We have completed the ground truthing of a test area of Mathare 10, Mashimoni, Mabatini and Thayu. The whole exercise took us two days. It took us one day to prepare – determine how to go about it, go out in the field to see how it works, what needs improving and to create proper forms which make sense. Then we divided the area into 11 smaller areas of focus for which we created detailed forms for data collection. By detailed forms I mean an A4 paper with a picture on top. Remember! It’s the execution that counts, he he…
We held a brief meeting on Wednesday, 16.2.2011, with all the Mathare mappers where we talked about the theories behind satellite imagery, building extraction, the importance of collecting such information and explained how the exercise will run in detail.
It took 5 groups 3 hours on Thursday, 17.2.2011, to check all the buildings in the test area, fix incorrect shapes of buildings, write down the types of buildings, and classify them. In other words, it took them 3 hours to ground truth 0.21 square kilometers which represents 7% of the whole Mathare area.
Through the exercise, we’ve encountered some problems which we need to address to AAAS for further clarification and advice. For example, how do we ground truth a big stone building which has tin houses on top of it? Is it one building or many (picture below in a circle)?
The next step is to digitize the data collected, send it back to the AAAS, and then wait.