Abstract:

In anthropology, craniometry is an important means for obtaining human skull dimensional information and other characteristics. Computed tomography (CT) and three-dimensional (3D) reconstruction technologies offer significant advantages to craniometry specialists by facilitating both the collection of repeated measurements and analysis of inner structures without destroying specimens. However, the influence of 3D reconstruction precision based on dry skull measurements is unclear. MIMICS, one of several commonly used 3D reconstruction software packages, provides users with the choice to select from four quality settings during the 3D model reconstruction process: low, medium, high and optimal. Ultimately, lower quality corresponds with a smaller file size and faster modeling computing speeds. In this study, four models were generated from a single skull using each of the four quality settings. Measurements were made of the parietal sagittal chord, cranial horizontal circumference, cranial surface area, cranial capacity, mastoid cell system surface area, and mastoid cell system volume of 43 reconstructed Yunnan modern human cranial specimens modeled using MIMICS. According to matrix simplification rules of MIMICS, optimal quality models were chosen as the standard for paired t-tests or non-parametric tests followed by the calculation of measurement difference (expressed as a percentage). Results indicated that the high-quality modeling group, including the parietal sagittal chord and mastoid cell system surface area measurements exhibited no difference in optimal quality. Conversely, measurement data of the other four characteristics used to generate simplified quality models significantly differed from optimal quality model data. Notably, measurement differences between simplified and optimal quality models of sagittal chord, cranial horizontal circumference, surface area of cranium, and cranial capacity were below 3%, while absolute values of measurement differences between low and optimal quality measurements of mastoid cell system surface area and volume exceeded 50% and 120%, respectively. These results suggest that low-quality 3D reconstruction models can be useful for measurements of large-scale morphological features with smooth surfaces. As for small-scale morphological features with rough surfaces such as the internal cavity sinus of the skull, three-dimensional reconstruction quality parameters must be selected very carefully.

Key words: MIMICS, CT, 3D reconstruction, Measurements, Biological anthropology