PlayaroundNYC [playaroundnyc.com] is an interesting example of where social visualization meets captology. The website was specifically created to help New Yorkers explore how well their neighborhoods are supported by playgrounds and to investigate how this support is tempered by nearby conditions. The aim is that with better understanding, New Yorkers will be in a better position to act to both improve the availability and quality of neighborhood playgrounds.
The neighborhood playground support map is the result of combining several different types of data sets. First, each playground was assigned a quality rating. Currently quality is mainly determined by nearness to major and minor truck routes. A grid of points were then sampled on the map, by determining the nearest playgrounds, walking distance to these playgrounds, and the quality of these playgrounds. These factors are combined to assign each point an overall rating which estimates how well that area is supported by playgrounds. Lastly, the various support ratings are interpolated to generate the heatmap visual effect.