I want to substract two covering raster sets in the Raster Calculator in QGIS to get a difference map. The raster sets have different extents and raster size.
How does the algorithm of Raster Calculator exactly interpolates the difference raster?
I am not sure what do you mean by raster size whether it is a synonym of raster extent or not, or you mean a raster resolution. Anyway let me explain how raster calculator works when you two raster data of different extents.
When you have a situation that you need to do a calculation involving two raster data of different extents as in the following example, you need to choose the output extent by selecting one of the input raster data (Raster bands) as you can see below:
- Select a an input under
- Click on
Current layer extent
- The X min, Y min, X max, and Y max will be updated based on the extent of the selected input raster. In the above image
If I select the second image:
DEM_Full@1 and click on
Current layer extent, the extent will be updated: