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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
221

Numerical modelling of full scale tidal turbines using the actuator disc approach

Abdul Rahman, Anas January 2018 (has links)
In recent years, the actuator disc approach which employs the Reynolds-Averaged Navier-Stokes (RANS) solvers has been extensively applied in wind and tidal energy field to estimate the wake of a horizontal axis turbine. This method is simpler to administer and requires moderate computational resources in modelling a tidal turbines rotor. Nonetheless, the use of actuator disc approximation in predicting the performance of tidal devices has been limited to studies involving an extremely small disc (e.g. rotor diameter of 0.1 meter). The drawback of a small scale actuator disc model is the overestimation of essential parameters such as the mesh density and the resolution of the vertical layers, making them impractical to be replicated in a regional scale model. Hence, this study aims to explore the methodology on implementation of the Three- Dimensional (3D) actuator disc-RANS model in an ocean scale simulation. Additionally, this study also aspires to examine the sensitivity of the applied momentum source term and its validity in representing full-size tidal devices. Nonetheless, before the effectiveness of an actuator disc in a regional model can be tested, tidal flow models for the area of interest needed to be set up first. This was essential for two reasons: (a) to ensure accurate hydrodynamic flow conditions at the deployment site were replicated, (b) to give confidence in the outputs produced by the regional scale actuator disc simulations, since in-situ turbine measurement data from a real deployment site were difficult to source. This research was undertaken in two stages; in the first stage, a numerical model which can simulate the tidal flow conditions of the deployment sites was constructed, and, in the second stage, the actuator disc method which is capable of modelling an array of real scale-sized tidal turbines rotors has been implemented. In the first stage, tidal flow simulations of the Pentland Firth and Orkney Waters (PFOW) were conducted using two distinct open-source software - Telemac3D, which is a finite element based numerical model, and Delft3D, which is a finite difference based model. Detailed methodologies in developing a 3D tidal flow model for the PFOW using both numerical models were presented, where their functionality, as well as limitations were explored. In the calibration and validation processes, both models demonstrated excellent comparison against the measured data. However, Telemac3D was selected for further modelling of the actuator disc considering the model's capability to perform parallel computing, together with its flexibility to combine both structured and unstructured mesh. In the second stage, to examine the actuator disc's accuracy in modelling a full size tidal device, the momentum source term was initially applied in an idealised channel study, where the presence of a 20-meter diameter turbine was simulated for both single and array configurations. The following parameters were investigated: (i) size of the unstructured mesh utilised in the computational domain, (ii) variation in disc's thickness, (iii) resolution of the imposed structured grid to represent turbine's enclosure, (iv) variation in the vertical layers, and (v) influence of hydrostatic and non-hydrostatic formulations on the models' outputs. It is to be noted that the turbine's support structures have not been included in the modelling. The predicted velocities and computed turbulence intensities from the models were compared against laboratory measurement data sourced from literature, where excellent agreement between the model outputs and the data from literature was observed. In essence, these studies highlighted the efficiency and robustness of the applied momentum source term in replicating the wake profiles and turbulence characteristics downstream of the disc, hence providing credence in implementing the actuator disc method for a regional scale application. Subsequently, the validated actuator disc method was applied to the Inner Sound region of the Pentland Firth to simulate arrays of up to 32 tidal turbine rotors. The wake development, flow interactions with the rotor arrays, and flow recovery at the Inner Sound region have been successfully mapped. Also, this study highlighted the importance of employing optimal numerical margins, specifically for the structured grid and horizontal planes, as both parameters were relevant in defining the disc's swept area. As published materials on the implementation of actuator disc approach within a regional scale model is still scarce, it was aspired that this work could provide some evidence, guidance and examples of suggested best practice in effort to fill the research gap in modelling tidal turbine arrays using the actuator disc approach.
222

Active haptic exploration for 3D shape reconstruction.

