[Qgis-user] Helmert transform in Georeferencer plugin is broken

[Tim Sutton]

Hi

I suggest asking Marco Hugentobler about this. Filing a bug would
probably be a good idea too - it would be helpful if you can include
some test data with any bug report you file. Contact me if you need an
account on https://svn.qgis.org/trac to file your report.

Regards

Tim

2007/12/5, peter <webtmc at telusplanet.net>:
>
> I did some more testing with the Georeferencer plugin...
>
> If I do a linear transform, my georeferenced aerial photo loads fine, the UTM
> coordinates are correct, and the vector shape file loads over top of the
> photo. Both layers are in the same extent. Everything works as it should,
> although the roads of the vector layer do not quite line up with the roads on
> the raster photo. The photo needs to be rotated slightly, which is why I need
> to do a Helmert transform...
>
> However, if I try to do a Helmert transform, the resultant raster and vector
> files are not in the same extent. The vector layer appears as a little dot to
> the left and off of the raster layer, even though the raster is actually a
> small portion of the vector layer area. The coordinates on the raster layer
> look more like the x,y coordinates of the raster pixels, rather than the UTM
> coordinates.
>
> In discussing this on the #qgis chatroom, it appears as though the world file
> is incorrect after the transform.
>
> The linear world file is:
> 1.258047197754220
> 0
> 0
> -1.152181167169244
> 363616.681031816115137
> 5513234.182411503046751
>
> However the Helmert modified world file is:
> 1.000000000000000
> 0
> 0
> -1.000000000000000
> 363627.532545701600611
> 5513436.412385137751698
>
> Does this sound like it could be a bug in the plugin? Any other ideas? Thanks.
>
> --
> Peter Pankonin, digitalcrucible
>
> There are 10 kinds of people in the world,
> those who understand binary, and those who don't.
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-- 
Tim Sutton
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