With over 14 million people, half of which are squatters or slumdwellers, Mumbai is indeed a "maximum city" according to Schuyler Erle. The obstacles to constructing housing for Mumbai's huge homeless population pile up long before any plan is drawn: to submit a redevelopment project the area is required to be mapped, and before you can make a map you need reliable data.

Erle describes a daunting challenge to mapping Mumbai: the only data available consisted of many very detailed, but hand-drawn maps, which had been vectorized with no common geographical reference. One of the steps required to go from there to a complete geographical dataset, recounts Erle, involved people covering Mumbai using GPS devices to gather control points.

The help of the open source geodata community was also essential, as freely available software was used to rectify the vectorized data. Describing this project as resting solidly on the shoulders of volunteer help, or as he puts it, "long live free software", Erle refers to the process as "commons-based peer-production". Schuyler Erle rounds out his talk by recounting some of the particularities of working by distributed collaboration as applied to other geographic data projects, or any open source development project.