Geometric Morphometrics and a 3D Caddo Vessel from the Sam Kaufman Site at SMU

While yes, this post contains a great interactive figure of an incredible Caddo vessel from the Sam Kaufman site (curated at Southern Methodist University #SMU), I wanted to take a moment to bring us full-circle, and return to the reason that I am scanning all of these vessels. Some time ago, I began getting fascinated by the high degree of variability in Caddo vessel shape and size, and have since also noticed some degree of variation in asymmetry.

At the same time that my interest in this topic began to increase, I also quickly realized just how much room for growth that there was in terms of applying geometric morphometrics to archaeological problems. It took time to get through the literature; and I kept finding new articles and book chapters listed in the references of my readings that had escaped the reach of my initial literature review.

Since I had been tinkering with social networking, I reached out to a colleague to assist me in building a citation network. That network has since been completed, and proved to be an invaluable asset in terms of not only centralizing the archaeological literature associated with geometric morphometrics, but it helped me to identify those works in the geometric morphometric literature that are most often cited (InDegree) and most important (identified using Google’s PageRank algorithm) to the overall network (click here to view the interactive network).

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Directed bipartite citation network for studies of geometric morphometrics in archaeology.

Having made my way through the literature, I began to think through the various methods of landmark and semilandmark applications that were available (based on the numerous research questions that could be asked of these data), and quickly found that the configurations were really only limited by my 3D modeling abilities. At that point, I ventured up to Lakewood, Colorado to spend some time working with the crew at Geomagic, where I learned how to use and employ the various features of Geomagic Design X and Control X (more here). Using these tools, I was able to devise a method of applying landmarks in a replicable manner using reference geometry that was built around the 3D mesh of the ceramic vessel. This first iteration of the landmark and semilandmark configuration worked very well for addressing some of my initial questions (see that in the video below).

From here, things began to get more complex. In October of last year, I headed to Portugal for what would be an important transitional period for my work; learning how to write scripts for, and run the various analyses in, the geomorph package in R. This opened something of a Pandora’s box for me, from which it is very likely that I will never fully recover. Needless to say, shape, form, allometry and asymmetry shifted quickly from a peripheral interest to something of a primary project.

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Procrustes superimposition of landmarks and sliding adaptive semilandmarks used in the analysis of Caddo ceramics.

Since then, there have been dozens of iterations and developments in my landmark and semi-landmark configurations and analyses; many of which (particularly those associated with my morphological integration inquiries) are actively evolving. I was fortunate to receive funding for much of this work through the National Center for Preservation Technology and Training (NCPTT); a group that I have really enjoyed collaborating with.

As you interact with this vessel from the Sam Kaufman site, consider where (and how) you would apply landmarks/semi-landmarks to the 3D surface.

In terms of theory, analyses of geometric morphometrics can be couched within several interesting anthropological lines of inquiry that include, but are not limited to, (1) identifying the locus of a specific innovation, (2) the spatial and temporal dynamics of morphological variation for specific elements (neck, body, base, etc.) of ceramic design, (3) identifying or refining social networks used by specific Caddo polities/groups during temporal periods previously defined—primarily—through design-based seriations, (4) intra/inter-polity/group variation of shape, form, allometry and asymmetry for ceramic design, (5) potential trade relationships based upon the presence of a specific shape/form of vessel outside of known (assumed) social boundaries, and (6) the power or influence that shifted among and between polities through time. These considerations could be woven into discussions of communities of practice, craft specialization, ceramic technological organization, politics, religion, and—possibly—inter/intra-polity disputes and warfare. Furthermore, this research design has the capacity to inform greatly upon the evolution of ceramic design as it relates to the shape, form, allometry and asymmetry that occurs in Caddo vessels, and by adding the related qualitative measures to our results we might just have the potential to bolster evidence for human behaviors associated with ceramic production and use within the larger ancestral Caddo territory.

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Historic era (1680+) Caddo networks based upon ceramic types (as I tip my hat to Dr. Timothy K. Perttula). Incorporating elements of vessel shape, form, allometry and asymmetry may help us to further refine this current iteration of the Historic Caddo network.

Initially a development in the biological sciences, the study of geometric morphometrics in archaeology will no doubt include some interesting discussions regarding the various analytical and theoretical components that are most appropriate for a cultural system versus a biological system as we continue to press forward. There remains plenty of thinking left to do on this subject, but based upon the preliminary results, the capacity for geometric morphometrics to inform upon issues related to material culture and cultural systems could be enormous.

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The very humble beginnings of exploring directional and fluctuating asymmetry in Caddo vessels.

Beyond the realm of empirical geometric morphometric studies, lies the domain of theoretical morphospace. Biologists have gainfully used theoretical morphospace to aid in clarifying issues of morphological change through time. They have done so by aggregating the results of geometric morphometric studies–a dialogue which would seemingly fit very well within the scope of anthropological and archaeological inquiry. By definition, theoretical morphospace represents the full range of possible morphologies for a group of artifacts; allowing investigators to posit, and contemplate, more- and less-adaptive morphologies (similarities and differences). It is within discussions of theoretical morphological transitions where I see the greatest promise for geometric morphometrics in archaeology; an ambit of inquiry in which the skeleton trees and topological properties of the artifacts tell us a much more dynamic story with regard to the progression of a particular shape (bottle, bowl, olla, etc.) through time. Within the context of my own long-term research design, theoretical morphospace seemingly holds much promise, and may represent the approach needed to identify, unlock and unpack a ceramic morphological transition that remains hidden in the various vessel shapes once employed by Caddo potters.

