by Lai Hin Lun. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 54-57). / Abstracts in English and Chinese. / Abstract --- p.i / Acknowledgement --- p.iv / Table of Contents --- p.v / List of Figures --- p.vii / Chapter Chapter 1 --- Introduction --- p.1 / Chapter Chapter 2 --- Related Works --- p.8 / Chapter 2.1 --- Source Modeling --- p.9 / Chapter 2.2 --- CBR Scheduler for VBR Delivery --- p.11 / Chapter 2.3 --- Brute Force Scheduler: --- p.15 / Chapter 2.4 --- Temporal Smoothing Scheduler: --- p.16 / Chapter Chapter 3 --- Decreasing Rate Scheduling --- p.22 / Chapter 3.1 --- MDRS with Minimum Buffer Requirement --- p.25 / Chapter 3.2 --- 2-Rate MDRS --- p.31 / Chapter Chapter 4 --- Performance Evaluation --- p.33 / Chapter 4.1 --- Buffer Requirement --- p.35 / Chapter 4.2 --- Startup Delay --- p.38 / Chapter 4.3 --- Disk Utilization --- p.39 / Chapter 4.4 --- Complexity --- p.43 / Chapter Chapter 5 --- Conclusion --- p.49 / Appendix --- p.51 / Bibliography --- p.54

Cheung Man-kin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 116-120). / Abstracts in English and Chinese. / Chapter 1) --- Introduction --- p.1 / Chapter 1.1) --- Building of the 3D Wireframe and Facial Model --- p.2 / Chapter 1.2) --- Description of 3D Model Based Video Conferencing --- p.3 / Chapter 1.3) --- Wireframe Model Fitting or Conformation --- p.6 / Chapter 1.4) --- Pose Estimation --- p.8 / Chapter 1.5) --- Facial Motion Estimation and Synthesis --- p.9 / Chapter 1.6) --- Thesis Outline --- p.10 / Chapter 2) --- Wireframe model Fitting --- p.11 / Chapter 2.1) --- Algorithm of WFM Fitting --- p.12 / Chapter 2.1.1) --- Global Deformation --- p.14 / Chapter a) --- Scaling --- p.14 / Chapter b) --- Shifting --- p.15 / Chapter 2.1.2) --- Local Deformation --- p.15 / Chapter a) --- Shifting --- p.16 / Chapter b) --- Scaling --- p.17 / Chapter 2.1.3) --- Fine Updating --- p.17 / Chapter 2.2) --- Steps of Fitting --- p.18 / Chapter 2.3) --- Functions of Different Deformation --- p.18 / Chapter 2.4) --- Experimental Results --- p.19 / Chapter 2.4.1) --- Output wireframe in each step --- p.19 / Chapter 2.4.2) --- Examples of Mis-fitted wireframe with incoming image --- p.22 / Chapter 2.4.3) --- Fitted 3D facial wireframe --- p.23 / Chapter 2.4.4) --- Effect of mis-fitted wireframe after compensation of motion --- p.24 / Chapter 2.5) --- Summary --- p.26 / Chapter 3) --- Epipolar Geometry --- p.27 / Chapter 3.1) --- Pinhole Camera Model and Perspective Projection --- p.28 / Chapter 3.2) --- Concepts in Epipolar Geometry --- p.31 / Chapter 3.2.1) --- Working with normalized image coordinates --- p.33 / Chapter 3.2.2) --- Working with pixel image coordinates --- p.35 / Chapter 3.2.3) --- Summary --- p.37 / Chapter 3.3) --- 8-point Algorithm (Essential and Fundamental Matrix) --- p.38 / Chapter 3.3.1) --- Outline of the 8-point algorithm --- p.38 / Chapter 3.3.2) --- Modification on obtained Fundamental Matrix --- p.39 / Chapter 3.3.3) --- Transformation of Image Coordinates --- p.40 / Chapter a) --- Translation to mean of points --- p.40 / Chapter b) --- Normalizing transformation --- p.41 / Chapter 3.3.4) --- Summary of 8-point algorithm --- p.41 / Chapter 3.4) --- Estimation of Object