I am using QGIS 3.8 and I am trying to merge three rasters according to the scheme pictured on the attached screenshot. I tried many syntax expressions for the Raster calculator but I was unable to get the desired result (merged raster).
Does anybody have any idea how to merge the rasters? Each raster is categorized to 4 groups based on pixel values. The range of groups is same for all rasters - 4 = red color, 3 = blue color, 2 = brownish color, 1 = yellow color (not present on the screenshot).