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I am stringing together a series of raster calculations in the QGIS process modeler in order to calculate a surface temperature dataset from Landsat and weather data.

When I use the output from multiple prior algorithms in the model as the input for a raster calculation, the result is a blank grid (-1.79769e+308 to 1.79769e+308). Calculations performed with input parameter bands work as expected.

This issues appears to have been addressed in this QGIS bug report.

However I've updated my install and the problem persists. Can anyone advise on this? I'd rather not split my model into several smaller models.

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  • Are you using the Qgis raster calculator or the gdal one? I have found in the graphical modeler the gdal one is more straight forward to link. – Baswein Aug 2 '19 at 2:43
  • Thank you, I was using the QGIS raster calculator -- switching to gdal fixed the problem. – gmcgowan Aug 3 '19 at 13:04
  • Glad that worked- I created an answer for future frustrated users. If you could accept it that would be great. – Baswein Aug 3 '19 at 14:02
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There are 3 raster calculators that you can use in the graphical modeler: Native Qgis, Saga, and GDAL. I have found the gdal one to work better than the native Qgis one in the modeler because it is set up to define your inputs as raster1 = A and raster2 = B first and then use them in your equation. For example A+B. I have not used the SAGA one.

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