Position by Decomposition of Essential Matrix --- p.43 / Chapter 3.4.1) --- Algorithm Derivation --- p.43 / Chapter 3.4.2) --- Algorithm Outline --- p.46 / Chapter 3.5) --- Noise Sensitivity --- p.48 / Chapter 3.5.1) --- Rotation vector of model --- p.48 / Chapter 3.5.2) --- The projection of rotated model --- p.49 / Chapter 3.5.3) --- Noisy image --- p.51 / Chapter 3.5.4) --- Summary --- p.51 / Chapter 4) --- Pose Estimation --- p.54 / Chapter 4.1) --- Linear Method --- p.55 / Chapter 4.1.1) --- Theory --- p.55 / Chapter 4.1.2) --- Normalization --- p.57 / Chapter 4.1.3) --- Experimental Results --- p.58 / Chapter a) --- Synthesized image by linear method without normalization --- p.58 / Chapter b) --- Performance between linear method with and without normalization --- p.60 / Chapter c) --- Performance of linear method under quantization noise with different transformation components --- p.62 / Chapter d) --- Performance of normalized case without transformation in z- component --- p.63 / Chapter 4.1.4) --- Summary --- p.64 / Chapter 4.2) --- Two Stage Algorithm --- p.66 / Chapter 4.2.1) --- Introduction --- p.66 / Chapter 4.2.2) --- The Two Stage Algorithm --- p.67 / Chapter a) --- Stage 1 (Iterative Method) --- p.68 / Chapter b) --- Stage 2 ( Non-linear Optimization) --- p.71 / Chapter 4.2.3) --- Summary of the Two Stage Algorithm --- p.72 / Chapter 4.2.4) --- Experimental Results --- p.72 / Chapter 4.2.5) --- Summary --- p.80 / Chapter 5) --- Facial Motion Estimation and Synthesis --- p.81 / Chapter 5.1) --- Facial Expression based on face muscles --- p.83 / Chapter 5.1.1) --- Review of Action Unit Approach --- p.83 / Chapter 5.1.2) --- Distribution of Motion Unit --- p.85 / Chapter 5.1.3) --- Algorithm --- p.89 / Chapter a) --- For Unidirectional Motion Unit --- p.89 / Chapter b) --- For Circular Motion Unit (eyes) --- p.90 / Chapter c) --- For Another Circular Motion Unit (mouth) --- p.90 / Chapter 5.1.4) --- Experimental Results --- p.91 / Chapter 5.1.5) --- Summary --- p.95 / Chapter 5.2) --- Detection of Facial Expression by Muscle-based Approach --- p.96 / Chapter 5.2.1) --- Theory --- p.96 / Chapter 5.2.2) --- Algorithm --- p.97 / Chapter a) --- For Sheet Muscle --- p.97 / Chapter b) --- For Circular Muscle --- p.98 / Chapter c) --- For Mouth Muscle --- p.99 / Chapter 5.2.3) --- Steps of Algorithm --- p.100 / Chapter 5.2.4) --- Experimental Results --- p.101 / Chapter 5.2.5) --- Summary --- p.103 / Chapter 6) --- Conclusion --- p.104 / Chapter 6.1) --- WFM fitting --- p.104 / Chapter 6.2) --- Pose Estimation --- p.105 / Chapter 6.3) --- Facial Estimation and Synthesis --- p.106 / Chapter 6.4) --- Discussion on Future Improvements --- p.107 / Chapter 6.4.1) --- WFM Fitting --- p.107 / Chapter 6.4.2) --- Pose Estimation --- p.109 / Chapter 6.4.3) --- Facial Motion Estimation and Synthesis --- p.110 / Chapter 7) --- Appendix --- p.111 / Chapter 7.1) --- Newton's Method or Newton-Raphson Method --- p.111 / Chapter 7.2) --- H.261 --- p.113 / Chapter 7.3) --- 3D Measurement --- p.114 / Bibliography --- p.116

