I decided to compare the unmodified imagery of Oakland’s City Hall Plaza with the same location after 3 derivative maps (specifically a detail from Oakland Quilt #5). The result is quite interesting because it shows that the template I’ve been using for almost a year is not 100% perfect, which I knew already, but never cared to quantatively find out.
First there is too much light because the imagery on the right is slightly brighter. I did not compare the RGB histograms to see exactly how bright it is, but will check out in the future. Secondly, and more importantly, the template ever-so-slightly over-projects the imagery. The visual result is a slightly fuzzy version of the original, which, in most cases, does not matter because it’s ONLY noticable when shown at it’s full size. Once the map is reduced in size the fuzziness goes away.
To discover this I placed the original imagery on top of the used imagery and changed the opacity so that I could line up park on top each other and to match them I had to stretch the original imagery about .03%. Which after being used for 3 maps, this means my current template over-projects the imagery approximately .01%. This isn’t all the bad, but it means I need to do a slight resize to the template. Technically this means each map is 180 pixels too large, but honestly, I find that number a bit too high….