Effective 3D Geometric Matching for Data Restoration and Its Forensic Application

3D geometric matching is the technique to detect the similar patterns among multiple objects. It is an important and fundamental problem and can facilitate many tasks in computer graphics and vision, including shape comparison and retrieval, data fusion, scene understanding and object recognition, and data restoration. For example, 3D scans of an object from different angles are matched and stitched together to form the complete geometry. In medical image analysis, the motion of deforming organs is modeled and predicted by matching a series of CT images. This problem is challenging and remains unsolved, especially when the similar patterns are 1) small and lack geometric saliency; 2) incomplete due to the occlusion of the scanning and damage of the data. We study the reliable matching algorithm that can tackle the above difficulties and its application in data restoration. Data restoration is the problem to restore the fragmented or damaged model to its original complete state. It is a new area and has direct applications in many scientific fields such as Forensics and Archeology. In this dissertation, we study novel effective geometric matching algorithms, including curve matching, surface matching, pairwise matching, multi-piece matching and template matching. We demonstrate its applications in an integrated digital pipeline of skull reassembly, skull completion, and facial reconstruction, which is developed to facilitate the state-of-the-art forensic skull/facial reconstruction processing pipeline in law enforcement

New Insights into the Skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea)

The skull of the Cretaceous pterosaur Istiodactylus latidens, a historically important species best known for its broad muzzle of interlocking, lancet-shaped teeth, is almost completely known from the broken remains of several individuals, but the length of its jaws remains elusive. Estimates of I. latidens jaw length have been exclusively based on the incomplete skull of NHMUK R3877 and, perhaps erroneously, reconstructed by assuming continuation of its broken skull pieces as preserved in situ. Here, an overlooked jaw fragment of NHMUK R3877 is redescribed and used to revise the skull reconstruction of I. latidens. The new reconstruction suggests a much shorter skull than previously supposed, along with a relatively tall orbital region and proportionally slender maxilla, a feature documented in the early 20th century but ignored by all skull reconstructions of this species. These features indicate that the skull of I. latidens is particularly distinctive amongst istiodactylids and suggests greater disparity between I. latidens and I. sinensis than previously appreciated. A cladistic analysis of istiodactylid pterosaurs incorporating new predicted I. latidens skull metrics suggests Istiodactylidae is constrained to five species (Liaoxipterus brachyognathus, Lonchengpterus zhoai, Nurhachius ignaciobritoi, Istiodactylus latidens and Istiodactylus sinensis) defined by their distinctive dentition, but excludes the putative istiodactylids Haopterus gracilis and Hongshanopterus lacustris. Istiodactylus latidens, I. sinensis and Li. brachyognathus form an unresolved clade of derived istiodactylids, and the similarity of comparable remains of I. sinensis and Li. brachyognathus suggest further work into their taxonomy and classification is required. The new skull model of I. latidens agrees with the scavenging habits proposed for these pterosaurs, with much of their cranial anatomy converging on that of habitually scavenging birds

The reproducibility of incomplete skulls using freeform modeling plus software

As early as 1883, forensic artists and forensic anthropologists have utilized forensic facial reconstruction in the attempt to identify skulls from decomposed remains. Common knowledge dictates that in order to complete identification from the skull with facial reconstruction, the splanchnocranium (also known as the viscerocranium or facial portion of the skull) needs to still be intact. However, there has been very little research conducted (Colledge 1996; Ismail 2008; Wilkinson and Neave 2001) to determine the minimal amount of intact skull that can be present for a reconstruction to still be possible and accurate. Accordingly, in the present study, the researcher attempted to prove that a skull with significant damage to the splanchnocranium could be repaired and facially reconstructed to bear a likeness to the original skull and face. Utilizing FreeForm Modeling Plus Software, version 11.0 (Geomagic Solutions - Andover, MA), in conjunction with the Phantom Desktop Haptic Device (Geomagic Solutions - Andover, MA), five CT scans of males between 19 and 40 years old and of varying ethnicities (four Caucasian and one Asian) were digitally altered to present significant skull damage to the splanchnocranium. The hard tissue digital images were repaired using the same software mentioned above and template skulls (i.e., superfluous CT scanned skulls of similar age, sex, and ancestry). The soft tissue digital images were facially reconstructed also utilizing the same software mentioned above and by following basic tissue depth charts/placement rules and guidelines for feature reconstruction. The reconstructed images were compared to their original CT scans in a side-by-side comparison. Assessors were given a rating scale rubric to fill out that asked them specific questions pertaining to both certain facial features and overall similarity between the original and reconstructed images. Two of the reconstructions each ranked an overall 29% "close resemblance" to their original counterparts, one was ranked an overall 71% "no resemblance" to its original counterpart, and the other three fell somewhere in the middle ("slight" or "approximate") in the rating scale. The results reflected a number of issues related to this project (i.e., the researcher's lack of artistic skill) and to facial reconstruction in general (i.e., tissue depth measurement charts) and showed that while it is not impossible to reconstruct skulls that had been damaged in some capacity, the accuracy of the resulting facial reconstruction is questionable. Future studies would benefit from using an artist to reconstruct the images rather than someone with little to no experience in the field, a larger sample size consisting of one ancestry to avoid the cross-race effect, a comparison of the original skull to the repaired one utilizing Geomagic Qualify (Geomagic Solutions - Andover, MA) to glean an overall view of the project's accuracy, and utilization of a photo lineup as the method of comparison in addition to a side-by-side comparison to give a more realistic feel to the comparison process