Lee Kar Kin Edwin. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 129-134). / Text in English; abstracts in English and Chinese. / Lee Kar Kin Edwin. / Acknowledgement --- p.ii / Abstract --- p.iii / Contents --- p.vii / List of Figures --- p.ix / List of Tables --- p.xiii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- A brief review of transform-based video coding --- p.1 / Chapter 1.2 --- A brief review of content-based video coding --- p.6 / Chapter 1.3 --- Objectives of the research work --- p.9 / Chapter 1.4 --- Thesis outline --- p.12 / Chapter 2 --- Incorporation of DC Coefficient Restoration into Foreground/Background coding --- p.13 / Chapter 2.1 --- Introduction --- p.13 / Chapter 2.2 --- A review of FB coding in H.263 sequence --- p.15 / Chapter 2.3 --- A review of DCCR --- p.18 / Chapter 2.4 --- DCCRFB coding --- p.23 / Chapter 2.4.1 --- Methodology --- p.23 / Chapter 2.4.2 --- Implementation --- p.24 / Chapter 2.4.3 --- Experimental results --- p.26 / Chapter 2.5 --- The use of block selection scheme in DCCRFB coding --- p.32 / Chapter 2.5.1 --- Introduction --- p.32 / Chapter 2.5.2 --- Experimental results --- p.34 / Chapter 2.6 --- Summary --- p.47 / Chapter 3 --- Chin contour estimation on foreground human faces --- p.48 / Chapter 3.1 --- Introduction --- p.48 / Chapter 3.2 --- Least mean square estimation of chin location --- p.50 / Chapter 3.3 --- Chin contour estimation using chin edge detector and contour modeling --- p.58 / Chapter 3.3.1 --- Face segmentation and facial organ extraction --- p.59 / Chapter 3.3.2 --- Identification of search window --- p.59 / Chapter 3.3.3 --- Edge detection using chin edge detector --- p.60 / Chapter 3.3.4 --- "Determination of C0, C1 and c2" --- p.63 / Chapter 3.3.5 --- Chin contour modeling --- p.67 / Chapter 3.4 --- Experimental results --- p.71 / Chapter 3.5 --- Summary --- p.77 / Chapter 4 --- Wire-frame model deformation and face animation using FAP --- p.78 / Chapter 4.1 --- Introduction --- p.78 / Chapter 4.2 --- Wire-frame face model deformation --- p.79 / Chapter 4.2.1 --- Introduction --- p.79 / Chapter 4.2.2 --- Wire-frame model selection and FDP generation --- p.81 / Chapter 4.2.3 --- Global deformation --- p.85 / Chapter 4.2.4 --- Local deformation --- p.87 / Chapter 4.2.5 --- Experimental results --- p.93 / Chapter 4.3 --- Face animation using FAP --- p.98 / Chapter 4.3.1 --- Introduction and methodology --- p.98 / Chapter 4.3.2 --- Experiments --- p.102 / Chapter 4.4 --- Summary --- p.112 / Chapter 5 --- Conclusions and future developments --- p.113 / Chapter 5.1 --- Contributions and conclusions --- p.113 / Chapter 5.2 --- Future developments --- p.117 / Appendix A H.263 bitstream syntax --- p.122 / Appendix B Excerpt of the FAP specification table [17] --- p.123 / Bibliography --- p.129

by Lam Cheung Fai. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 174-179). / Abstract also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Problem Definition --- p.2 / Chapter 1.2 --- Motivation --- p.5 / Chapter 1.3 --- Problems --- p.7 / Chapter 1.3.1 --- Illumination Changes and Motions in Videos --- p.7 / Chapter 1.3.2 --- Variations in Video Scene Characteristics --- p.8 / Chapter 1.3.3 --- High Complexity of Algorithms --- p.10 / Chapter 1.3.4 --- Heterogeneous Approaches to Video Segmentation --- p.10 / Chapter 1.4 --- Objectives