Technical note: Reliability of Suchey-Brooks and Buckberry-Chamberlain methods on 3D visualizations from CT and laser scans. (original) (raw)
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Waltenberger, L., Rebay-Salisbury, K., and Mitteroecker, P. 2021. Three-dimensional surface scanning methods in osteology: A topographical and geometric morphometric comparison. American Journal of Physical Anthropology 174: 846-858.
Abstract Objectives Three‐dimensional (3D) data collected by structured light scanners, photogrammetry, and computed tomography (CT) scans are increasingly combined in joint analyses, even though the scanning techniques and reconstruction software differ considerably. The aim of the present study was to compare the quality and accuracy of surface models and landmark data obtained from modern clinical CT scanning, 3D structured light scanner, photogrammetry, and MicroScribe digitizer. Material and methods We tested 13 different photogrammetric software tools and compared surface models obtained by different methods for four articulated human pelves in a topographical analysis. We also measured a set of 219 landmarks and semilandmarks twice on every surface as well as directly on the dry bones with a MicroScribe digitizer. Results Only one photogrammetric software package yielded surface models of the complete pelves that could be used for further analysis. Despite the complex pelvic anatomy, all three methods (CT scanning, 3D structured light scanning, photogrammetry) yielded similar surface representations with average deviations among the surface models between 100 and 200 μm. A geometric morphometric analysis of the measured landmarks showed that the different scanning methods yielded similar shape variables, but data acquisition via MicroScribe digitizer was most prone to error. Discussion We demonstrated that three‐dimensional models obtained by different methods can be combined in a single analysis. Photogrammetry proved to be a cheap, quick, and accurate method to generate 3D surface models at useful resolutions, but photogrammetry software packages differ enormously in quality.
Advances in Archaeological Practice, 2021
The production of three-dimensional (3D) digital meshes of surface and computed tomographic (CT) data has become widespread in morphometric analyses of anthropological and archaeological data. Given that processing methods are not standardized, this leaves questions regarding the comparability of processed and digitally curated 3D datasets. The goal of this study was to identify those processing parameters that result in the most consistent fit between CT-derived meshes and a 3D surface model of the same human mandible. Eight meshes, each using unique thresholding and smoothing parameters, were compared to assess whole-object deviations, deviations along curves, and deviations between specific anatomical features on the surface model when compared with the CT scans using a suite of comparison points. Based on calculated gap distances, the mesh that thresholded at "0" with an applied smoothing technique was found to deviate least from the surface model, although it is not the most biologically accurate. Results have implications for aggregated studies that employ multimodal 3D datasets, and caution is recommended for studies that enlist 3D data from websites and digital repositories, particularly if processing parameters are unknown or derived for studies with different research foci.
This paper introduces a new methodological approach to the quantification of cross-sectional geometric properties based on 3D laser scan data. A variety of methods have been used to calculate estimates of rigidity in the diaphyses of long bones. CT scan, biplanar radiograph, and periosteal mould techniques have all been applied to collect image data of bone sections to assess biomechanical properties (cross-sectional area and second moments of area). Whilst direct quantification of both endosteal and periosteal contours allows the greatest accuracy, such data correlate highly with a periosteal-only approach that is of greater practical application in many contexts. The advent of non-invasive 3D laser scan technologies presents a method to capture bone surface morphology that can be applied to the study of variation in the cross-sectional properties of human bones. This study tests the correspondence between cross-sectional geometric properties derived from laser scans to those obtained through traditional approaches (periosteal moulding and biplanar radiography). A custom-built program, AsciiSection, is introduced for the automated analysis of biomechanical properties direct from 3D coordinate data. The results indicate that the AsciiSection method is of comparable if not greater accuracy than traditional moulding techniques. The study suggests that there is a strong correlation between mid-diaphyseal cortical bone distribution and cross-sectional geometry calculated using laser scans. The approach provides a viable alternative to traditional techniques for the estimation of biomechanical properties and also allows the collection of rich data and descriptions of morphological variation along the diaphysis.
Collegium antropologicum
The aim of this study is to compare two different methods of frontal bone surface model acquisition. Three dimensional models acquired by laser scanning were compared with models of the same bones acquired by virtual replicas reconstructed from a sequence of computed tomography (CT) images. The influence of volumetric CT data processing (namely thresholding), which immediately preceded the generation of the three-dimensional surface model, was also considered and explored in detail in one sample. Despite identifying certain areas where both models showed deviations across all samples, their conformity can be generally classified as satisfactory, and the differences can be regarded as minimal. The average deviation of registered surface models was 0.27 mm for 90% of the data, and its value was therefore very close to the resolution of the laser scanner used.
International Journal of Osteoarchaeology, 2011
A total of 11 340 Cartesian coordinates of 42 homologous landmarks on five excavated human crania were recorded by three observers using a three-dimensional (3D) digitiser and computer models created with a 3D laser scanner. The aim was to compare the errors of the coordinate data of landmarks of different types recorded with these two techniques. The results showed that digitiser-based and 3D model-based coordinate measurements had overall standard deviations of, respectively, ±0.79 and ±1.05 mm. However, the 3D digitiser yielded the most precise coordinate data for landmarks defined primarily by biological criteria (Type I landmarks), while the 3D laser scanner models yielded the most precise coordinate data for landmarks defined primarily by geometric criteria (Type III landmarks). These findings are likely to influence the research design of future craniometric studies, as they indicate that the suitability of certain landmark types as reference points for geometric operations, such as partial Procrustes analysis, depends on the method by which they are measured. This information is particularly important for retrospective research or for combined databases such as FORDISC or CRANID, which may integrate different types of landmarks recorded by different researchers and/or instruments. Crania displaying poor preservation and surface discoloration yielded larger measurement errors, especially for the 3D model measurements. This is not surprising given that landmarks on 3D models cannot be located using tactile means, but have to be located solely on a visual basis. Nonetheless, even though the digitiser measurements exhibit an overall precision slightly greater than the 3D model measurements, both techniques yield coordinate data with a precision sufficient for most craniometric research.
The Identifiability of Osteological Traits on 3D Models of Human Skeletal Remains
Previous studies have entertained the prospect of having 3D models substitute for their dry bone originals in osteological analysis. The objective of this study was to contribute to qualifying to what extent this may be possible given current technology. To this purpose, rather than choosing just a quantitative and purely technical method for evaluating models, as has been the norm in previous studies, a qualitative method was also applied where the visual identifiability of the traits was taken as the standard. A cranium and a metatarsal bone were chosen as case studies, and three types of models were created of each specimen – a scan-based model, an image-based model and a model combining geometry from scans with textures from photos. The relative identifiability of the traits on the different models was graded and compared, and the factors that contributed to the results discussed. The study found that while 3D models may hold some advantages over photo documentation as substitutes to originals in osteological analysis, primarily due to preserving much of the originals’ geometry, the technology also suffers some disadvantages, notably that the textures’ image quality often fall short of photos, especially when superimposed on distorted geometry generated from scans. It can also prove difficult to create models capable of representing all parts of their originals equally well without making the models excessively heavy. Furthermore, the study showed that some morphological traits were more difficult to digitize and thus less identifiable on 3D models than others, and that qualitatively evaluating 3D models is a complex and challenging task. These results challenge assertions about the capabilities of 3D models in previous studies, and suggests that establishing a common standard for evaluating digital models, such as the identifiability of osteological traits introduced here, is a desirable development in digital osteology.