On mercredi 30 novembre 2016 06:44:11 CET Mark Johnson wrote: > This may be a similar problem to what was mentioned here: > > #6721: Simplifing use of gdalwarp with cutline with non-georeferenced > rasters > > https://trac.osgeo.org/gdal/ticket/6721 > (which has not been reacted to) > > There the gal was to use gdalwarp, together with a cutline, to cut out a > portion of the non georeferenced raster (sample: image with folds which > need to be removed). > > Here the idea was to emulate any meter base system (such as 3395 WGS 84 / > World Mercator), creating a world file that always looks like this: > > 1.00000000000000 > 0.00000000000000 > 0.00000000000000 > -1.00000000000000 > 0.00000000000000 > 0.00000000000000 > > Sample: small non georeferenced raster map from Wiki (1200x864): > wget > https://upload.wikimedia.org/wikipedia/commons/a/a0/Karte_berlin_akzisemauer > .png -O 18550101.Karte_berlin_akzisemauer.wiki.png > echo -e "1.00000000000000\n 0.00000000000000\n 0.00000000000000\n > -1.00000000000000\n 0.00000000000000\n 0.00000000000000" > > 18550101.Karte_berlin_akzisemauer.wiki.pgw > gdal_translate -a_srs epsg:3395 18550101.Karte_berlin_akzisemauer.wiki.png > 18550101.Karte_berlin_akzisemauer.wiki.ref_3395.tif > gdalinfo 18550101.Karte_berlin_akzisemauer.wiki.ref_3395.tif > > Using '-te' create a cutline around the boundry shown on the map > - remembering the 'y/height' is always minus (i.e top=0, bottom=height*-1) > --> top=-50 ; bottom=-690 > > gdalwarp -s_srs epsg:3395 -t_srs epsg:3395 -te 220 -690 1160 -50 > 18550101.Karte_berlin_akzisemauer.wiki.ref_3395.tif > 18550101.Karte_berlin_akzisemauer.cut.ref_3395.tif > > Without a world file you get with: > gdalwarp -s_srs epsg:3395 -t_srs epsg:3395 -te 220 -690 1160 -50 > 18550101.Karte_berlin_akzisemauer.wiki.png > 18550101.Karte_berlin_akzisemauer.cut.ref_png.tif > > ERROR 1: The transformation is already "north up" or > a transformation between pixel/line and georeferenced > coordinates cannot be computed for > 18550101.Karte_berlin_akzisemauer.wiki.png. > There is no affine transformation and no GCPs. > Specify transformation option SRC_METHOD=NO_GEOTRANSFORM to bypass this > check. > > (which is what you got) > What the meaning of is: SRC_METHOD=NO_GEOTRANSFORM > - no idea
This error is emitted when the source dataset has no geotransform (and no GCP and no RCP and no geolocation array), or has a geotransform which is the identity matrix. Both cases are usually non-nominal cases of gdalwarp. If you really want to proceed with the identity geotransform, then you have to specify -to SRC_METHOD=NO_GEOTRANSFORM to gdalwarp. Even -- Spatialys - Geospatial professional services http://www.spatialys.com
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