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I'm trying to convert a bmp image in BNG to WGS84 using gdalwarp (via QGIS). It seems to be running without errors but the output is all black. What am I doing wrong?

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up vote 2 down vote accepted

Did you try it outside of QGIS (e.g. via command line?) - that would be the first thing to test.

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specfically I used the verison of gdal that FWTools provides to get it to work – jk. Feb 20 '11 at 7:21

When I was doing some cropping of geotiff images with gdalwarp, my mask was making the area that I wanted dropped all black. A co-worker advised that the direction of the coordinates could be the issue. Apparently drawing coordinates in one direction (Clockwise for example) will keep everything outside the crop area and the other way (counter clockwise) will keep everything inside of the drop area. When I changed the direction of my cutline coordinates, it did what was expected. Hope this helps.

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