If you get the ZCTA polygons, it seems that overlaying polygons with opacity set to something low might be pretty easy. Should be really simple to get number of press releases sent to each zip code and relate that to the opacity of the polygon. If you put multiple polys on top of one another, their opacities add (say you could overlay one copy of a ZIP code polygon with low opacity for every X number of press releases), or maybe you could set the opacity based on some formula if you don't want a linear relationship. For example, logarithmic: is 10 vs 100 the same as 100 vs 1000? The contrasts are different on a linear scale (90 vs 900) but the same logarithmically (10-fold).
I haven't accessed/set the opacity of a polygon programatically, but it probably can be done (anyone have an example?) -Brian On May 8, 11:20 am, "Maps.Huge.Info (Google Maps API Guru)" <[email protected]> wrote: > Doing heat maps with the API almost always requires constructing a > custom tile layer. Doing so by zip codes is not trivial. If you use > the Census's Tiger based ZCTA polygons, at least it would be free. > > Here's an example of using Tiger's ZCTA's on a zip code map, albeit > this is not a heat map: > > http://maps.huge.info/zcta.htm > > -John Coryat > > http://maps.huge.info > > http://www.usnaviguide.com > > http://www.zipmaps.net --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Maps API" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/Google-Maps-API?hl=en -~----------~----~----~----~------~----~------~--~---
