Orientation of Fragments of Rotationally Symmetrical 3D-Shapes for Archaeological Documentation

Motivated by the requirements of modern archaeologists, we are developing a documentation system based on structured light for acquisition of ceramics. Fragments of ceramics are daily finds at excavations and important for archaeological research, because their shape leads to information about ancient cultures. The shapes used for documentation are called profile lines and estimated by a vertical cross-section of orientated fragments. As ceramics have been produced using rotational plates for several thousands of years, the rotational axis can be used for orientation. Therefore we conducted experiments using existing methods for estimation of the rotational axis. The drawbacks of these methods are the requirement of either complete objects or industrialized quality of symmetry. Therefore we show a new method using circle templates, which has been inspired by the manual method of archaeologists. In this work we present results using previous and related work in comparison with the estimation of the rotational axis using circle templates. The results of the presented methods are shown for synthetic data, well-known fragments and real data acquired at an archaeological excavation. Finally a conclusion and an outlook is given.