This map shows the intensity of tweets about Paris’ transit system, RER. The map utilizes Google Maps API’s new heat mapping capability. Interestingly, the tool demonstrates the ability to alter opacity, colour ramp, layer presence (on or off), and size (kind of like raster pixel resolution). One problem is that legends are not automatically produced for these maps. To create a legend, additional code must be added (to the best of our knowledge, ex: Issue 37). The algorithm for calculating the heat map is also unclear. Regardless, the visual effect is compelling and exciting!
(Via Google Maps Mania)