Single photon emission computed tomography (SPECT) is used in a variety of medical procedures, including myocardial perfusion, bone metabolism, and thyroid function studies. In SPECT, the emissions of a radionuclide within a patient are counted at a gamma camera to form a 2-dimensional projection of the 3-dimensional radionuclide distribution within the patient. This unknown 3-dimensional source distribution can be reconstructed from many 2-dimensional projections obtained at different angles around the patient. This reconstruction can be improved by properly modeling the physics in the patient, i.e., particle absorption and scattering. Currently, such modeling is done using statistical Monte Carlo methods, but deterministic codes have the potential to offer fast computation speeds while fully modeling particle interactions within the patient. Deterministic codes are not susceptible to statistical uncertainty, but have been over-looked for applications to nuclear medicine, most likely due to their own limitations, including discretization and large memory requirements. A novel deterministic reconstruction methodology for SPECT (DRS) has been developed to apply the advantages of deterministic algorithms to SPECT iterative image reconstruction. Using a maximum likelihood expectation maximization (ML-EM) algorithm, a deterministic code can fully model particle transport in the patient in the forward projection step, without the need of a large system matrix. The TITAN deterministic transport code has a SPECT formulation that allows for fast simulation of SPECT projection images and has been benchmarked through comparison with results from the SIMIND and MCNP5 Monte Carlo codes in this dissertation. The TITAN SPECT formulation has been improved through a modified collimator representation and full parallelization. The DRS methodology has been implemented in the TITAN code to create TITAN with Image Reconstruction (TITAN-IR). The TITAN-IR code has been used to successfully reconstruct the source distribution from SPECT data for the Jaszczak and NCAT phantoms. Extensive studies have been conducted to examine the sensitivity of TITAN-IR image quality to deterministic parameter selection as well as collimator blur and noise in the projection data being reconstructed. The TITAN-IR reconstruction has also been compared with other reconstruction algorithms. This novel image reconstruction methodology has been shown to reconstruct images in short computation times, demonstrating its potential in a clinical setting with further development. / Ph. D.

This work reports three reconstruction algorithms developed to address the practical issues encountered in 3D tomography diagnostics, such as the limited view angles available in many practical applications, the large scale and nonlinearity of the problems when they are in 3D, and the measurement uncertainty. These algorithms are: an algebraic reconstruction technique (ART) screening algorithm, a nonlinear iterative reconstruction technique (NIRT), and an iterative reconstruction technique integrating view registration optimization (IRT-VRO) algorithm. The ART screening algorithm was developed to enhance the performance of the traditional ART algorithm to solve linear tomography problems, the NIRT was to solve nonlinear tomography problems, and the IRT-VRO was to address the issue of view registration uncertainty in both linear and nonlinear problems. This dissertation describes the mathematical formulations, and the experimental and numerical validations for these algorithms. It is expected that the results obtained in this dissertation to lay the groundwork for their further development and expanded adaption in the deployment of tomography diagnostics in various practical applications. / Ph. D.

The purpose of this study was to explore what strategy the U.S. Department of Defense should use and how its forces may/should be arrayed in future peace building and post-conflict reconstruction operations. The nature of the research for this study was analytical and qualitative. It considers U.S. Army as well as joint doctrine, and explores the recent scholarly literature on military efforts at peace building and post-conflict reconstruction. Based on this study, the author recommends the following as necessary implementations to U.S. doctrine and policy: 1) Revise NSPD-44, 2) Require a direct habitual relationship for training, planning, and operations between CRC and DOD, 3) Expand applicable training for CA personnel as well as other military officers, and 4) Revamp deployment cycle for civil-military peacebuilding and post-conflict reconstruction operations. / Master of Arts

No / Stonehenge is one of the world’s most iconic archaeological sites and yet we know relatively little about the people that created this important prehistoric monument. This chapter contributes to this narrative by reconstructing the face of a high-status male who was recovered during nineteenth-century excavation of a Neolithic Long Barrow. Situated in the barrow cemetery at Winterbourne Stoke, this site is important to the contextual setting and contemporary development of Stonehenge as a ceremonial and ritual centre. The chapter reports on the combination of digital bioarchaeology and visual heritage methods, together with forensic reconstruction, that transformed the physical remains of the individual into digital data that was manipulated for 3D printing; and subsequent anatomical and visual art interpretation to yield physical life-like characteristics. His facial features have been rebuilt on the 3D printed skull, muscle by muscle, to create a highly realistic face from the era. The aim of this project was to provide a tangible connection to the archaeology of the Stonehenge landscape and to the people that developed its ceremonial and ritual significance—narrowing the temporal distance through the emotional experience it means to gaze into the eyes of a Neolithic individual.

In general, stereovision can be defined as a two part problem. The first is the correspondence problem. This involves determining the image point in each image of a set of images that correspond to the same physical point P. We will call this set of image points, N. The second problem is the reconstruction problem. Once a set of image points, N, that correspond to point P has been determined, N is then used to extract three dimensional information about point P. This master's thesis presents three novel solutions to the reconstruction problem. Two of the techniques presented are for detecting the location of a 3-D point and one for detecting a line expressed in a three dimensional coordinate system. These techniques are tested and validated using a unique 3-D finger detection algorithm. The techniques presented are unique because of their simplicity and because they do not require the cameras to be placed in specific locations, orientations or have specific alignments. On the contrary, it will be shown that the techniques presented in this thesis allow the two cameras used to assume almost any relative pose provided that the object of interest is within their field of view. The relative pose of the cameras at a given instant in time, along with basic equations from the perspective image model are used to form a system of equations that when solved, reveal the 3-D coordinates of a particular fixed point of interest or the three dimensional equation of a fixed line of interest. Finally, it will be shown that a single moving camera can successfully perform the same line and point detection accomplished by two cameras by altering the pose of the camera. The results presented in this work are beneficial to any typical stereovision application because of the computational ease in comparison to other point and line reconstruction techniques. But more importantly, this work allows for a single moving camera to perceive three-dimensional position information, which effectively removes the two camera constraint for a stereo vision system. When used with other monocular cues such as texture or color, the work presented in this thesis could be as accurate as binocular stereo vision at interpreting three dimensional information. Thus, this work could potentially increase the three dimensional perception of a robot that normally uses one camera, such as an eye-in-hand robot or a snake like robot.

