Preliminary comparison of close-range photogrammetric and microCT scanning: Surface Deviation Analysis of 3D digital models of hominin molar crowns

Document Type

Article

Publication Date

2-1-2023

Abstract

This study is a preliminary assessment of the viability of close-range photogrammetry in comparison to microCT scanning for the construction of 3D models of isolated molar crowns. Photogrammetric scanning is more cost-effective and less time-consuming than CT scanning, and in paleoanthropological contexts eliminates the possibility of exposing fossils to doses of radiation that affect ESR dating. Samples of fossil (Homo naledi), archaeological, and contemporary human molars were scanned via microCT and close-range photogrammetric scanning. The photogrammetric scans included 96 digital images per tooth and the resulting models were compared to their corresponding CT models using point-to-point Surface Deviation Analysis. The surface difference between the CT mesh models before and after processing functions such as smoothing and retriangulation was also assessed. Signed-rank tests comparing the surface difference between the two sets of mesh pairs show no significant difference in the level of deviation within the archaeological and contemporary molar samples. The Dinaledi sample demonstrates complementary results, as the majority of the photogrammetric meshes fall within a devised acceptable range of difference when compared to the processed CT meshes. A total of 81% of specimens in the study with suitable characteristics—a stained and unreflective crown surface—provided photogrammetric meshes that fell into this devised range. Crown characteristics that produced unsuitable models had unstained and reflective surfaces. Areas of higher deviation tend to occur in crenulations and fissures. The exploratory results suggest that sufficient reflectance and color contrast data must be present on the tooth enamel to create viable photogrammetric surface models, however further study is needed to fully understand the capabilities and limitations of close-range photogrammetry in comparison to microCT scanning.

Publication Source (Journal or Book title)

Journal of Archaeological Science: Reports

Number

452

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