January 1996 (has links)
by Fung Wai Keung. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 146-151). / Acknowledgements --- p.viii / Abstract --- p.1 / Chapter 1 --- Overview --- p.3 / Chapter 1.1 --- Tactile Sensing in Human and Robot --- p.4 / Chapter 1.1.1 --- Human Hands and Robotic Hands --- p.4 / Chapter 1.1.2 --- Mechanoreceptors in skin and Tactile Sensor Arrays --- p.7 / Chapter 1.2 --- Motivation --- p.12 / Chapter 1.3 --- Objectives --- p.13 / Chapter 1.4 --- Related Work --- p.14 / Chapter 1.4.1 --- Using Vision Alone --- p.15 / Chapter 1.4.2 --- Integration of Vision and Touch --- p.15 / Chapter 1.4.3 --- Using Touch Sensing Alone --- p.17 / Chapter 1.4.3.1 --- Ronald S. Fearing's Work --- p.18 / Chapter 1.4.3.2 --- Peter K. Allen's Work --- p.22 / Chapter 1.5 --- Outline --- p.26 / Chapter 2 --- Geometric Models --- p.27 / Chapter 2.1 --- Introduction --- p.27 / Chapter 2.2 --- Superquadrics --- p.27 / Chapter 2.2.1 --- 2D Superquadrics --- p.27 / Chapter 2.2.2 --- 3D Superquadrics --- p.29 / Chapter 2.3 --- Model Recovery of Superquadric Models --- p.31 / Chapter 2.3.1 --- Problem Formulation --- p.31 / Chapter 2.3.2 --- Least Squares Optimization --- p.33 / Chapter 2.4 --- Free-Form Deformations --- p.34 / Chapter 2.4.1 --- Bernstein Basis --- p.36 / Chapter 2.4.2 --- B-Spline Basis --- p.38 / Chapter 2.5 --- Other Geometric Models --- p.41 / Chapter 2.5.1 --- Generalized Cylinders --- p.41 / Chapter 2.5.2 --- Hyperquadrics --- p.42 / Chapter 2.5.3 --- Polyhedral Models --- p.44 / Chapter 2.5.4 --- Function Representation --- p.45 / Chapter 3 --- Sensing Strategy --- p.54 / Chapter 3.1 --- Introduction --- p.54 / Chapter 3.2 --- Sensing Algorithm --- p.55 / Chapter 3.2.1 --- Assumption of objects --- p.55 / Chapter 3.2.2 --- Haptic Exploration Procedures --- p.56 / Chapter 3.3 --- Contour Tracing --- p.58 / Chapter 3.4 --- Tactile Sensor Data Preprocessing --- p.59 / Chapter 3.4.1 --- Data Transformation and Sensor Calibration --- p.60 / Chapter 3.4.2 --- Noise Filtering --- p.61 / Chapter 3.5 --- Curvature Determination --- p.64 / Chapter 3.6 --- Step Size Determination --- p.73 / Chapter 4 --- 3D Shape Reconstruction --- p.80 / Chapter 4.1 --- Introduction --- p.80 / Chapter 4.2 --- Correspondence Problem --- p.81 / Chapter 4.2.1 --- Affine Invariance Property of B-splines --- p.84 / Chapter 4.2.2 --- Point Inversion Problem --- p.87 / Chapter 4.3 --- Parameter Triple Interpolation --- p.91 / Chapter 4.4 --- 3D Object Shape Reconstruction --- p.94 / Chapter 4.4.1 --- Heuristic Approach --- p.94 / Chapter 4.4.2 --- Closed Contour Recovery --- p.97 / Chapter 4.4.3 --- Control Lattice Recovery --- p.102 / Chapter 5 --- Implementation --- p.105 / Chapter 5.1 --- Introduction --- p.105 / Chapter 5.2 --- Implementation Tool - MATLAB --- p.105 / Chapter 5.2.1 --- Optimization Toolbox --- p.107 / Chapter 5.2.2 --- Splines Toolbox --- p.108 / Chapter 5.3 --- Geometric Model Implementation --- p.109 / Chapter 5.3.1 --- FFD Examples --- p.111 / Chapter 5.4 --- Shape Reconstruction Implementation --- p.112 / Chapter 5.5 --- 3D Model Reconstruction Examples --- p.120 / Chapter 5.5.1 --- Example 1 --- p.120 / Chapter 5.5.2 --- Example 2 --- p.121 / Chapter 6 --- Conclusion --- p.128 / Chapter 6.1 --- Future Work --- p.129 / Appendix --- p.133 / Bibliography --- p.146
223

Mosaicking video with parallax.

