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I get an error when trying to warp a tif file in QGIS:

ERROR 1: Too many points (35721 out of 35721) failed to transform, unable to compute output bounds.

I am using QGIS 1.7.0 Wroclaw with gdal 1.8. I am trying to reproject from ETRS89 to HD72 EOV. There was an error in the data, with the UTM zone added to the eastings. That is, the x coordinates read 34327213.050 when they should read 327213.050 in UTM zone 34N. I have tried changing the .tfw file but this did not help. Then I translated the tif to a .vrt and edited the vrt, removing the rogue 34, and fixing the extent. This also did not help - I still get the same error when I try to warp. In layer properties, this raster now has the same origin, extent and SRS as other similar rasters, but only this one gives the error.

How do I work this out? Any suggestions will be greatly appreciated.

Cheers, Rudi

ps. A similar question was asked 4 months ago, but it was not the exact same problem, and the OP never explained how the problem was resolved.

Edit: as suggested, here is a link to the related question

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2 Answers 2

So here is the quick and dirty solution to my problem. I have both a *.tif and *.twf for each raster. Combining several suggestions I saw on other sites, I opened the GeoTiffs in a photo editor (PSP 5 in my case, but gimp would also work) and saved as a plain tiff, thereby removing the metadata. Then I edited the .twf to remove the 34 in the easting, and saved this with the same name as the new, non-georeferenced tiff. QGIS then looked to the twf file for the geographic info, and I was able to re-project the rasters.

Edit: Or, alternatively, one could get a little program called geotiff examiner, and use that to update the referencing for the tif and the twf. All it does is modify the geo tags. Or, one could use the method described in the answer by MerseyViking.

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Have you tried using gdal_translate to fix the error? Something like this should work:

gdal_translate -a_srs EPSG:32634 -a_ullr <actual coordinates go here> broken.tif fixed.tif

The order of the coordinates should be: left, top, right, bottom.

This should ignore everything that's in the TIFF's metadata and overwrite it with the proper bounds and projection. Also, by default, it'll embed the bounds in the TIFF rather than relying on a .tfw, so don't worry if one isn't created with your new file.

A link to the previous question might be useful, even if its not exactly the same issue.

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Thanks! I will try this as soon as I get a chance, because I think it sounds like a better long-term option. In the meantime, I discovered the work-around described in my answer. –  Rudi Nov 22 '11 at 0:03
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