The biggest slums in Nairobi (like Kibera and Mathare) usually consist of different villages. That is why before we started working in Mathare we had to determine where these villages are located.
This was/is important for many reasons:
For the purpose of determining the village boundaries we printed out the satellite imagery of Mathare, which was donated to us by the American Association for the Advancement of Science.
After that I gave the satellite imagery to Simon Kokoyo form COOPI and Reality Tested Youth Program. He walked around the slum and talked to elders, who helped him determine the village boundaries of the slum by drawing them on the printed satellite imagery.
I uploaded the satellite imagery into JOSM and digitized the boundaries according to the drawn image.