January 2001 (has links)
Cheung Man-Tai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 81-84). / Abstracts in English and Chinese. / List of Figures --- p.vi / List of Tables --- p.viii / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- Background --- p.1 / Chapter 1.1.1. --- Parallax --- p.2 / Chapter 1.2. --- Literature Review --- p.3 / Chapter 1.3. --- Research Objective --- p.6 / Chapter 1.4. --- Organization of Thesis --- p.6 / Chapter Chapter 2. --- The 3-Image Algorithm --- p.1 / Chapter 2.1. --- Projective Reconstruction --- p.10 / Chapter 2.2. --- Epipolar Geometry and Fundamental Matrix --- p.11 / Chapter 2.3. --- Determine the Projective Mapping --- p.12 / Chapter 2.3.1. --- Conditions for Initial Matches --- p.13 / Chapter 2.3.2. --- Obtaining the Feature Correspondence --- p.17 / Chapter 2.4. --- Registering Pixel Element --- p.21 / Chapter 2.4.1. --- Single Homography Approach --- p.22 / Chapter 2.4.2. --- Multiple Homography Approach --- p.23 / Chapter 2.4.3. --- Triangular Patches Clustering --- p.24 / Chapter 2.4.3.1. --- Delaunay Triangulation --- p.25 / Chapter 2.5. --- Mosaic Construction --- p.29 / Chapter Chapter 3. --- The n-Image Algorithm --- p.31 / Chapter Chapter 4. --- The Uneven-Sampling-Rate n-Image Algorithm --- p.34 / Chapter 4.1. --- Varying the Reference-Target Images Separation --- p.35 / Chapter 4.2. --- Varying the Target-Intermediate Images Separation --- p.38 / Chapter Chapter 5. --- Experiments --- p.43 / Chapter 5.1. --- Experimental Setup --- p.43 / Chapter 5.1.1. --- Measuring the Performance --- p.43 / Chapter 5.2. --- Experiments on the 3-Image Algorithm --- p.44 / Chapter 5.2.1. --- Planar Scene --- p.44 / Chapter 5.2.2. --- Comparison between a Global Parametric Transformation and the 3-Image Algorithm --- p.46 / Chapter 5.2.3. --- Generic Scene --- p.49 / Chapter 5.2.4. --- The Triangular Patches Clustering against the Multiple Homography Approach --- p.52 / Chapter 5.3. --- Experiments on the n-Image Algorithm --- p.56 / Chapter 5.3.1. --- Initial Experiment on the n-Image Algorithm --- p.56 / Chapter 5.3.2. --- Another Experiment on the n-Image Algorithm --- p.58 / Chapter 5.3.3. --- the n-Image Algorithm over a Longer Image Stream --- p.61 / Chapter 5.4. --- Experiments on the Uneven-Sampling-Rate n-Image Algorithm --- p.65 / Chapter 5.4.1. --- Varying Reference-Target Images Separation --- p.65 / Chapter 5.4.2. --- Varying Target-Intermediate Images Separation --- p.69 / Chapter 5.4.3. --- Comparing the Uneven-Sampling-Rate n-Image Algorithm and Global Transformation Method --- p.73 / Chapter Chapter 6. --- Conclusion and Discussion --- p.76 / Bibliography --- p.81
224

A aplicação das imagens tridimensionais digitais como meio de comunicação visual entre arquiteto e cliente / The application of digital three-dimensional images as a visual communication between architect and customer / La aplicación de las imágenes tridimensionales digitales como medio de comunicación visual entre arquitecto y cliente

Fakhoury, Renata Svizzero 06 April 2018 (has links)
Submitted by Renata Svizzero Fakhoury (reefakhoury@gmail.com) on 2018-05-28T04:35:38Z No. of bitstreams: 1 DISSERTAÇÃO RENATA FAKHOURY.pdf: 6941532 bytes, checksum: c829c00c5d9f09a11f754a3bd8dd3310 (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-05-28T14:22:42Z (GMT) No. of bitstreams: 1 fakhoury_rs_me_bauru.pdf: 6525800 bytes, checksum: 924305300d1f4e62a2277a6beb1e313c (MD5) / Made available in DSpace on 2018-05-28T14:22:42Z (GMT). No. of bitstreams: 1 fakhoury_rs_me_bauru.pdf: 6525800 bytes, checksum: 924305300d1f4e62a2277a6beb1e313c (MD5) Previous issue date: 2018-04-06 / Utilizadas pelos arquitetos para apresentar seus projetos aos clientes, as imagens são um modo de representação capaz de externalizar ideias e pensamentos os tornando visíveis. A tecnologia vem sofrendo grandes transformações que ajudam a deixar o mundo digital cada vez mais próximo do mundo real. Portadoras de sentidos, as imagens tridimensionais (3D) digitais se autoexplicam aos clientes, não demandando mais uma visualização obrigatória das imagens bidimensionais (2D). Antes, elas eram uma base para que o processo projetual pudesse ocorrer e eram complementadas com informações em 3D. Hoje, o 2D é quem complementa o 3D, que se tornou requisito essencial para o entendimento do projeto pelos clientes, atuando como um meio de comunicação não-verbal. A presente dissertação teve como processo metodológico a realização de um estudo qualitativo, desenvolvido através de entrevistas com arquitetos e clientes e da execução de um roteiro de observação durante a reunião, analisando a explicação do arquiteto e a visualização do projeto pelos clientes. O foco principal foi obter resultados mais completos sobre a aplicação das imagens 3D digitais e seu modo de atuação como uma linguagem de comunicação visual servindo como um meio de auxílio na transferência de conhecimento e de ideias do arquiteto para o cliente, aumentando assim, seu entendimento e compreensão. / Used by architects to present their projects to clients, the images are a representation mode capable of externalizing ideas and thoughts making them visible. Technology has undergone major transformations that help to leave the digital world ever closer to the real world. Carriers of meanings, digital three-dimensional (3D) images are self-explanatory to clients, no longer requiring mandatory 2D imaging. Previously, they were a basis for the design process to occur and were complemented with 3D information. Today, 2D complements 3D, which has become an essential requirement for clients to understand the project, acting as a non-verbal communication way. The present dissertation had as methodological process the accomplishment of a qualitative study, developed through interviews with architects and clients and the execution of an itinerary of observation during the meeting, analyzing the explanation of the architect and the visualization of the project by the clients. The main focus was to obtain more complete results on the application of digital 3D images and their way of acting as a visual communication language serving as a means of aiding the transfer of knowledge and ideas from the architect to the client, thus increasing their understanding and comprehension.
225

