Hi, I think I do not understand something simple, but how a byte type pixel can have one half as a value?
0.5 0.5 1 -Jukka Rahkonen- ________________________________________ Lähettäjä: gdal-dev <[email protected]> käyttäjän Daniel Baston via gdal-dev <[email protected]> puolesta Lähetetty: Torstai 13. marraskuuta 2025 16.40 Vastaanottaja: Henry Walshaw <[email protected]> Kopio: [email protected] <[email protected]> Aihe: Re: [gdal-dev] GDAL CLI converting to output datatype before performing calculation Hi Henry,The input values should not be rounded before doing the calculation. I get a correct result with both 3.12 and 3.11.5:$ gdal raster create --size 1,1 --burn 0.1 --output-data-type Float64 depth.tif$ gdal raster calc -i "A=depth.tif" -o footprint_b.tif --calc "A > 0 ? 1 : 0" --nodata none --ot Byte$ gdal raster convert footprint_b.tif --output-format XYZ /vsistdout/ERROR 6: Read or update mode not supported on /vsistdout0.5 0.5 1DanOn Thu, Nov 13, 2025 at 12:49 AM Henry Walshaw via gdal-dev <[email protected]> wrote:Hi all,In the docs for gdal raster calc (https://gdal.org/en/stable/programs/gdal_raster_calc.html#cmdoption-calc) it statesInput rasters will be converted to 64-bit floating point numbers before performing calculations.However I’ve found that when using an integer output datatype the base data is rounded to an integer before performing the calculation. e.g. converting a flood depth input.tif raster to a simple water / no water footprint: gdal raster calc -i "A=depth.tif" -o footprint_b.tif --calc "A > 0 ? 1 : 0" --nodata none --ot Byte The expected result for a value of (say) 0.1 is 1, but in the above calculation it comes out as 0. Obviously I can leave the output datatype alone so it stays the same as the input’s 64-bit float, but it seems unnecessary. Am I looking at a bug, or is this expected behaviour?Regards,Henry​_______________________________________________gdal-dev mailing [email protected]https://lists.osgeo.org/mailman/listinfo/gdal-dev _______________________________________________ gdal-dev mailing list [email protected] https://lists.osgeo.org/mailman/listinfo/gdal-dev
