The digital cathedral of Siena - Innovative concepts for interactive and immersive presentation of cultural heritage sites

In this paper, innovative technologies for the presentation of complex cultural heritage sites with immersive 3D computer graphics are introduced, wich are based on new concepts, partly having been adopted from other computer graphics areas to the specific needs for cultural heritage presentations, partly having been developed especially for this purpose. The main focus of this project was to develop new concepts for the integration of historical, architectural and cultural data related to a cuöltural heritage site, into an immersive Virtual REality (VR) Environment suited for presentation of the digital model. These concepts include digital storytelling, virtual 3D avatars and 3D agents. The 3D avatar was implemented as a virtual tourist guide, who accompanies the visitors on their tour and shows them the places of interest. Futhermore, specifics of the very detailed and complex digital models of cultural heritage sites are adressed, in order to meet the high quality requirements of an interactive 3D visualization. Special focus has been put on both the frame rate and the visual quality. Beside Level-of-detail mechanisms, texture-paging techniques have been developed to allow the use of very high resolution textures. Lichting simulation based on radiosity simulation, which ensure a high visual quality, have been extended for the efficient simulation of global illumination effects within very complex models. These new concepts and techniques have been successfully applied in the immersive VR presentation of a digital model of the cathedral of Siena, which has been shown to the public during the EXPO 2000 in Hannover.