[Qgis-user] Raster calculator

[Hanlie Pretorius]

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 at 1 - low input at 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
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