added bootstrap buildings

README.md

@@ -38,6 +38,30 @@ docker compose restart api worker
 The API samples all `.tif`/`.tiff` files under `DEM_PATH` recursively. In Docker,
 the default `DEM_PATH=/data/dem` points to the mounted `./data/dem` directory.
 
+## Buildings Bootstrap
+
+Download an OSM PBF extract and import building polygons into PostGIS:
+
+```bash
+mkdir -p data/osm
+wget -O data/osm/northwestern-fed-district-latest.osm.pbf \
+  https://download.geofabrik.de/russia/northwestern-fed-district-latest.osm.pbf
+sh scripts/load_buildings.sh data/osm/northwestern-fed-district-latest.osm.pbf
+docker compose restart api worker
+```
+
+The import writes a `buildings` table with `geom`, `height_m`, `levels`,
+`building_type`, and `source`. Heights come from `height`, then
+`building:levels * 3.0`, then an estimated default by building type.
+
+Check the API:
+
+```bash
+curl -s -X POST http://localhost:8000/api/v1/buildings/query \
+  -H 'Content-Type: application/json' \
+  -d '{"bbox":[30.30,59.93,30.33,59.95]}' | jq '.features | length'
+```
+
 For local Python development:
 
 ```bash