Built on a steep hillside in Rio de Janeiro is Rocinha, one of Brazil’s largest favelas. The sprawling settlement is home to 100,000 people, but government leaders had no accurate map of the city within a city—making it impossible to proactively plan for the future. MIT’s Senseable City Lab changed that, collaborating with Rio City Planning Commissioner Washington Fajardo and Brazilian tech company @brtech3d to develop a three-dimensional map. ⁠ ⁠ To document such a complex space, the team relied on LiDAR technology, which emits pulse light waves that bounce off object surfaces to measure distances and dimensions. The technology could gather more than 1 million data points per second. Yet team members knew they had to balance speed with thoughtful stakeholder communication, so they took the time to answer questions from curious residents about the project and technology. "We were entering their space,” says @senseable_city_lab director Carlo Ratti.⁠ ⁠ With data on everything from build...