3 rd ISDE DIGITAL EARTH SUMMIT 12-14 June, 2010, Nessebar, Bulgaria INTERNET BASED DISTRIBUTION AND VISUALIZATION OF A 3D MODEL OF THE UNIVERSITY OF COLOGNE CAMPUS Willmes, C.*, Baaser, U., Volland, K. and G. Bareth Institute of Geography (GIS & RS), University of Cologne Albertus-Magnus-Platz, 50923 Cologne, Germany *corresponding author; Phone: +49-(0)221-470-6234, c.willmes@uni-koeln.de Abstract Visualization of 3D geodata integrated into a web browser based user interface is still a key issue in geoinformation science research. In a short overview of state of the art solutions for this demand, the key advantages and disadvantages of each of those solutions are lined out. As a solution which combines most of the advantages identified before, a CityGML based 3D model of the University of Cologne Campus and the setup of an OGC conform Web Perspective View Service for internet based visualization of this model is described. Keywords 3D geodata visualization, 3D model, 3D buildings, CityGML, 3D-SDI, WPVS. 0. INTRODUCTION In this paper an implementation of a CityGML (Kolbe et. al 2008) based 3D model of the University of Cologne Campus buildings and the setup of an OGC Web Perspective View Service (WPVS) based visualization of this model is presented. The considerations to choose the WPVS technique for the system setup and the implementation of this web service will be described in the following of this paper. Study area for this project is the University of Cologne Campus area for which a GIS is available, the CampusGIS (CampusGIS 2010). The CampusGIS provides general and spatial campus information, e. g. visualization, advanced search functions, orientation, routing and facility management. The overall design approach is based on the linkage of several existing relational databases with spatial data in a WebGIS environment (Baaser et. al. 2008). The University of Cologne, funded in 1388, is one of the largest and oldest universities in Germany. The most buildings of the university are located in a 2km² large area (the campus) in the western centre of the city of Cologne. 1. STATE OF THE ART The different available approaches to web based 3D geodata visualization have advantages and disadvantages. For a good user interface it is crucial to offer easy, fast and seamlessly integrated access to the visualization of the three dimensional geodata within the web browser user interface (Willmes 2009). This means, that the user should not have to obtain any additional software to what normally is present on an internet connected desktop computer, which is basically a state of the art web browser. The process of visualizing geodata in distributed environments can be generalized through the model of the OGC portrayal pipeline (Cuthbert 1998). The portrayal pipeline divides the process of geodata visualization into four independent steps, which must not be implemented on the same system. These four steps are: i.) Filter/Select, ii.) Display Element Generator, iii.) Render and iv.) Display. Figure 1 shows, that for the three dimensional case of geodata visualization, some specific constraints to the portrayal pipeline are to be considered (Altmaier & Kolbe 2003). In step i.) the data which will be visualized is selected by database, web service or file backend queries. In step ii.) a model of the data, which will be visualized, is generated with information of how the data will be styled/visualized by defined rules. For example the color of the non-textured parts of buildings, will be applied in this step. The format of these compiled models can be for example in CityGML, KML, VRML or X3D. In step iii.) those 3D models are rendered from the geometry and styling informations given in this scene graph models. In step iv.) the rendered view of the data is displayed on the client system (Willmes 2009). This partitioning of the visualization process allows the setup of distributed systems (Cuthbert 1998, Altmaier & Kolbe 2003). In the left illustration of figure 1, the different orchestration setups of the portrayal pipeline are shown. It shows, that it is possible to orchestrate data and display elements (scene graphs) from different sources, in 3D case it is not