So, while the 3D images are fun to interact with–and have any number of preservation, access and outreach perks–my intention is to use them to bolster our discussions of shape, form, allometry and asymmetry in Caddo ceramic studies, and to use that evidence to posit a number of novel insights into the highly variable and dynamic prehistoric landscape that the Caddo people once commanded.

Many thanks to the Caddo Nation of Oklahoma and Southern Methodist University (Dr. Sunday Eiselt in particular) for the requisite permissions and access needed to scan this important artifact from the ancestral Caddo territory, and to present the 3D model here in color.

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3D Scanning Workshop at SMU

I recently visited the Department of Anthropology at SMU to teach a 3D scanning workshop. The repository is host to some very important Caddo vessels from the Sam Kaufman (or Roitsch) site, so we (working with Dr. Sunday Eiselt and her students) documented the vessels in 3D. We thought that this would be a great opportunity for her undergraduate and graduate students to get some hands-on experience with a wide range of scanners, and it worked out very well (more here).

In addition to the 3D documentation, we collected high-resolution photos for each vessel with a standard suite of qualitative attributes (temper, firing core, decorative motif, etc.). These data will augment the results of the upcoming asymmetry and geometric morphometric analyses.

(this is a 3D figure-activate it by clicking on the “play” button, then click/drag to rotate)

Dr. Eiselt’s students caught on quickly (more here), and were soon learning how to edit and process their own scans. While I had previously scanned a few of the vessels, I used the workshop to test a new project-driven workflow that ended up working better for the students. In the image below, you can see one of Dr. Eiselt’s students scanning a vessel with the Creaform scanner, there is an active scan running with the Konica-Minolta Vivid 9i in the light box, and another scanner (NextEngineHD) running on the other side. We also worked through some of the same vessels with the ZScanner700CX.

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By the end of the first day, everyone had the basics. On the second day, a selected group of students worked through a set of standard post-processing protocols for scans generated the day before (and a few surprise anomalies that I brought with me). In this exercise, we learned why some scanning strategies work better than others, and why it is important to know that information before starting a new scanning project. We spent some extra time with the NextEngineHD, since they are hoping to purchase one for the lab at SMU.

In addition to the laser scanners, we also learned how to make 3D models using 123D Catch, the free photogrammetry software provided by Autodesk, of Woodmen of the World headstones at a local cemetery. I look forward to seeing some of their new models posted in the near future (see their first model of a headstone here).

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Feature by 3D Systems

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 To read this and other Success Stories from 3D Systems, click here. To view the original release of this industry publication, click here.

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robert z selden jr, archaeology, archeology, geometric morphometric, ceramic, analysis, mathematics, statistics, 3d, 3d scan

On Missing Data: 3D Morphometrics of Ceramic Artifacts

In the sample of complete and reconstructed Caddo NAGPRA vessels from the Turner Collection, many were found to include missing data (most often from sherds that were never recovered). While we have not been scanning vessels with large amounts of missing data–must be very close to complete–we needed to test the various methods by which those missing data can be reconstructed. Further, we wanted to explore the deviation of the results from the original mesh.

To do this, we used a whole/intact vessel from the Ellis Collection, cut a hole in the mesh, then used one of three functions in Geomagic Design X (defeature, fill holes, and edit boundaries) to generate new data over that area. Shifting over to Geomagic Verify, we use the original mesh as the nominal data, and the scan with missing data as the scan data to calculate the deviation between the two.

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Results from the edit boundaries function.

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Results from the fill holes function.

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Results from the defeature function.

In this case, the defeature function resulted in the lowest deviation from the original surface; however, this is not always the case. Each of the three functions was found to be successful in addressing missing data, and all warrant exploration on areas of the vessel that are geometrically similar to that where the missing data occurs to identify which function works best in each individual case. Additionally, the results of these comparisons should augment any publication as supplementary data.

My work with geometric morphometrics employs landmarks and sliding adaptive semilandmarks along a spline to compare various aspects of vessel shape, and selecting the correct function to address missing data in a sample could potentially impact those results. Through making an informed decision regarding which function to implement, we are mitigating a–potentially–higher degree of error within our sample.

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Article Published in Advances in Archaeological Practice

The article was recently published in the current edition of Advances in Archaeological Practice, and is focused upon the documentation and analysis of Caddo NAGPRA vessels from the Vanderpool site in East Texas. This effort was the pilot study for a much larger/broader study of Caddo ceramic vessels that will begin later this summer. We are very grateful for the comments and constructive criticisms that developed in our discussion of this project, and hope that you enjoy the article.

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The article is available for download on the Advances in Archaeological Practice website (here), and in our institutional repository (here).

A special thanks to Mr. Robert Cast of the Caddo Nation of Oklahoma and Mrs. Patti Haskins and the Gregg County Historical Museum for allowing access to this collection of NAGPRA vessels.

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