The issue of reconstruction has appealed to many nations that have moved from significant transitional periods, be it economic, social, and or political. This has made the reconstruction theology, a relevant theology. This study is a result of realities unfolding in Zimbabwe which left many to ask what is missing in Zimbabwe in order to have a better society. The study seeks to contribute to the reconstruction theology debate from a missiological perspective which is based on asking and answering the question, “what is the role of the Christian Church in reconstruction?” At the onset, the study seeks to assert the applicability of the Ezra - Nehemiah Motif in Zimbabwe. The research is motivated by the premise that the church ought to have the capacity to adequately formulate a public-social theology which meets the demands of society. It is on this basis that the research will grapple with the concerns for justice, aspects of difference in relationship to human life- human dignity, policies of democratisation and democracy, social development and societal peaceful coexistence. The theology of reconstruction has been argued as a praxis and deed-oriented model of rebuilding. Whilst appreciating the Liberation Theology and its value to Zimbabwe, it could be argued further that the liberation has served the purpose and the need for a complementary theology; - Reconstruction Theology. However, if this assertion is to be upheld, questions may be raised as to whether Reconstruction Theology seeks to replace Liberation Theology. It is therefore through this research that it can be established whether there is a replacement of or a complement of liberation theology with reconstruction theology. This research then aims to analyse the deplorable Zimbabwean, socio-economic and socio-political fibers that require reconstruction and transformation, to enable development of a better society in which human dignity is respected. Further to that, the research explores and reflects upon the theological and missiological models of reconstruction that could be considered in post-colonial Zimbabwe. It is in this research that some alternative cultural variables, which could help achieve national reconstruction are deconstructed in light of reconstruction of Zimbabwe. To achieve this research utilises African Renaissance as its theoretical framework and informed by social construction theory. This research engages in the quantitative and qualitative research methods, supported by interviews and questionnaires. There is a plethora of produced in published and unpublished literature that enriched this thesis. Furthermore, the research utilised various methodological approaches which includes theological, sociological, and post-colonial. The research will then comprise nine chapters subtitled depending on the matters of concern. / Thesis (PhD)--University of Pretoria, 2018. / Science of Religion and Missiology / PhD / Unrestricted

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Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

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The art of reconstructing a real-world scene digitally has been on the mind of researchers for decades. Recently, it has attracted more and more attention from companies seeing a chance to bring this kind of technology to the market. Digital reconstruction of buildings in particular is a niche that has both potential and room for improvement. With this background, this thesis will present the design and evaluation of a pipeline made to find and correct approximately flat surfaces in architectural scenes. The scenes are 3D-reconstructed triangle meshes based on RGB images. The thesis will also comprise an evaluation of a few different components available for doing this, leading to a choice of best components. The goal is to improve the visual quality of the reconstruction. The final pipeline is designed with two blocks - one to detect initial plane seeds and one to refine the detected planes. The first block makes use of a multi-label energy formulation on the graph that describes the reconstructed surface. Penalties are assigned to each vertex and each edge of the graph based on the vertex labels, effectively describing a Markov Random Field. The energy is minimized with the help of the alpha-expansion algorithm. The second block uses heuristics for growing the detected plane seeds, merging similar planes together and extracting deviating details. Results on several scenes are presented, showing that the visual quality has been improved while maintaining accuracy compared with ground truth data. / Konsten att digitalt rekonstruera en verklig miljö har länge varit intressant för forskare. Nyligen har området även tilldragit sig mer och mer uppmärksamhet från företag som ser en möjlighet att föra den här typen av teknik till produkter på marknaden. I synnerhet är digital rekonstruktion av byggnader en nisch som har både stor potential och möjlighet till förbättring. Med denna bakgrund så presenterar detta examensarbete designen för och utvärderingen av en pipeline som skapats för att detektera och rätta till approximativt platta regioner i arkitektoniska miljöer. Miljöerna är 3D-rekonstruerade triangelmeshar skapade från RGB-bilder. Examensarbetet omfattar även utvärdering av olika komponenter för att uppnå detta, som avslutas med att de mest lämpliga komponenterna presenteras. Målet i korthet är att förbättra den visuella kvaliteten av en rekonstruerad modell. Den slutgiltiga pipelinen består av två övergripande block - ett för att detektera initiala plan och ett för att förbättra de funna planen. Det första blocket använder en multi-label energiformulering på grafen som beskriver den rekonstruerade ytan. Straffvärden tilldelas varje vertex och varje båge i grafen baserade på varje vertex label. På så sätt beskriver grafen ett Markov Random Field. Energin är sedan minimerad med alpha-expansion-algoritmen. Det andra blocket använder heuristiker för att låta planen växa, slå ihop närliggande plan och för att extrahera avvikande detaljer. Resultat på flera miljöer presenteras också för att påvisa att den visuella kvaliteten har förbättrats utan att rekonstruktionens noggrannhet har försämrats jämfört med ground truth-data.