Building extraction of Mathare No10, Mashimoni, Mabatini and Thayu

Although the Ground Truthing of the shapefile which was sent to us by AAAS was done in three days (read more here and here), fixing the shapefile itself took a bit longer. In the process, we created three shapefiles.

The main shapefile contained the closest resemblance to the situation on the ground. Our teams have checked and corrected on the ground the shapes of most of the buildings, written down the types of the buildings, and classified them. From this exercise, 4 attributes were added:

a) Type means the type of building, which is either Brick, Corrugated Iron Sheet, or Wood Stalls

b) Name is name of the building (if it has a name)

Type of buildings

c) Designated is the designated use of the building, describing what the building is used for. It can be many things, including: school, house, business (like bar, cyber cafe, garage, hardware shop, market place, etc.), church, toilet, etc.

Designated use of the buildings

d) Action is what kind of action was carried out on the shape of the building – there are two options: 1) Added if the building was missing and was added and 2) Modified if the building was either moved, merged, or in any other was modified

Action performed

Many times in the slums you see corrugated iron sheet houses build on top of brick houses. We’ve identified these structures in the second shapefile called Buildings On Top.

Corrugated iron sheet buildings on top of brick buildings

The third shapefile contains deleted shapes (buildings) because they are either not there, are incorrect (there are many shapes representing one building), or don’t represent permanent structures (like temporary tents in the Chief’s camp).

Deleted objects

Our teams have collected around 750 points in the first run of data collection and are now it the second phase of detailed Water and Sanitation data collection. The idea is to eventually attach the points they collect to building extraction for the whole of Mathare.

Attaching points to buildings

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~ by mappingnobigdeal on March 26, 2011.

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