Marc Pollefeys, Belgium | ISBN: | Submitted: Jun 30, 1998

Virtualizing Archaeological Sites

Nowadays many archaeological sites are being reconstructed on graphical workstations. This work is done based on measurements obtained through a variety of 3D measurement techniques. These VR models then allow virtual visits.

One of the disadvantages of the actual techniques is that the whole site has to be rebuild manually with a modeling package. This requires a lot of time. In addition it is difficult to model complex shapes and to take all the details into account. Obtaining good texture maps is also a critical issue.

An alternative approach consists of using images of the site. We have developed a system which can automatically reconstruct textured 3D models from image sequences of a site. The advantage is that the reconstruction is much closer to reality, one could speak of virtualized reality. This technique offers a great deal of flexibility since it can work with a simple video- or photocamera. Additionally, zoom and focus can be varied freely during the acquisition.

An important advantage is that details like missing stones, not perfectly planar walls or symmetric structures are preserved. In addition the surface texture is directly extracted from the images. This does not only result in a much higher degree of realism, but is also important for the authenticity of the reconstruction. Therefore the reconstructions obtained with this system can also be used as a scale model on which measurements can be carried out or as a tool for planning restorations.

Another important advantage of this system is that it is independent of object scale. The only difference is the distance needed between two camera poses. Therefore the technique can be used to generate reconstructions of a site at different scales, going from a global reconstruction of the whole site to a detailed reconstruction for every monument. These reconstructions thus naturally fill in the different levels of details which should be provided for optimal rendering. Note that it is straightforward to extract a digital terrain map or orthophotos from the global reconstruction of the site.

The potential of our technique will be illustrated through 3D models of the archaeological site of Sagalassos in Turkey. Partial VR models of several monuments of the site were acquired with our system. A model of the whole site was also generated with the same system. The complexity and the level of detail that can be reached through the system is illustrated through a VR model of a highly decorated part of a Jain temple in Ranakpur (India).

Since these reconstructions are almost completely automatic and the on-site acquisition time is very short, many new applications come to mind. For example almost every stone of a ruine could be reconstructed separately, allowing for a virtual reconstruction of the ruin before a real reconstruction is attempted.

[more information]

[other authors]
Reinhard Koch, Maarten Vergauwen, Luc Van Gool

[keywords]
VR models, generating 3D models, Digital Terrain Map, Archeology, World Heritage, Sagalassos (Turkey), Ranakpur (india)