INVESTIGATION ON TRADITIONAL AND MODERN CERAMIC DOCUMENTATION Martin Kampel, Hubert Mara and R. Sablatnig Vienna University of Technology Pattern Recognition and Image Processing Group Institute of Computer Aided Automation Favoritenstrae 9/1832 A-1040 Vienna, Austria {kampel,mara,sab}@prip.tuwien.ac.at ABSTRACT Archaeology is at a point where it can beneﬁt greatly from the application of computer vision methods, and in turn provides a large number of new, challenging and inter- esting conceptual problems and data for computer science. This is true in particular in the study of ceramics - the most abundant and widespread of all archaeological ﬁnds. The traditional way of documenting archaeological sherds is to draw the proﬁle line, which is the intersection of a sherd along the axis of symmetry. A proﬁlograph is a mechanical device, which can directly acquire and transfer a proﬁle line by pin-pointing the proﬁle on a sherd to a computer. We developed a fully automated vision system, which is able to compute the proﬁle line out of the acquired 3D model of the fragment. In this paper we want to give a thorough comparison between the traditional manual approach, the proﬁlograph and our system and present an improvement of the robustness of our approach by ﬁnding circular rills on the fragments. Practical experiments have been undertaken at the excavation Tel Dor in Israel. 1. INTRODUCTION Fragments of pottery, called sherds, are among the most widespread archaeological ﬁnding. Archaeologists there- fore ﬁnd tens of thousands of sherds per month on an ar- chaeological excavation site. The documentation, classiﬁ- cation and publication of these ﬁnds is an important task for archaeologists [5], because these sherds represent infor- mation about cultural groups, population movements, inter- regional contacts, production contexts, and technical or func- tional constraints [3]. The traditional method of documentation of an archae- ological sherd is a drawing of the proﬁle line, which is an intersection of the sherds along the axis of symmetry (also called rotational axis). The proﬁle of the fragment is mea- sured using a so-called proﬁle-comb. This comb consists of several movable metal pins that adjust themselves to the surface of the object if pressed on it as shown in Figure 1. The accuracy of this comb is 1mm since this is the distance between two consecutive pins. The proﬁle comb is applied to the front and the back of the fragment, the correct thick- ness is determined by measuring the thickness at the top (ideally the rim) and the bottom of the fragment (in respect to the rotational axis) with the help of a caliber. Finding this axis of rotation and drawing the proﬁle line by hand re- quires expert knowledge and a certain amount of time. It is therefore an impossible task to draw all the proﬁles of such a high number of sherds. Another disadvantage is that the hand drawing is dependent on the skill of the draftsperson. It is also very time consuming to manually compare several hundreds of proﬁle lines found in publications. Fig. 1. Measuring the proﬁle with a proﬁle-comb [5] The proﬁlograph is a mechanical interface device, which can directly acquire and transfer a proﬁle by pin-pointing the proﬁle on a sherd to a computer. One disadvantage of this procedure is, that the axis of symmetry still has to be found manually and also the time for acquisition of a proﬁle line requires approximately the same amount of time as the manual drawing. Our group has developed a fully automated system for acquisition and documentation of archaeological fragments based on proﬁle lines. It uses a 3D-Scanner based on struc- tured light, described in [7]. We assume archaeological pottery to be rotationally symmetric since it was made on a rotation plate. The 3D-Scanner used was a Minolta VIVID- 0-7803-9134-9/05/$20.00 ©2005 IEEE