O vôo virtual: metáfora e representação cartográfica tridimensional. / The virtual flight: metaphor and three-dimensional cartographic representation.

Alfredo Pereira de Queiroz Filho 11 May 2005 (has links)
A proposta deste trabalho é compreender o significado do vôo virtual, avaliar as características envolvidas e buscar rumos que ampliem sua utilidade. O vôo virtual é considerado como uma metáfora do deslocamento aéreo. Por meio de representações computacionais, permite variações seqüenciais de direção e de altitude sobre representações cartográficas tridimensionais. Caracteriza-se como uma interface flexível de apresentação de dados espaciais, que viabiliza a consulta dos seus atributos. O vôo possui um forte apelo visual, que une as características lúdicas dos jogos eletrônicos com o poder de atração das imagens de satélite. Permite o arranjo temático e temporal das informações mapeadas, aumenta as opções de representação (2 e 3D) e oferece uma visão integrada da superfície terrestre horizontal e vertical, proporcionada pelo sistema geocêntrico de coordenadas e pela pirâmide de múltipla resolução, que controla a variação de escala. / This work is prepared for the purposes of understanding the meaning of a virtual flight, to evaluate the characteristics involved and seek new ways to broaden its utility. A virtual flight is considered as a metaphor of air displacement. Through computerized representations, it enables sequential direction and altitude variations over three-dimensional cartographical representations. It is characterized as a flexible spatial data interface, which makes it possible to query its attributes. The flight has strong visual appeal, which combines the ludic characteristics of video games with the power of attraction of satellite images. It enables a thematic and temporal arrangement of mapped information, increases the options of representation (2 and 3D) and offers an integrated view of the land surface horizontal and vertical made possible through the geocentric system of coordinates and the multiple resolution pyramid, which controls the scale variation.
226

Robust and parallel mesh reconstruction from unoriented noisy points.

