Hi Bart, On Tuesday 08 December 2009 12:33:10 bart...@osgis.nl wrote: > in ArcMap I see negative values, in GDAL all values seem to have a shift > of 256, so -21 becomes 235. Nodata values are also off with 256, so -256 > in ArcMap becomes 0 in GDAL.
The pixel type of your input is char (signed 8 bit). The no-data value is -256 (which cannot be represented by the signed 8 bit, btw). For some reason your data gets converted from a signed 8 bit type to an unsigned 8 bit type. Looking at the trunk version of sderasterband.cpp I see that GDT_BYTE is taken to be the equivalent of SE_PIXEL_TYPE_8BIT_S. If this means that an input of signed 8 bit value is stored in an unsigned 8 bit value, than that would explain what you are seeing. An alternative would be to update this code to return GDT_Int16, which will leave your data intact. Line 833. Special care may have to be taken to handle the no-data values correctly. Probably the original author will have something to say about this. Kor _______________________________________________ gdal-dev mailing list gdal-dev@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/gdal-dev
