Recognizing technique variation in rock engravings: ArchCUT3-D for micromorphological analysis

Ancient rock engravings evoke the interest of archeologists and art historians as an important remnant of human cultures. Traditionally, engraved images are studied based on iconography, iconology, and stylistic characteristics, with little emphasis on execution technology. In contrast, the research method presented in this study strives to characterize the techniques adopted for making rock engravings in ancient times, with technological variations considered as indicators of the engraver’s production process. 3-D scans of two ancient engravings and contemporary graffiti were obtained from Site 25 in Timna Park, Southern Israel. The models were analyzed with ArchCUT3-D, a software specifically developed to precisely evaluate the 3-D micromorphological characteristics of the incisions making up the engraving. The software analyzes the surface micromorphology by extracting 3-D slices of the incisions using an accurate and repeatable method. Our results indicate that different incisions were executed by remarkably distinct techniques of stroking the rock surface with a sharp tool. The identification of discriminant characteristics enabled us to demonstrate the particularities of the engraving operations, such as ergonomic conditions and the level of consistency of the engraving gesture. ArchCUT3-D thus provides a computational method for incision technique recognition through micromorphology specifications, and the reconstruction of engraving gestures and individual production procedures.