“Using Image Analysis Software to Correlate Sherd Scans in the Field and X-Ray Element Maps in the Laboratory,”
Society for Archaeological Science Bulletin 31.2, pp. 8-12.
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This paper offers an overview on techniques applied at Urkesh for the analysis of the ceramic tradition.
After a brief presentation of the site, it is stressed the huge amount of sherds recovered from the mound: each season yielded around 40,000-60,000 pottery sherds and many complete vessels (>1000 per season). All this overall material is available to any scholar through the UGR webpage about Urkesh Ceramic Typology (where descriptive statistics of ceramic assemblages can be found).
The research problem is stated: “To assess chronological and stylistic variations in clay choice, tempering materials, and firing techniques” (p. 8). To fulfil this purpose, the archaeologists applied petrographic examinations on both the surface and the section of the sherds: the analysis approach involved the use of X-ray microanalysis and element mapping (XRF).
The sherds, after having been cut on site (with a LEZACO marble cutter), were washed carefully and then scanned at a high resolution (2400 dpi). Afterwards, a image-analysis software (Colormod) “was used to identify different areas in the flatbed-scanner images on the basis of the pixels' colors. Cluster of pixels that fall within the same color range area grouped in a scale of grays, and their area coverage is tabulated” (p. 9).
Further procedures are applied to 'calibrate' the data obtained from the analysis. Herewith, the basic results: “1) chronological variation in the composition of the calcite-tempered wares [...]; 2) clearer distinctions among broadly related but distinctive wares [...]; 3) insights into the manufacturing, finishing and firing processes [...]; 4) understanding the fourth-millennium Late Chalcolithic wares”.
[M. De Pietri – November 2019]