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

A Survey of Geometric Analysis in Cultural Heritage

We present a review of recent techniques for performing geometric analysis in cultural heritage (CH) applications. The survey is aimed at researchers in the areas of computer graphics, computer vision and CH computing, as well as to scholars and practitioners in the CH field. The problems considered include shape perception enhancement, restoration and preservation support, monitoring over time, object interpretation and collection analysis. All of these problems typically rely on an understanding of the structure of the shapes in question at both a local and global level. In this survey, we discuss the different problem forms and review the main solution methods, aided by classification criteria based on the geometric scale at which the analysis is performed and the cardinality of the relationships among object parts exploited during the analysis. We finalize the report by discussing open problems and future perspectives

Human Skull Repairing Technologies Based on Heat Kernels

在人类学与法医学中，专家们常常利用发掘得到的头骨来还原死者生前的 面貌。由于自然环境的侵蚀与人为的破坏，挖掘出额骨骼往往呈碎片状，并且 在面部等包含丰富几何信息的区域出现破洞、裂隙等数据丢失的问题，直接对 这些碎片进行分析处理是十分困难的。随着三维扫描技术的发展，三维扫描仪 能够将实际的头骨扫描成电子数据存储在计算机内，并利用几何处理技术来对 头骨模型进行还原和修复，还原得到的头骨模型为后续的分析处理工作带来极 大的便利。因此，做为脸部重建的预处理程序，头骨模型的的还原与修复是计 算机图形学的重要研究课题，本文针对计算机环境下的头骨碎片拼接与破洞修 补提出了解决方法。 本文介...With the development of science and technology, facial reconstruction based on human skull is integrated by many disciplines, and has been continuously evolving and developing. To protect the original skull from any damaging, skulls are usually transformed into digital data by 3D scanner and stored in computers as triangle mesh. Skulls are sometimes fragmented; facial regions with rich geometr...学位：工程硕士院系专业：信息科学与技术学院_控制工程学号：2322010115321

Evaluation of a custom made anatomical guide for orthognathic surgery

Orthognathic surgery is a routinely used surgical technique for the correction of dento-facial deformities. During a Le Fort I orthognathic procedure the maxilla is surgically separated from the skull and the surgical positioning wafer is placed between the occlusal surfaces of the upper and lower dentition. However, the physiological response to general aesthesia results in loss of muscle tone in the mandible, which has a profound influence on the correct amount of maxillary advancement required. The expertise and visual judgement of the surgeon is relied upon to foresee and eliminate this potential source of error. However, this may not be possible to achieve in all cases, therefore there is a need for a device to guide the surgical position of the maxilla independent of the mandibular dentition. The aim of this study was to design and validate a custom made anatomical repositioning surgical framework for accurately repositioning the maxilla independently of the mandible during a Le Fort I osteotomy. A single plastic anatomical skull was scanned using a helical Computed Tomography (CT) scanner. Utilising 3D manipulation software, forty-three Le Fort I orthognathic surgery movements were planned. A custom made anatomical repositioning guide was designed and 3D printed for all movements. Each guide was used to reposition the maxilla of the physical skull and then laser scanned using a GOM blue light scanner. GOMinspect software was used to compare the planned and physical position of the repositioned maxilla. The results of the experiment were statistically evaluated.Orthognathic surgery is a routinely used surgical technique for the correction of dento-facial deformities. During a Le Fort I orthognathic procedure the maxilla is surgically separated from the skull and the surgical positioning wafer is placed between the occlusal surfaces of the upper and lower dentition. However, the physiological response to general aesthesia results in loss of muscle tone in the mandible, which has a profound influence on the correct amount of maxillary advancement required. The expertise and visual judgement of the surgeon is relied upon to foresee and eliminate this potential source of error. However, this may not be possible to achieve in all cases, therefore there is a need for a device to guide the surgical position of the maxilla independent of the mandibular dentition. The aim of this study was to design and validate a custom made anatomical repositioning surgical framework for accurately repositioning the maxilla independently of the mandible during a Le Fort I osteotomy. A single plastic anatomical skull was scanned using a helical Computed Tomography (CT) scanner. Utilising 3D manipulation software, forty-three Le Fort I orthognathic surgery movements were planned. A custom made anatomical repositioning guide was designed and 3D printed for all movements. Each guide was used to reposition the maxilla of the physical skull and then laser scanned using a GOM blue light scanner. GOMinspect software was used to compare the planned and physical position of the repositioned maxilla. The results of the experiment were statistically evaluated

The Development And Application Of A Statistical Shape Model Of The Human Craniofacial Skeleton

