(Check out the big version!)
I've had this idea to use subtractive blending so that you can see
where these three data sets overlap for a while, and decided to
scratch the itch this weekend. I'm still not sure if it's significant
or even interesting, but here it is. This is a slightly improved
the original with a more useful (and attractive!) legend and no base map. The
colors have also changed: Trees are cyan and crimes magenta because I
felt that the latter should stand out more. And yellow combines with
magenta to produce red, which seems to me a more crime-y color.
Urban tree locations come courtesy of Friends of the Urban Forest, one day's worth of taxi cab locations from Yellow Cab (via Cabspotting), and a week's worth of reported crime incidents from Crime Reports.
Best, obviously, viewed at original size.