# Building geometry API

## **Dataset**

The building geometry dataset ([**3D BAG**](https://docs.3dbag.nl/en/)) is an up-to-date dataset containing 3D building models of the Netherlands. It contains 3D models at multiple levels of detail ([**LOD**](https://docs.3dbag.nl/en/schema/layers/)), which are generated by combining two open data sets: the building data from the [**BAG**](https://docs.3dbag.nl/en/overview/sources/#BAG) and the height data from the [**AHN**](https://docs.3dbag.nl/en/overview/sources/#AHN). 

There are data attributes describing a building: the number of floors and the area but also information about the surfaces of a building: surface type, area, perimeter, geometry. The goal of the Building geometry API is to expose this information to be able to fetch the geometry data of a single object.

## Use case

* Use building geometry data in the addition to the Sustainability API for improved calculations
* Retrieve roof surface area's, its orientation and sloping
* Extract the orientation of the walls and its (shared) wallsurfaces
* Extract the object polygons in GeoJSON format