Biomechanical investigations involving the characterization of biomaterials or improvement of implant design often employ finite element (FE) analysis. However, the contemporary method of developing a FE mesh from computed tomography scans involves much manual intervention and can be a tedious process. Researchers will often focus their efforts on creating a single highly validated FE model at the expense of incorporating variability of anatomical geometry and material properties, thus limiting the applicability of their findings. The goal of this thesis was to address this issue through the use of a statistical shape model (SSM). A SSM is a probabilistic description of the variation in the shape of a given class of object. (Additional scalar data, such as an elastic constant, can also be incorporated into the model.) By discretizing a sample (i.e. training set) of unique objects of the same class using a set of corresponding nodes, the main modes of shape variation within that shape class are discovered via principal component analysis. By combining the principal components using different linear combinations, new shape instances are created, each with its own unique geometry while retaining the characteristics of its shape class. In this thesis, FE models of the human craniofacial skeleton (CFS) were first validated to establish their viability. A mesh morphing procedure was then developed to map one mesh onto the geometry of 22 other CFS models forming a training set for a SSM of the CFS. After verifying that FE results derived from morphed meshes were no different from those obtained using meshes created with contemporary methods, a SSM of the human CFS was created, and 1000 CFS FE meshes produced. It was found that these meshes accurately described the geometric variation in human population, and were used in a Monte Carlo analysis of facial fracture, finding past studies attempting to characterize the fracture probability of the zygomatic bone are overly conservative

Reconstrução de crânios fragmentados e avaliação de ancestralidade

Mestrado em Engenharia de Computadores e TelemáticaIn archaeological sites, it is common to find fragmented human osteological remains, namely skulls. The main goal of this dissertation is to investigate processes to create reconstructions using three dimensional models(3D) in order to allow the study of fragmented skulls. This work also aims to improve the application CraMs, Craniometric Measurements, by adding new functionality to reassemble skull fragments and expanding the ancestry classification using statistical analysis. This application was initially developed in the context of a Master dissertation with the goal of assisting the anthropologist’s work in performing craniometric measurements and by using 3D models of the individuals reduce the variability in the measurements obtained by the different specialists while at the same time contributing to the preservation of the specimens. The work developed in this dissertation is focused on the reconstruction of specimens that are in a fragmented state to be later analyzed with CraMs, something which was not previously possible. Methods were also developed to allow for a centralized storage of previous analysis by anthropologists and use them to estimate the ancestry of an individual using statistical analysis.Em escavações arqueológicas é comum recuperarem-se restos osteológicos humanos fragmentados, nomeadamente os crânios. É o principal objetivo desta dissertação estudar métodos para criar uma reconstrução usando modelos tridimensionais (3D) que permita o estudo antropológico de crânios fragmentados. Este trabalho pretende também melhorar a aplicação CraMs, Craniometric Measurements, integrando funcionalidades para reconstrução de crânios fragmentados e novos métodos de classificação da ancestralidade baseados em análise estatística. Esta aplicação foi inicialmente desenvolvida com o objetivo de auxiliar o trabalho dos antropólogos na realização de medidas craniométricas e, com base em modelos 3D dos espécimes, permite reduzir a variabilidade nas medidas obtidas pelos diferentes especialistas ajudando simultaneamente na preservação dos espécimes. O trabalho desenvolvido nesta dissertação está focado na reconstrução de espécimes que estão num estado fragmentado para serem posteriormente analisados na aplicação CraMs, o que era previamente não era possível. Foram também desenvolvidos métodos que permitem o armazenamento centralizado de análises feitas pelos antropólogos e a sua utilização para estimar a ancestralidade de um indivíduo usando análise estatística

Reassembly of fractured object using fragment topology

This work presents our results on reassembly of broken objects using a newly developed fragment topology and feature extraction methodology. The reassembly of broken objects is a common problem in different domains including computeraided bone fracture reduction and reassembly of broken artefacts . The new fragment topology combines information from intact and fractured region boundaries to reduce possible correspondences between the fragments and optimise our iterative matching process. Experiments performed on different multifragment objects show that the proposed topology can be effectively applied, completing the process in a small number of iterations and with average alignment error 0.12mm

A High Density Micro-Electrocorticography Device for a Rodent Model

Electrocorticography (ECoG) is a methodology for stable mapping of the brain surface using local field potentials (LFPs) with a wide cortical region, high signal fidelity, and minimal invasiveness to brain tissue. To compare surface ECoG signals with inter-cortical neuronal activity, we fabricated a flexible handcrafted ECoG electrode made with economically available materials. This research is on a Lewis rat implanted with a handcrafted 256-channel, non-penetrative ECoG electrode covering an area of 7mm x 7mm on the cortical surface. This device was placed on the motor and somatosensory cortex of the brain to record signals with an active animal. The recordings are acquired by using the Synapse Software and the Tucker-Davis Technologies acquisition system to monitor and analyze electrophysiological signals within the amplitude range of 200µV for local field potentials. This demonstrates how reactive channels and their spatiotemporal and frequency-specific characteristics can be identified by means of this method