simple map algebra

Discussion created by rockjock23 on Feb 19, 2012
Latest reply on Feb 23, 2012 by PBhattarai-esristaff
I'm having trouble getting the raster calculator to work in ArcMap 10.3 with spatial anlayst extension. I'm using the raster calculator to do something simple like add or subtract 100 from each cell in the raster. I use the following expression Float ("raster") - 100.0 The tool runs fine, but the results are strange. A DN in the original raster of 47 returns a value of -36. A DN of 26 returns a -48. I've also tried dividing two rasters (using Float), when I do that I get all 1's.

Please advise.