(Photo by UC San Diego Big Pixel Initiative)

Different band combinations are used to visualize and map the boundaries of urban areas in Ahmedabad, India, in (left) 2000 and (right) 2015. Here, the built-up area detection was done using satellite imagery from Landsat (top).

Researchers want your help in mapping cities — and, more specifically, how cities are growing.

A team from Big Pixel Initiatives at UC San Diego is working with ASU and Columbia University. They plan to use crowdsourcing to tag land as either developed — or not developed.

One of those researchers is Geographer Ran Goldblatt. He’s a post-doc in the UC San Diego School of Global Policy and Strategy.