I have some GeoTiff's that are in EPSG:3006 (SWEREF99 TM) atm, and I'm trying to convert them to EPSG:4326 (WGS84) because some other software needs it in this projection.

But after doing the gdalwarp the corners of my tiff's doesn't seem to add up anymore. Is there anything i can do to prevent this from happening?

Some examples (from gdalinfo); the upper right corner of one tile should be in the same position as the upper left corner on the next tile.

The corners in EPSG:3006:

Upper Right (  400000.000, 6200000.000) ( 13d23'57.18"E, 55d56' 5.91"N)
Upper Left  (  400000.000, 6200000.000) ( 13d23'57.18"E, 55d56' 5.91"N)

And the same corners ins EPSG:4326 after gdalwarp:

Upper Right (  13.4282324,  55.9349761) ( 13d25'41.64"E, 55d56' 5.91"N)
Upper Left  (  13.3992179,  55.9453750) ( 13d23'57.18"E, 55d56'43.35"N)

Now they don't line up anymore.

I'm using QGIS, which is using gdalwarp to do this. The commandline for the operation:

gdalwarp -overwrite -s_srs EPSG:3006 -t_srs EPSG:4326 -of GTiff C:/data/example.tif C:/data/example_warped.tif

They are not the same corners. Warping rotetes the image and I hope that this image explains the rest.

enter image description here

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  • Thank you! I'm pretty new to this so I thought i could do it that way. Is there any other way to do what i want? – bjarven Apr 19 '16 at 15:07
  • I thought about merging all the tiff's in EPSG:3006, then warp the merged tiff, and split it up into many tiff's again. Could that be a solution perhaps? – bjarven Apr 19 '16 at 15:09
  • You can do it that way. The image areas do stand side by side after conversion but you must make the sliver triangles transparent by assigning a NoData value with -dstnodata or alpha channel with -dstsalpha gdal.org/gdalwarp.html. Merging first, rotating then is good suggestion. Which approach is better depends on use case. – user30184 Apr 19 '16 at 15:13

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