Hi Hanlie, I too have found "interesting" results returned by the raster calculator and usually default to loading the data into GRASS and processing it there. I suspect you may need to convert your input data to *.tif format for the equation to work in QGIS. This is easily done using gdal_translate or the gdal_translate implementation in QGIS -> Raster/Conversion/Translate
Not sure why you are having trouble with the ASC files, perhaps the conversion will do the trick Regards, Wesley On Wed, Feb 20, 2013 at 10:24 PM, Hanlie Pretorius < [email protected]> wrote: > Hi, > > If there's a way to search the whole archive of this list in one go, > please let me know. > > Otherwise, can someone perhaps help me with this problem? > > I'm using the raster calculator in QGIS 1.8.0 on Windows 7 to find the > difference between two rasters. The two input rasters (ASC files) both have > float32 datatypes and they have exactly the same spatial extent. The > expression I use in the calculator is: > > med input@1 - low input@1 > > *med input* has a range from 0 to 5.5 > *low input* has a range from 0 to 2.5 > > The result I get is a float32 output raster with zero everywhere. I have > tried two different output formats - TIFF and IMG with the same result. > > I have also tried to add the two rasters, with the same result - zero > everywhere. > > I imported the input rasters into GRASS, performed the calculation, got > the correct result, and exported the output successfully to a TIFF file. > > Can anyone help me figure out why the raster calculator in QGIS is not > giving the expected result? > > Thanks > Hanlie > > _______________________________________________ > Qgis-user mailing list > [email protected] > http://lists.osgeo.org/mailman/listinfo/qgis-user > > -- Dr Wesley Roberts [email protected] Cell: +27(0)83 5355 646 skype: roberts-w
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