Computer Aided Classification of Ceramics

Usually a large amount of archaeological pottery is found at excavation sites. If one asks archaeologists what they use pottery for (or why excavated fragments of pottery are kept) they will probably reply "for dating evidence". Every fragment or pot holds the information about when, where, and for what it was made for. This fact places a heavy burden on excavators and primary processors or recorders of the material since the primary task of pottery research is comparison. This means that pottery must be grouped and recorded in a way that facilitates a comparison. In this study, a computer aided ceramics classification system will be developed, based on the experience made in a preceding project (Bildhafte Keramikerfassung, P9110-SPR) where the acquisition system was developed and tested. This proposal deals with the integration of the acquired data into a complete object description, which allows an objective classification due to shape features and object properties. The main technical goal of this project is to perform an automated classification and reconstruction of archaeological fragments by using the profile section of the oriented object and additional attributes (type of clay, dimensions, type of vessel and the site) belonging to the fragment. To automate this process, the profile has to be determined in the same way as in the manual documentation. In order to create the profile the 3-d information of the surface of the fragment has to determined. The result is a dense range image. Next, the profile has to be determined in the so-called orientation step. The term orientation describes the exact positioning of the fragment on the original vessel with the help of the axis of rotation. The thus generated profile is used to perform the reconstruction and retrieval of fragments of the same type. The profile is rotated by the original axis of rotation, thus measurements like volume can be estimated. Next a classification process tries to find different fragments belonging to the same vessel based on attributes stored in the archive database. After that, the profile of the fragment can be used to reconstruct the original (complete) vessel. This includes the possibility of reconstructing missing parts of the vessel and the search for possible matches of other fragments already stored in the archive with the one that is under consideration (part- assembly). The purpose of this project is the development of a technical tool that would help the archaeologist in the classification of ceramics. In this proposal a new approach to the classification will be introduced, based on already developed classification systems. Since classification is to be automated, algorithms for performing a classification that fulfil archaeological classification criteria have to be developed. From the archaeological point of view there are two major project aims: automated documentation and automated classification. The automated documentation of finds should bring about basic improvements in several areas. First of all it should result in documentation with a higher degree of objectivity. Drawings of the same vessel made by different draftsmen should not differ. In the preceding project the surface of fragments has already been achieved, now these preliminary results should be integrated into the automated documentation approach. Especially the automatic construction of profile sections and frontal views should be achieved. Whereas the results of the conventional acquisition by different archaeologists may differ, this system should serve the archaeologist as a powerful tool for reducing the amount of routine work and for getting an objective, reproducible acquisition of the material. Another aim of the proposed project (an automated classification of ceramic objects) should be combined with an automatic administration of finds (i.e. an archive database).