3D city models have many purposes ranging from urban planning, simulation, navigation systems, modeling, change detection, etc. They are in general used to visualize reality. The slums especially lie in the geographically (and otherwise) challenging areas and a 3D model could help with understanding some of the challenges people there face.
The idea was first presented to me by a friend, an architect Tomas Chapman, who runs a very interesting project in Johannesburg, South Africa, called Backdoors to the City (here’s an article which explains it well). He saw the building extraction that we did in Mathare and suggested that we build a 3D model. He explained me the basic principles and introduced me to Google SketchUp.
Another friend and architect April Hiebert liked the idea and decided to help work on it. She and her husband Dale Zak came to Mathare (Dale was at the time working for Ushahidi in Nairobi) to see the area and get a rough idea of how the place looks. We decided to estimate building and area heights from the satellite imagery, and complement this data with some basic measurements from the field. April then used Google SketchUp to draw the basic 3D model.
There’s still some work to be done on the model and I already have some ideas on how to use it further (I’m saving that for another blog post). In the meantime, below are some screenshots of the 3D model of Mathare.