John Gait (1) (2), Katalin Bajnok (1) (3), Veronika Szilagyi (4), Imre Szenti (5), Akos Kukovecz (5), Zoltan Kis (4)
Archaeological and Anthropological Sciences. (17 November 2022). DOI: https://doi.org/10.1007/s12520-022-01688-y

Keywords

Pottery forming techniques, 3D imaging, quantitative orientation analysis, X-ray microtomography, neuron tomography, Monte Carlo simulations

Abstract

This article describes the quantitative analysis of the 3D orientation of objects (i.e. particles and voids) within pottery fabrics to differentiate two categories of pottery hand-building primary forming techniques, specifically percussion-building and coil-building, comparing the use of two independent non-destructive imaging modalities, X-ray microtomography (µ-CT) and neutron tomography (NT). For this purpose, series of experimental organic-tempered vessels and coil sections were analysed. For both imaging modalities, two separate systems were employed for quantitatively describing both the orientation of individual objects, as well as the collective preferential alignment of objects within samples, utilising respectively polar and azimuth angles within a spherical coordinate system, and projected sizes within a positive Cartesian coordinate system. While the former provided full descriptions of the orientations of objects within 3D space, the latter, through a ratio dubbed here the ‘Orientation Index’ (OI), gave a simple numerical value with which the investigated samples were differentiated according to forming technique. Both imaging modalities were able to differentiate between coil-built and percussion-built vessels with a high degree of confidence, with the strength of these findings additionally demonstrated through extensive statistical modelling using Monte Carlo simulations. Despite differences in resolution and differences in the attenuation of X-rays and neutrons, µ-CT and NT were shown to provide comparable results. The findings presented here broadly agree with earlier studies; however, the quantitative and three-dimensional nature of the results enables more subtle features to be identified, while additionally, in principle, the non-destructive nature of both imaging techniques facilitates such structural analysis without recourse to invasive sampling.

How Our Software Was Used

The datasets of segmented objects were analyzed in Dragonfly, which calculated various parameters for each object including voxel count, volume, polar angle, azimuth angle, minimum and maximum Cartesian coordinates, and 3D aspect ratio.

Author Affiliation

(1) Neutron Spectroscopy Department, Centre for Energy Research, ELKH, Budapest, Hungary
(2) Department of Scientific Research, The British Museum, London, UK
(3) Institute of Archaeological Sciences, Eötvös Loránd University, Budapest, Hungary
(4) Nuclear Analysis and Radiography Department, Centre for Energy Research, ELKH, Budapest, Hungary
(5) Department of Applied and Environmental Chemistry, Interdisciplinary Excellence Centre, University of Szeged, Szeged, Hungary