The Andes project creates topographic maps of Tweets for a number of cities. It’s a remix of the Billion Strokes visualization by @miguelrios. The input data are the images featured in that visualization.
You can access the project here. Plase make sure to have a WebGL capable machine and browser.
The San Francisco elevation map shows interesting elevations “under water” in what’s the BART path from SF to Oakland. In New York we can see elevations for the ferry:
I personally like this contour map of Istanbul:
You can find the Twitter blog post about this visualization here.
Some places where this was featured: