Web based provisioning and application of large scale virtual 3D city models Virtual 3D city models represent and integrate a variety of spatial data and georeferenced data related to urban areas. With the help of improved remote sensing technology official 3D cadastral data open data or geodata crowdsourcing the quantity and availability of such data are constantly expanding and its quality is ever improving for many major cities and metropolitan regions. There are numerous fields of applications for such data including city planning and development environmental analysis and simulation disaster and risk management navigation systems and interactive city maps. The dissemination and the interactive use of virtual 3D city models represent key technical functionality required by nearly all corresponding systems services and applications. The size and complexity of virtual 3D city models their management their handling and especially their visualization represent challenging tasks. For example mobile applications can hardly handle these models due to their massive data volume and data ...