January 2009 (has links)
Sheung, Hoi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2009. / Includes bibliographical references (p. 65-70). / Abstract also in Chinese. / Abstract --- p.v / Acknowledgements --- p.ix / List of Figures --- p.xiii / List of Tables --- p.xv / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Main Contributions --- p.3 / Chapter 1.2 --- Outline --- p.3 / Chapter 2 --- Related Work --- p.5 / Chapter 2.1 --- Volumetric reconstruction --- p.5 / Chapter 2.2 --- Combinatorial approaches --- p.6 / Chapter 2.3 --- Robust statistics in surface reconstruction --- p.6 / Chapter 2.4 --- Down-sampling of massive points --- p.7 / Chapter 2.5 --- Streaming and parallel computing --- p.7 / Chapter 3 --- Robust Normal Estimation and Point Projection --- p.9 / Chapter 3.1 --- Robust Estimator --- p.9 / Chapter 3.2 --- Mean Shift Method --- p.11 / Chapter 3.3 --- Normal Estimation and Projection --- p.11 / Chapter 3.4 --- Moving Least Squares Surfaces --- p.14 / Chapter 3.4.1 --- Step 1: local reference domain --- p.14 / Chapter 3.4.2 --- Step 2: local bivariate polynomial --- p.14 / Chapter 3.4.3 --- Simpler Implementation --- p.15 / Chapter 3.5 --- Robust Moving Least Squares by Forward Search --- p.16 / Chapter 3.6 --- Comparison with RMLS --- p.17 / Chapter 3.7 --- K-Nearest Neighborhoods --- p.18 / Chapter 3.7.1 --- Octree --- p.18 / Chapter 3.7.2 --- Kd-Tree --- p.19 / Chapter 3.7.3 --- Other Techniques --- p.19 / Chapter 3.8 --- Principal Component Analysis --- p.19 / Chapter 3.9 --- Polynomial Fitting --- p.21 / Chapter 3.10 --- Highly Parallel Implementation --- p.22 / Chapter 4 --- Error Controlled Subsampling --- p.23 / Chapter 4.1 --- Centroidal Voronoi Diagram --- p.23 / Chapter 4.2 --- Energy Function --- p.24 / Chapter 4.2.1 --- Distance Energy --- p.24 / Chapter 4.2.2 --- Shape Prior Energy --- p.24 / Chapter 4.2.3 --- Global Energy --- p.25 / Chapter 4.3 --- Lloyd´ةs Algorithm --- p.26 / Chapter 4.4 --- Clustering Optimization and Subsampling --- p.27 / Chapter 5 --- Mesh Generation --- p.29 / Chapter 5.1 --- Tight Cocone Triangulation --- p.29 / Chapter 5.2 --- Clustering Based Local Triangulation --- p.30 / Chapter 5.2.1 --- Initial Surface Reconstruction --- p.30 / Chapter 5.2.2 --- Cleaning Process --- p.32 / Chapter 5.2.3 --- Comparisons --- p.33 / Chapter 5.3 --- Computing Dual Graph --- p.34 / Chapter 6 --- Results and Discussion --- p.37 / Chapter 6.1 --- Results of Mesh Reconstruction form Noisy Point Cloud --- p.37 / Chapter 6.2 --- Results of Clustering Based Local Triangulation --- p.47 / Chapter 7 --- Conclusions --- p.55 / Chapter 7.1 --- Key Contributions --- p.55 / Chapter 7.2 --- Factors Affecting Our Algorithm --- p.55 / Chapter 7.3 --- Future Work --- p.56 / Chapter A --- Building Neighborhood Table --- p.59 / Chapter A.l --- Building Neighborhood Table in Streaming --- p.59 / Chapter B --- Publications --- p.63 / Bibliography --- p.65
227

Recovering 3D geometry from single line drawings.

January 2011 (has links)
Xue, Tianfan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (p. 52-55). / Abstracts in English and Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Previous Approaches on Face Identification --- p.3 / Chapter 1.1.1 --- Face Identification --- p.3 / Chapter 1.1.2 --- General Objects --- p.4 / Chapter 1.1.3 --- Manifold Objects --- p.7 / Chapter 1.2 --- Previous Approaches on 3D Reconstruction --- p.9 / Chapter 1.3 --- Our approach for Face Identification --- p.11 / Chapter 1.4 --- Our approach for 3D Reconstruction --- p.13 / Chapter 2 --- Face Detection --- p.14 / Chapter 2.1 --- GAFI and its Face Identification Results --- p.15 / Chapter 2.2 --- Our Face Identification Approach --- p.17 / Chapter 2.2.1 --- Real Face Detection --- p.18 / Chapter 2.2.2 --- The Weak Face Adjacency Theorem --- p.20 / Chapter 2.2.3 --- Searching for Type 1 Lost Faces --- p.22 / Chapter 2.2.4 --- Searching for Type 2 Lost Faces --- p.23 / Chapter 2.3 --- Experimental Results --- p.25 / Chapter 3 3 --- D Reconstruction --- p.30 / Chapter 3.1 --- Assumption and Terminology --- p.30 / Chapter 3.2 --- Finding Cuts from a Line Drawing --- p.34 / Chapter 3.2.1 --- Propositions for Finding Cuts --- p.34 / Chapter 3.2.2 --- Searching for Good Cuts --- p.35 / Chapter 3.3 --- Separation of a Line Drawing from Cuts --- p.38 / Chapter 3.4 3 --- D Reconstruction from a Line Drawing --- p.45 / Chapter 3.5 --- Experiments --- p.45 / Chapter 4 --- Conclusion --- p.50
228

GPU-friendly marching cubes.

