simple addition in raster calculator with incorrect sums

Discussion created by kantonelis on Mar 13, 2013
Latest reply on Mar 15, 2013 by kantonelis
Hello: I am building a simple linear additive model.  I've got three reclassed rasters.  Each of them include only the values 0,1,2,3,4,5,6.

When I use the raster calculator to add them, I get what looks to be a raster with correct values for cells from 1 - 18.  However, when I run a quick QC on the output, I see that in many points the cell value is not equal to the sum of the cell values from the three original rasters.

Example: Point X
'tix' cell value = 6
'var' cell value = 6
'bathy' cell value = 5
OUTPUT Raster cell = 18

Any advice would be greatly appreciated.