Assessing 3d Photogrammetry Techniques in Craniometrics

Abstract

ABSTRACT:Morphometrics (the measurement of morphological features) has been revolutionized by the creation of new techniques to study how organismal shape co-varies with several factors such as ecophenotypy. Ecophenotypy refers to the divergence of phenotypes due to developmental changes induced by local environmental conditions, producing distinct ecophenotypes. None of the techniques hitherto utilized could explicitly address organismal shape in a complete biological form, i.e. threedimensionally. This study investigates the use of the commercial software, Photomodeler Scanner® (PMSc®) threedimensional (3D) modelling software to produce accurate and high-resolution 3D models. Henceforth, the modelling of Subantarctic fur seal (Arctocephalus tropicalis) and Antarctic fur seal (Arctocephalus gazella) skulls which could allow for 3D measurements. Using this method, sixteen accurate 3D skull models were produced and five metrics were determined. The 3D linear measurements were compared to measurements taken manually with a digital caliper. In addition, repetitive measurements were recorded by varying researchers to determine repeatability. To allow for comparison straight line measurements were taken with the software, assuming that close accord with all manually measured features would illustrate the model's accurate replication of reality. Measurements were not significantly different demonstrating that realistic 3D skull models can be successfully produced to provide a consistent basis for craniometrics, with the additional benefit of allowing non-linear measurements if required.

Impact of Resolution and Texture of Laser Scanning Generated Three‐Dimensional Models on Landmark Identification

“…Advanced imaging technologies produce twodimensional (2D) and three-dimensional (3D) images, which allow various metric analyses in virtual environment. There are numerous studies comparing the reliability and accuracy of measurements obtained by direct craniometric approaches with those measured on 3D models generated by different technologies such as laser scanning (Park et al, 2006;Richard et al, 2014;Toneva et al, 2016;Toneva et al, 2017b;Thoma et al, 2018), multi-slice computed tomography (CT, Richard et al, 2014;Stull et al, 2014;Lorkiewicz-Muszy nska et al, 2015), cone-beam CT (Berco et al, 2009;Hassan et al, 2009;Damstra et al, 2010;Kamburo glu et al, 2011), industrial CT (Toneva et al, 2017a), 3D photogrammetry (Moshobane et al, 2016), as well as on 3D printed copies (Nizam et al, 2006;Richard et al, 2014). The accuracy of digital measurements depends to a large extent on the precision in landmark placement.…”