Foursquare, the location-based social network, has put together a series of videos tracking "the pulse" of various metropolises -- New York, San Francisco, London, Chicago, Tokyo and Istanbul -- using check-in data from its users. The resulting animated maps are gorgeous, all black backgrounds, stark white lines and neon movement creating the effect of stained glass in motion.
What the maps show is fascinating: cities moving to the rhythm of the day, each with its distinct commute, shopping, dinner, clubbing, bedtime. Transit lines are traced in turquoise, and parks are saturated with lavender.
But because the maps sample only Foursquare users and their behavior, they don't necessarily offer an accurate representation of a city's population or density; instead the maps favor the habits of the wealthy, the young and those with leisure time. Examining other social media users -- for example, those on Twitter -- generates similar demographic maps.
Head over to Foursquare's Vimeo account and check out the rest of the maps; they're beautiful. But don't confuse them for more than what they are.