What I want to do is pretty straight forward: I have two raster with the same crs, resolution and extent. Both rasters show the number of days an area is flooded so they just have two values. Raster a consists of 0 and 183; raster b of 0 and 149. Logically, the area that is flooded only 149 days (b) is a little bigger than the area that is flooded 183 days (a).
Now I want to combine both maps. The formula I think should work using the saga raster calculator is:
ifelse(eq(a,0), b, a) .
In my opinion it translates to "If a pixel of map a is equal to 0 then use the pixel value of map b if not, keep the pixel value of a" So the result should be a map having just three values: 183, 149 and 0, right? But no, the resulting map has all kind of weird (i cannot explain them) values where map a is 0 and map b is 149. It seems like some transition from 183 over 149 to 0.
Why is that, or is it a bug?