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I am using QGIS 3.10 and try to solve the following task. I have a multiband raster (4 bands in total), where each band represents the spatial extent of a tropical storm and the respective pixel value represents the wind speed.

In other words, the multiband raster contains all tropical storms within a given area for a respective year. In this case there have been 4 tropical storms, represented by the 4 bands. Now I want to create a singleband raster containing the max value of the 4 rasters, so that the new singleband raster image contains the maximum wind speed exposure for cell i in year t. If a cell was hit by two storms, I want to assign the value of the band with the higher wind speed.

The question in short is: How do I tell QGIS to compare the raster values of all bands and then choose the highest one. I tried the raster calculator, but I could not figure out a suitable option and I am not really familiar with the syntax in the raster calcaaltor.

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you can use the rastercalculator for that with an expression like this one:

("raster@1" >= "raster@2" AND "raster@1" >= "raster@3" AND "raster@1" >= "raster@4") * "raster@1" +
("raster@2" > "raster@1" AND "raster@2" > "raster@3" AND "raster@2" > "raster@4") * "raster@2" +
("raster@3" > "raster@1" AND "raster@3" > "raster@2" AND "raster@3" > "raster@4") * "raster@3" +
("raster@4" > "raster@1" AND "raster@4" > "raster@2" AND "raster@4" > "raster@3") * "raster@4"

where raster is your rasterlayer

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  • Awesome, thank you so much for the help.
    – Random_GIS_dude
    Apr 15, 2021 at 18:52

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