Students of the department of civil engineering of the University of Dortmund constructed with the help of a CAD tool in their class "making the invisible visible" a comprehensive spacial computer model of "Colonia Ulpia Traiana", an ancient Roman settlement which was located near the city Xanten.

In cooperation with architects, civil engineneers and archeologists and computer scientists a model was created with different levels. The first level shows the entire complex from a city planning perspective with an abstractly modeled environment. In the next level the most important architectural objects (e.g. forums, thermal spas, temples, amphitheatre) are visible. On the third level individual interiors were reconstructed as well as technical details e.g of the thermal spas are visualized. The entire reconstruction is based on archeologial digs and historical sources.

This computer model is embedded in a multimedia environment at the University of Dortmund. The system is at first an interactive guide through the city of Xanten where text and photos of the digs are connected to photorealistic representations of the CAD model like blueprints and different views of detail drawings. A first version of this guide is accessible through the internet.

As part of a research project this existing model is supposed to be integrated with a multimedia system which can be put to use on location. In addition, audio information, more background knowledge via Internet link to worldwide accessible data as well as video sequences of walks through virtual cities or individual buildings will be integrated. If the computing power of the hardware suffices the user can do a virtual walk through the city online.

The GMD (German National Research Center for Information Technology) in Sankt Augustin (near Bonn) will adapt part of the 3D model and visualize it on the Responsive Workbench. In addition, a special interface will be developed which will enable the visitor to fly through the city like on a flying carpet. The "Virtual Balance" can be controled through body balancing.

The most interesting feature for the visitor of the archeological park is to see through photorealistic representations what this place used to be like. Hence the visitor will gain a new understanding of the archeological findings which are ususally most difficult to interprete.

The seminar of the University of Dortmund and their scientific work is supported by The Archeological Park Xanten in the Landscape Society Rheinland and the Nemetschek Programm GmbH, Munich. The GMD will add the online operations as well as the man-machine interface to the project.