Establishing a national 3D standard compliant to CityGML: good practice of a national 3D SDI

This article describes a research project that realised a national standard for 3D geo-information. The standard was developed as part of a pilot in which more than 65 private, public and scientific organisations collaborated to analyse and push 3D developments in the Netherlands (run between March 2010 and June 2011). The 3D standard was established through several steps. Firstly a comparison between the existing 3D CAD and GIS standards was carried out that selected the OGC standard CityGML as the optimal 3D standard to align to. Secondly, the equivalent concepts in CityGML and the existing national standard for large scale topography (IMGeo) were identified. Thirdly IMGeo was extended to 3D following the principles of CityGML Application Domain Extensions (ADE). The model was tested by applying it to real data. Based on the experiences of this pilot, this paper proposes a framework of guidelines and principles for extending CityGML for national purposes, deduced from the modelling experiences. This is a unique contribution since experiences on extending CityGML are new and not well-described in the OGC CityGML specifications. Finally this paper presents the change requests which have been submitted to OGC to make the CityGML standard more suited for integration with existing 2D topographic information models. The change requests were formulated based on experiences from developing this nationwide 3D standard.