Virtual 3D Reconstruction of Archaeological Pottery Using Coarse Registration

The 3D reconstruction of objects has not only improved visualisation of digitised objects, it has helped researchers to actively carry out archaeological pottery. Reconstructing pottery is significant in archaeology but is challenging task among practitioners. For one, excavated potteries are hardly complete to provide exhaustive and useful information, hence archaeologists attempt to reconstruct them with available tools and methods. It is also challenging to apply existing reconstruction approaches in archaeological documentation. This limitation makes it difficult to carry out studies within a reasonable time. Hence, interest has shifted to developing new ways of reconstructing archaeological artefacts with new techniques and algorithms. Therefore, this study focuses on providing interventions that will ease the challenges encountered in reconstructing archaeological pottery. It applies a data acquisition approach that uses a 3D laser scanner to acquire point cloud data that clearly show the geometric and radiometric properties of the object’s surface. The acquired data is processed to remove noise and outliers before undergoing a coarse-to-fine registration strategy which involves detecting and extracting keypoints from the point clouds and estimating descriptions with them. Additionally, correspondences are estimated between point pairs, leading to a pairwise and global registration of the acquired point clouds. The peculiarity of the approach of this thesis is in its flexibility due to the peculiar nature of the data acquired. This improves the efficiency, robustness and accuracy of the approach. The approach and findings show that the use of real 3D dataset can attain good results when used with right tools. High resolution lenses and accurate calibration help to give accurate results. While the registration accuracy attained in the study lies between 0.08 and 0.14 mean squared error for the data used, further studies will validate this result. The results obtained are nonetheless useful for further studies in 3D pottery reassembly

Development of a statistical shape and appearance model of the skull from a South African population

Statistical shape models (SSMs) and statistical appearance models (SAMs) have been applied in medical analysis such as in surgical planning, finite element analysis, model-based segmentation, and in the fields of anthropometry and forensics. Similar applications can make use of SSMs and SAMs of the skull. A combination of the SSM and SAM of the skull can also be used in model-based segmentation. This document presents the development of a SSM and a SAM of the human skull from a South African population, using the Scalismo software package. The SSM development pipeline was composed of three steps: 1) Image data segmentation and processing; 2) Development of a free-form deformation (FFD) model for establishing correspondence across the training dataset; and 3) Development and validation of a SSM from the corresponding dataset. The SSM was validated using the leave one-out cross-validation method. The first eight principal components of the SSM represented 92.13% of the variation in the model. The generality of the model in terms of the Hausdorff distance between a new shape generated by the SSM and instances of the SSM had a steady state value of 1.48mm. The specificity of the model (in terms of Hausdorff distance) had a steady state value of 2.04mm. The SAM development pipeline involved four steps: 1) Volumetric mesh generation of the reference mesh to be used in establishing volumetric correspondence; 2) Sampling of intensity values from original computed tomography (CT) images using the in-correspondence volumetric meshes; and 3) Development of a SAM from the in-correspondence intensity values. A complete validation of the SAM was not possible due to limitations of the Scalismo software. As a result, only the shapes of the incomplete skulls were reconstructed and thereby validated. The amount of missing detail, as represented by absent landmarks, affected the registration results. Complete validation of the SAM is recommended as future work, via the use of a combined shape and intensity model (SSIM)

A study of dental disease in the horse

Summary avaiilable; p. iii-iv

The Image Bank: Reflections on an Incomplete Archive

This thesis examines the development of a digital archive for The Image Bank at GSU as a process of excavation and reconstruction. It defines the digital archive as a medium for the institutionalization of knowledge, its reproduction, and preservation. In addition, this thesis examines the digital archive as it operates on a continuum of materiality and immateriality, encompassing fractured distinctions between its possibilities and impossibilities in an increasingly dematerialized digitized landscape

Prevalence and patterns of disease in early medieval populations : a comparison of skeletal samples from fifth to eighth century AD Britain and Southwestern Germany

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