Le mardi 08 novembre 2011 19:18:19, Jukka Rahkonen a écrit : > Alexander Bruy <alexander.bruy <at> gmail.com> writes: > > Hi all, > > > > in gdalwarp documentation [0] listed option "-overwrite" with next > > description: > > > > -overwrite: > > (GDAL >= 1.8.0) Overwrite the target dataset if it already exists. > > > > But when I try to reproject image using next command > > > > gdalwarp -t_srs EPSG:4326 -overwrite mosaic.tif mosaic.tif > > > > i get next error > > > > Creating output file that is 9122P x 2341L. > > ERROR 4: `mosaic.tif' not recognised as a supported file format. > > > > and mosaic.tif becomes 8 bytes size file (seems only tif header). > > Is this bug or I misunderstand -overwrite option usage? > > Tested on Slackware 13.37, GDAL 1.8.1, released 2011/07/09. > > > > [0] http://www.gdal.org/gdalwarp.html
I'm not a native English speaker, but up to now, the meaning of "overwrite" has always been "delete and recreate". If you have a better wording for the doc to make it more explicit, you're welcome. The point of overwrite is that it is a common source of confusion for users (including me!) when you do : gdalwarp src.tif dest.tif -t_srs EPSG:XXXX and then you realize that XXXX is not what you want. So you try: gdalwarp src.tif dest.tif -t_srs EPSG:YYYY And you spend half and hour understanding why it has not been reprojected in EPSG:YYYY. The default behaviour being that once the target dataset exists, it is only updated, but not modified in depth. gdalwarp something.tif something.tif -t_srs EPSG:XXXX makes no sense, with or without -overwrite (and -overwrite will actually kill your target, ahem, source - since source=target - as you have seen !). Reprojection in place cannot work. You must specify a different target dataset. I can imagine that a safety check would make sense to detect such obvious error... > > I bet you do not really want to overwrite the source image with the target > image because it will make you sad. Once gdal has written a beginning of > the target "mosaic.tif" you have deleted the original "mosaic.tif" and > there is nothing more to convert. Put that command into a patch file and > you can wipe a few hundred originals in some seconds so effectively that > even data recovery companies cannot get them back. I've tried it and I do > not recommend it for anybody else. > Gdalwarp -overwrite source.tif target.tif should overwrite the old existing > target.tif and that is a reasonable command sometimes. > > -Jukka Rahkonen- > > _______________________________________________ > gdal-dev mailing list > gdal-dev@lists.osgeo.org > http://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev