Detecting informal settlements via topological analysis
We outline methods for a) extracting the geometry of street blocks in urban centres using
OSM and remote sensing data, b) generating approximate cadastral maps of a
block given contained building footprints, and c) quantifying residents’ ability to navigate within
blocks through topological analysis of cadastral maps. This topological metric, termed “spatial
accessibility” and denoted k = 1, 2, 3, ..., determines whether areas of a city are informal
settlements, as blocks where k > 2 contain cadastral parcels without direct access to formal road
networks. We analysed 1 terabyte of OpenStreetMap data for 120 low and middle income (LMIC) countries.