January 2008 (has links)
Xie, Yongming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 77-85). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.ii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Isosurfaces --- p.1 / Chapter 1.2 --- Graphics Processing Unit --- p.2 / Chapter 1.3 --- Objective --- p.3 / Chapter 1.4 --- Contribution --- p.3 / Chapter 1.5 --- Thesis Organization --- p.4 / Chapter 2 --- Marching Cubes --- p.5 / Chapter 2.1 --- Introduction --- p.5 / Chapter 2.2 --- Marching Cubes Algorithm --- p.7 / Chapter 2.3 --- Triangulated Cube Configuration Table --- p.12 / Chapter 2.4 --- Summary --- p.16 / Chapter 3 --- Graphics Processing Unit --- p.18 / Chapter 3.1 --- Introduction --- p.18 / Chapter 3.2 --- History of Graphics Processing Unit --- p.19 / Chapter 3.2.1 --- First Generation GPU --- p.20 / Chapter 3.2.2 --- Second Generation GPU --- p.20 / Chapter 3.2.3 --- Third Generation GPU --- p.20 / Chapter 3.2.4 --- Fourth Generation GPU --- p.21 / Chapter 3.3 --- The Graphics Pipelining --- p.21 / Chapter 3.3.1 --- Standard Graphics Pipeline --- p.21 / Chapter 3.3.2 --- Programmable Graphics Pipeline --- p.23 / Chapter 3.3.3 --- Vertex Processors --- p.25 / Chapter 3.3.4 --- Fragment Processors --- p.26 / Chapter 3.3.5 --- Frame Buffer Operations --- p.28 / Chapter 3.4 --- GPU CPU Analogy --- p.31 / Chapter 3.4.1 --- Memory Architecture --- p.31 / Chapter 3.4.2 --- Processing Model --- p.32 / Chapter 3.4.3 --- Limitation of GPU --- p.33 / Chapter 3.4.4 --- Input and Output --- p.34 / Chapter 3.4.5 --- Data Readback --- p.34 / Chapter 3.4.6 --- FramebufFer --- p.34 / Chapter 3.5 --- Summary --- p.35 / Chapter 4 --- Volume Rendering --- p.37 / Chapter 4.1 --- Introduction --- p.37 / Chapter 4.2 --- History of Volume Rendering --- p.38 / Chapter 4.3 --- Hardware Accelerated Volume Rendering --- p.40 / Chapter 4.3.1 --- Hardware Acceleration Volume Rendering Methods --- p.41 / Chapter 4.3.2 --- Proxy Geometry --- p.42 / Chapter 4.3.3 --- Object-Aligned Slicing --- p.43 / Chapter 4.3.4 --- View-Aligned Slicing --- p.45 / Chapter 4.4 --- Summary --- p.48 / Chapter 5 --- GPU-Friendly Marching Cubes --- p.49 / Chapter 5.1 --- Introduction --- p.49 / Chapter 5.2 --- Previous Work --- p.50 / Chapter 5.3 --- Traditional Method --- p.52 / Chapter 5.3.1 --- Scalar Volume Data --- p.53 / Chapter 5.3.2 --- Isosurface Extraction --- p.53 / Chapter 5.3.3 --- Flow Chart --- p.54 / Chapter 5.3.4 --- Transparent Isosurfaces --- p.56 / Chapter 5.4 --- Our Method --- p.56 / Chapter 5.4.1 --- Cell Selection --- p.59 / Chapter 5.4.2 --- Vertex Labeling --- p.61 / Chapter 5.4.3 --- Cell Indexing --- p.62 / Chapter 5.4.4 --- Interpolation --- p.65 / Chapter 5.5 --- Rendering Translucent Isosurfaces --- p.67 / Chapter 5.6 --- Implementation and Results --- p.69 / Chapter 5.7 --- Summary --- p.74 / Chapter 6 --- Conclusion --- p.76 / Bibliography --- p.77
229

Dynamic texture synthesis in image and video processing.

