A few years back, cycling and running app Strava mapped the paths of its users. Now with a lot more data and the challenges that come with that, Strava provides a more fine-tuned rendering of where the world cycles and runs.
Beyond simply including more data, a total rewrite of the heatmap code permitted major improvements in rendering quality. Highlights include twice the resolution, rasterizing activity data as paths instead of as points, and an improved normalization technique that ensures a richer and more beautiful visualization.
