GTiff Ilerfly125v2.tif Ilerfly125v2-nogeotrans.tif") should give you
> >
> > a file which the georeferencer can handle correctly (you may have to
> delete
> > the accompanying .aux file, if gdal uses this to keep the geotransform).
> >
> >
> > I had a local patch in the georeferencer which handles geotransform
> >
> > information, so this is why I couldn't reproduce the problem (talk about
> a
> >
> > mixture of good and bad luck :-)). I will see what is required to make my
> >
> > local changes ready for submission, so we can avoid such subtle problem
> with
> >
> > georeferenced/pseudo-georeferenced files in the future. As I already
> >
> > mentioned, due to an important deadline at work, I have little time to
> >
> > dedicate to this atm, so it may take a few day... is there a release in
> the
> >
> > pipeline?
> >
> >
> > cheers,
> >
> >
> > Manuel
> >
> >
> >
> >
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> > Qgis-developer at lists.osgeo.org
> > http://lists.osgeo.org/mailman/listinfo/qgis-developer
> >
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