Detail of the documentation of toolmarks on the surface of the Ara Pacis Augustae during restoration in the 1980s.
On this image the process used by Peter Rockwell for documenting different toolmarks can be seen. The assistant here is colouring in a drawing of the relief with different colours symbolising different tools. Several of the drawings resulting from this study ended up being published in the volume edited by Eugenio La Rocca, 'Ara Pacis Augustae. In Occasione del Restauro della Fronte Orientale' (Rome, 1983).