Composing raster files in map algebra

MariaChamilaki

Hello everyone, and thank you before hand for your help!

I am trying to calculate raster files in map algebra to compose a final map for the area and I have 4 different raster files (with the classification from 0 to 3) for land use, ex. roads, rivers, shoreline etc. When I sum the 4 rasters in map algebra I get as a result a raster file with 12 classes and not 4 (from 0 to 3) so they don't overlay.

How can I overcome this problem? 

Of course I change the symbology within the final layer to have 4 classes but I am not sure this is the correct way to go...

JayantaPoddar

What are you trying to achieve?

A sum of different combination of weights will result in more number of classes. That's obvious.

Based on what criteria you want to define for your output map, you could do the calculation (sum) or use

Weighted Overlay 

Weighted Sum 

If you feel the result is fine, and you need to further classify the results into fewer number of classes (in symbology), you could do so as well from Symbology pane.