I have a 4-bit thematic raster image with a color map from white to dark blue (Figure 1). The values 1 - 6 represent tree canopy cover at various breakpoints. I also created a raster attribute table ...
some options for merging looks like fusion tables, vizmaps, and these 2 http://mapbox.com/tilemill/docs/guides/joining-data/ ...
When mapping an value as a color to render a thematic map the objects borders can alter the map readability a lot. For example in this thematic map of the US counties with black borders: There are a ...