One of the greatest challenges for the socio-spatial integration of informal settlements to the “formal” urban fabric, equipped with basic infrastructures and services, is the critical lack of data on the populations and the built environments of those settlements, with sufficient spatial-temporal resolution. In order to respond to this urgent demand for more information on informal settlements, we propose a method based on new geo-spatial technologies to collect and analyse data. This method can be associated to what some authors have named Participatory Geographic Information Systems (PGIS), as it is founded on the collective action of volunteers and local community dwellers that appropriate cartography tools to display their own perceptions of the built environment.