Jiang Yu Zheng, Japan | ISBN: | Submitted: Jun 23, 1998

Digitizing and Virtual Recovering Excavated Relics at A World Heritage Site

This work aims at a virtual recovery of excavated archaeological finds in cyberspace for ancient relic preservation, archaeology research, and multimedia material generation. Many excavated pottery artifacts have already suffered from a certain degree of damage when they are discovered. Archaeologists have to spend much time in restoring broken pieces before an unearthed object can be displayed to audiences. This work introduces a new application of computer vision, graphics and virtual reality in archaeology. First, we develop an imaging device to digitize damaged pieces in the form of 3D shape and surface texture. Then we build an interface for connecting broken fragments in a virtual space so that the original model can be visually recovered. The idea of virtual recovery provides a new opportunity and flexibility for archaeologists to examine complex relics. Moreover, the virtually recovered objects can be directly displayed in a multimedia format, e.g., a virtual museum accessed via internet or with a CD-ROM. The effort has been carried out for a UNESCO registered world heritage at Xi(IU(Jan, China.

For thousands years sleeping in ancient tombs and ruins, archaeological finds have suffered from a certain degree of damage when they are excavated. Many of them are arts and artifacts with high archaeological and culture value. Recovery of these elaborated objects to a certain degree is of significance for understanding different culture and early civilization. It is also an important step towards the display and exhibition of relics using the latest developed multimedia technology. In excavation and recovery processes, a wealth of knowledge and experiences are required. A tremendous manpower has to be employed as well. An archaeologist needs to search damaged pieces, imagine the original shape, and connect fragments to return their appearances in past times. The ancient remains can be clay, terra cotta, china, metal, wood, textile, etc. To restore a broken china, for example, an archaeologist needs to inspect shape and boundary of each piece, predict the original appearance, and test consistency of each pair of pieces. Being supported by some special frame, those pieces are usually placed in a 3D space for augmenting spatial imagination in the reconstruction. Finally, those fixed pieces are glued together, which is almost irreversible and requires full confidence in correctness. Many discovered fragments such as those from a statue might be very heavy and assembly of them is a hard work. One can imagine how difficult it would be to play such a 3D jigsaw puzzle with some incomplete and lost pieces. The difficulties archaeologists normally face in the recovery process are: 1. ambiguity in determining fragments combinations, 2. weight of fragments in a free assembling test by trial and error, 3. irreversibility after fragments are adhered in the recovery. At the same time, an unearthed relic may have lost its original pigment painted on its surface. It would be of great interests for archaeologists to reproduce the faded or dropped ancient color. This project aims at assisting recovery of unearthed objects and solving above problems by using image processing, graphics, and virtual reality technologies. The progresses in these areas provide powerful tools to archaeology research. We consider three objectives in the computer-aid excavation as follows: 1. Digitizing excavated finds: imaging and registering discovered pieces and their relations in excavation sites for database construction. A laser range finder is developed to measure the 3D shape and surface color of excavated objects. 2. Virtual Recovery: recovering damaged finds in a graphics generated virtual space for guiding adherence of real pieces. An interface is developed for flexible manipulation of graphics objects; 3D aspect views of a figure or 3D models of different pieces are combined to produce a complete model. Faded colors of objects are also recovered by rendering the remaining color samples to the object surfaces where the ancient pigments have dropped. 3. Virtual Exhibition: producing multimedia sources from the recovered objects for display either in a virtual museum accessed on internet or on a video kiosk at an excavation site. The excavated artifacts hence can be reserved for exhibition in their unearthed states. The advantages of such new concepts lie in the following. 1. The measured 3D shapes of unearthed relics are in a fadeless digital format. The excavated finds can remain as fragments, which is good for preservation and archaeology study even in the next generation. 2. Virtual recovery is a non-adhesive and repeatable process which can prevent fragments from miss-connecting. It is also carried out in a weightless space. Without moving real heavy fragments, an archaeologist will be able to manipulate fragments on a computer, i.e., planning reconstruction by using mouse and other position sensors. 3. Virtual exhibits can be produced directly in forms of image and 3D graphics model. The recovery of real damaged relics may be omitted. This may even change the conventional exhibition style. In this paper, we will focus on the topics of 3D measurement of excavated objects, construction of virtual space, and several functions of a designed interface for virtual recovery. We are doing experiments at a world famous excavation site ---- The Museum of Terra-Cotta Warriors and Horses in Xian, China.

[more information]

[other authors]
Zhong Li ZHANG, Norihiro ABE

[keywords]
virtual recovery, virtual reality, 3D modeling, 3D measurement, multimedia, interface, color rendering, excavation