January 2008 (has links)
Xu, Leilei. / Thesis submitted in: October 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 78-84). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Texture and Dynamic Textures --- p.1 / Chapter 1.2 --- Related work --- p.4 / Chapter 1.3 --- Thesis Outline --- p.7 / Chapter 2 --- Image/Video Processing --- p.8 / Chapter 2.1 --- Bayesian Analysis --- p.8 / Chapter 2.2 --- Markov Property --- p.10 / Chapter 2.3 --- Graph Cut --- p.12 / Chapter 2.4 --- Belief Propagation --- p.13 / Chapter 2.5 --- Expectation-Maximization --- p.15 / Chapter 2.6 --- Principle Component Analysis --- p.15 / Chapter 3 --- Linear Dynamic System --- p.17 / Chapter 3.1 --- System Model --- p.18 / Chapter 3.2 --- Degeneracy and Canonical Model Realization --- p.19 / Chapter 3.3 --- Learning of Dynamic Textures --- p.19 / Chapter 3.4 --- Synthesizing Dynamic Textures --- p.21 / Chapter 3.5 --- Summary --- p.21 / Chapter 4 --- Dynamic Color Texture Synthesis --- p.25 / Chapter 4.1 --- Related Work --- p.25 / Chapter 4.2 --- System Model --- p.26 / Chapter 4.2.1 --- Laplacian Pyramid-based DCTS Model --- p.28 / Chapter 4.2.2 --- RBF-based DCTS Model --- p.28 / Chapter 4.3 --- Experimental Results --- p.32 / Chapter 4.4 --- Summary --- p.42 / Chapter 5 --- Dynamic Textures using Multi-resolution Analysis --- p.43 / Chapter 5.1 --- System Model --- p.44 / Chapter 5.2 --- Multi-resolution Descriptors --- p.46 / Chapter 5.2.1 --- Laplacian Pyramids --- p.47 / Chapter 5.2.2 --- Haar Wavelets --- p.48 / Chapter 5.2.3 --- Steerable Pyramid --- p.49 / Chapter 5.3 --- Experimental Results --- p.51 / Chapter 5.4 --- Summary --- p.55 / Chapter 6 --- Motion Transfer --- p.59 / Chapter 6.1 --- Problem formulation --- p.60 / Chapter 6.1.1 --- Similarity on Appearance --- p.61 / Chapter 6.1.2 --- Similarity on Dynamic Behavior --- p.62 / Chapter 6.1.3 --- The Objective Function --- p.65 / Chapter 6.2 --- Further Work --- p.66 / Chapter 7 --- Conclusions --- p.67 / Chapter A --- List of Publications --- p.68 / Chapter B --- Degeneracy in LDS Model --- p.70 / Chapter B.l --- Equivalence Class --- p.70 / Chapter B.2 --- The Choice of the Matrix Q --- p.70 / Chapter B.3 --- Swapping the Column of C and A --- p.71 / Chapter C --- Probability Density Functions --- p.74 / Chapter C.1 --- Probability Distribution --- p.74 / Chapter C.2 --- Joint Probability Distributions --- p.75 / Bibliography --- p.78
230

3D visibility analysis for visual quality assessment: approaches based on modelling tools, VGE and WebGIS / CUHK electronic theses & dissertations collection

