3D Morphometrics of Coil-Built Ceramics: Quantifying Deviation from Rotational Symmetry

Using Geomagic Verify, we were able to calculate not only the whole deviation (between the symmetrical [nominal] surface and mesh [scan] data), but deviations for each of the 12 sections that we are using in our analysis of morphometrics, as well as deviations from landmark/semi-landmark locations.

Location of sections used in our analyses of morphometrics and symmetry (click to enlarge).

Section 1 (of 12) from the illustration above.

We were also able to calculate deviations between the point data and the nominal surface, giving us a method by which to view the deviation from rotational symmetry for each landmark/semi-landmark. These data were subsequently exported from Verify to R, allowing us to explore abnormalities in vessel symmetry that may help to further discriminate between–potential–individual/groups of makers.

Deviation between L/sL data points and nominal surface using a ±0,5mm tolerance (green).

Understanding where this variation occurs among the landmark data could also prove useful once we begin to move past our current consensus configuration, and into configurations aimed at quantifying the shape variation in and among the various groups of ceramics. It may also be the case that these data can help us to identify something of a transitional species (for lack of a better term), further highlighting the when and where that the evolution of specific elements of ceramic vessel shape may be said to have occurred.

This is our final post of 2014.  We’ll see you right back here in 2015. From all of us here at the Center, have a wonderful holiday!

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Written by zselden

Selden (PhD, Texas A&M University, 2013) is a US Marine Corps veteran, cyclist, kayaker, backpacker, hiker, climber, fisherman and general all-around outdoor enthusiast. His research is focused at the confluence of archaeological methods and digital technology, and he is particularly interested in the application of 3D technologies to archaeological problems, geometric morphometrics, network analyses, predictive modeling, archaeological theory, and archaeological science.