Generating a 3D city model in LOD1 by extrusion, with the software 3dfier (github.com/tudelft3d/3dfier) developed by the 3D Geoinformation group at TU Delft (3d.bk.tudelft.nl) and partially funded by Kadaster. The software combines two data sources: a large scale topographic map (Basisregistratie Grootschalige Topografie - BGT), and a lidar point cloud (Actueel Hoogtebestand Nederland - AHN), resulting in a volumetric 3D model of the urban environment.