January 2016 (has links)
In this thesis, the author has explored the feasibility of 3D visibility analysis for visual quality assessment via the aid of modelling tools, virtual geographic environment (VGE) and WebGIS, which may be beneficial to build a measurable evaluating standard of visual environment in urban open spaces, and referential to create an atmosphere with improved visual comfort in guiding planning or design processing. Considered as long-term significance, 3D visibility analysis for visual quality assessment is potential in enabling the quantitative analysis between urban open spaces and visual perception of human, providing appropriate standard for evaluation of visual environment, and bringing the future urban planning and design fields into rational and reasonable. / Due to the development of 3D modelling software and VGE, their applications have been attempted in 3D visibility analysis by a few previous scholars, exploring the possibility of representation for urban environment in 3D and the feasibility of spatial relationship analysis with visual factors. Lots of progress has been made with the participation of the modelling software such as AutoCAD and 3Ds Max, or analytical platforms such as ArcGIS and VGE. As the extension of preceding study, the author is going to discuss improvements and innovations of some tools applied in visibility analysis and visual quality computation, such as Open Simulator as a VGE Platform. Moreover, due to the easy access for entry-level programmer and the public, Google SketchUp (a type of modelling software) and WebGIS have also been tested whether suitable for the analysis handling, considerably decreasing the programming development difficulty. Both SketchUp and WebGIS are thought to be well accepted by thepublic, as SketchUp has been popularised in 3D modelling and WebGIS has been familiar as the form of websites for a long period, which may enable the dissemination of visibility analysis to the public. / From a pilot study of progresses based on the researches of past scholars, the author developed an improved method for 3D visibility analysis, by mathematically deriving the visual factors from the spatial relationship analysis of buildings, terrain and other geographical features. A few quantitative factors as the distance, solid angle and visual field (a distribution of occupied solid angle in all directions) valued in spherical coordinate system were adopted as the basic units for visibility levels. Starting from the space prototype, the research has also focused on several aspects possibly associated to the visual effects in open spaces, including the openness, enclosure and ground coverage for edge, the distribution and dispersion for skyline, and the visibility of individual building for landmark. For further comparison, the variances of those figures were also noticed during space scales changing for the prototype, in order to find possible connection or changing trend before and after. Moreover, experiments of 3D visibility analysis have been designed and put into practice for real scenes to discover the similarities or differences among prototypical spaces and reality, and Piazza del Campo (Siena, Italy), Piazza San Marco (Venice, Italy) and Olomouc centre area (Olomouc, Czech) have been selected as the first group of candidates. As a complementary study, the central campus area of the Chinese University of Hong Kong (CUHK) were also taken into consideration as an experimental site, for comparison of disparities with those classical scenes. Those would be possible references for conclusion of similarity or discrepancy among various spaces, in order to find out spatial general pattern, or reveal the actual affections of visual factor values in the reality. / 在本論文中,作者基於建模工具、虛擬地理環境和网络地理信息系統(WebGIS),對三維可視性分析和視覺評估的可行性進行了探討。概括而言,這項探討將有助於在城市開放空間可評估測量屬性的輔助下實施城市規劃和設計,以期打造具有更佳視覺舒適性的城市環境。而從長遠意義上考量,三維可視性分析和視覺評估亦是實現城市開放空間和視覺感知之間聯繫的定量分析前提,並為城市環境評價提供適當標準,使今後的規劃和設計更趨理性。 / 由於三維建模軟件和虛擬地理環境的發展,部分學者已在三維可視性分析中進行些許嘗試,試圖了解在城市環境中的三維空間關係與視覺因素進行相關分析的可行性。且在此研究之前,部分實驗已於個別建模軟件如AutoCAD和3ds Max、或分析平台如ArcGIS和虛擬地理環境中取得可觀進展。基於以上前人的成就,筆者一方面期望在分析工具上進行適度革新,另一方面追尋可視性分析和視覺評估算法上改進的可能,從而在本文中做出個人領域上的創新。在此之中,考慮到入門難易程度和公眾接納程度,筆者採納了若干開發難度較低的工具相互搭配,如谷歌草图大师(Google SketchUp,一種輕量級建模軟件)、Open Simulator(虛擬地擬環境平台)和网络地理信息系統,來輔助進行城市開放空間的可視性分析。谷歌草图大师常被用作於平民化的三維建模,Open Simulator可提供形象化的現實模擬和交互環境,而WebGIS以眾人熟知的網站形式進行交互操作,這些工具在大眾中擁有較高的普及程度和較低的接納門檻,同時亦為可視性分析在大眾中普及提供了一定的可能。 / 而從三維可視性分析的方法改進上,筆者基於先前學者的部分試點研究,在數學推導上對地形、建築物等地理特徵產生空間關係的計算方法提供合理改進。基於球坐標系,作者用距離、球面度和視角分佈(各方向上視角的分佈)等量化數值為城市開放空間進行基本可視單元的度量;亦從空間原型出發,研究集中討論了若干視覺效果,如開放度、圍合度和地面覆蓋度,天際線的分佈和離散程度,個別建築物的可視性分佈等,在城市開放空間可視效果度量上的作用。此外,通過進一步比較各空間之間可視數值上的差異,量化地去理解空間的視覺效果差異,並可依照參數變化的對比尋找可能存在的變化趨勢和相關性,對空間的可視性有更深的理解。 / 在本論文的實驗中,作者亦採用了部分真實場景進行三維可視性和視覺評估的分析,以期發現與原型空間相似性或差異性。坎波廣場(意大利錫耶納)、聖馬可廣場(意大利威尼斯)和奧洛穆茨中心區域(捷克奧洛穆茨)作為城市經典空間作為第一批實驗場景,而後續的香港中文大學中央校園作為普通場景的對比亦被納入實驗場景之中,以便進行相似性和差異性的探討。採用真實場景的實驗有助於更好地將現實中城市開放空間的視覺特性與演算結果進行結合,揭示各可視數值的實際表現意義,並在空間原型的相似性上進行合理探討。 / Lin, Tianpeng. / Thesis Ph.D. Chinese University of Hong Kong 2016. / Includes bibliographical references (leaves 110-116). / Abstracts also in Chinese. / Title from PDF title page (viewed on 05, October, 2016). / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only.

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