As I’m not yet sure what will be included in the alpha version of the damn project, I’m getting inspired. This time by Tanga Building Footprints Import announced on the imports mailing list.
It looks like the buildings are already imported in the Tanga city, e.g. this one, but I’ve never done the import thing, so I can’t say.
In this diary, I’m going to introduce the example mapping workflow with the prepared data based on Tanga Building Footptrints Import using the damn project. Not everything is yet fully automated, so this diary is more like describing the proof of concept. However, I’m open to the needs of the future.
Create area
There is the dataset of the buildings available on the wiki page. I like
that idea of huge GeoJSON file that includes the features with the corresponding
geometries. As I’m not the import guy, I’m confused with _key_s in the
properties (I mean these underscores of each key.) I need only building:yes
tag, so I’ve renamed just those (note that notepad’s “Replace All” would do the
same:)
sed -i 's/_building_/building/' buildings.geojson
I’ll create new area to work on. Therefore, I need the geometry of the whole
area, where the buildings are. For that, I’ll use the damn-client.py
scripts. (The shapely must be installed.)
cd damn-client.py
./convex_hull.py buildings.geojson > ch-buildings.geojson
The command took about a minute on my laptop. The ch-buildings.geojson can be
used as the GeoJSON boundary file in the damn project’s manager.
Buildings of the squares
So I’ve area to work on divided to squares. Now, I need the GeoJSON files containing all the buildings of each square. I’ll use the damn-client.py scripts once again:
cd damn-client.py
./prepare_tmp.py https://server.damn-project.org 2351 buildings.geojson

