Basically what I'm trying to do (in ArcGIS 10) is to compare three vector files in order to create a 'comparison' raster layer. I tried using Data Comparison (under Data Management tools) but it didn't output what I was looking for. I basically wanted to create a raster surface that shows where each type of polygon overlaps. So for example if layer a and b overlap at some point, the raster pixel value will reflect that (and if a, b and c overlap, etc.). I can't figure it out and I've been browsing ArcMap's help for ages.