CityGML Implementation Specifications for a Countrywide 3D Data Set

This paper discusses and presents the specifications of a countrywide 3D data set for The Netherlands and the best practices to generate 3D data accordingly. The specifications extend the OGC 3D standard CityGML to align it to national requirements. Although CityGML offers a solid base for 3D information modeling, we have met the problems of CityGML being a generic standard resulting in too much flexibility and in some cases ambiguity when implementing it at a national level. Based on experiences and use cases, we refined and extended the CityGML specifications into implementation specifications for our Dutch context. We present a workflow to generate 3D information compliant with specifications, starting from existing 2D/3D raw data. Also, a 3D validation tool has been developed to be able to evaluate 3D information against the defined specifications. Currently these specifications have been offered to OGC as best practices.