and Approaches --- p.11 / Chapter 1.5 --- Organization of the Thesis --- p.13 / Chapter 2 --- Related Work --- p.15 / Chapter 2.1 --- Algorithms for Uncompressed Videos --- p.16 / Chapter 2.1.1 --- Pixel-based Method --- p.16 / Chapter 2.1.2 --- Histogram-based Method --- p.17 / Chapter 2.1.3 --- Motion-based Algorithms --- p.18 / Chapter 2.1.4 --- Color-ratio Based Algorithms --- p.18 / Chapter 2.2 --- Algorithms for Compressed Videos --- p.19 / Chapter 2.2.1 --- Algorithms based on JPEG Image Sequences --- p.19 / Chapter 2.2.2 --- Algorithms based on MPEG Videos --- p.20 / Chapter 2.2.3 --- Algorithms based on VQ Compressed Videos --- p.21 / Chapter 2.3 --- Frame Difference Analysis Methods --- p.21 / Chapter 2.3.1 --- Scene Cut Detection --- p.21 / Chapter 2.3.2 --- Gradual Transition Detection --- p.22 / Chapter 2.4 --- Speedup Techniques --- p.23 / Chapter 2.5 --- Other Approaches --- p.24 / Chapter 3 --- Analysis and Enhancement of Existing Algorithms --- p.25 / Chapter 3.1 --- Introduction --- p.25 / Chapter 3.2 --- Video Segmentation Algorithms --- p.26 / Chapter 3.2.1 --- Frame Difference Metrics --- p.26 / Chapter 3.2.2 --- Frame Difference Analysis Methods --- p.29 / Chapter 3.3 --- Analysis of Feature Extraction Algorithms --- p.30 / Chapter 3.3.1 --- Pair-wise pixel comparison --- p.30 / Chapter 3.3.2 --- Color histogram comparison --- p.34 / Chapter 3.3.3 --- Pair-wise block-based comparison of DCT coefficients --- p.38 / Chapter 3.3.4 --- Pair-wise pixel comparison of DC-images --- p.42 / Chapter 3.4 --- Analysis of Scene Change Detection Methods --- p.45 / Chapter 3.4.1 --- Global Threshold Method --- p.45 / Chapter 3.4.2 --- Sliding Window Method --- p.46 / Chapter 3.5 --- Enhancements and Modifications --- p.47 / Chapter 3.5.1 --- Histogram Equalization --- p.49 / Chapter 3.5.2 --- DD Method --- p.52 / Chapter 3.5.3 --- LA Method --- p.56 / Chapter 3.5.4 --- Modification for pair-wise pixel comparison --- p.57 / Chapter 3.5.5 --- Modification for pair-wise DCT block comparison --- p.61 / Chapter 3.6 --- Conclusion --- p.69 / Chapter 4 --- Color Difference Histogram --- p.72 / Chapter 4.1 --- Introduction --- p.72 / Chapter 4.2 --- Color Difference Histogram --- p.73 / Chapter 4.2.1 --- Definition of Color Difference Histogram --- p.73 / Chapter 4.2.2 --- Sparse Distribution of CDH --- p.76 / Chapter 4.2.3 --- Resolution of CDH --- p.77 / Chapter 4.2.4 --- CDH-based Inter-frame Similarity Measure --- p.77 / Chapter 4.2.5 --- Computational Cost and Discriminating Power --- p.80 / Chapter 4.2.6 --- Suitability in Scene Change Detection --- p.83 / Chapter 4.3 --- Insensitivity to Illumination Changes --- p.89 / Chapter 4.3.1 --- Sensitivity of CDH --- p.90 / Chapter 4.3.2 --- Comparison with other feature extraction algorithms --- p.93 / Chapter 4.4 --- Orientation and Motion Invariant --- p.96 / Chapter 4.4.1 --- Camera Movements --- p.97 / Chapter 4.4.2 --- Object Motion --- p.100 / Chapter 4.4.3 --- Comparison with other feature extraction algorithms --- p.100 / Chapter 4.5 --- Performance of Scene Cut Detection --- p.102 / Chapter 4.6 --- Time Complexity Comparison --- p.105 / Chapter 4.7 --- Extension to DCT-compressed Images --- p.106 / Chapter 4.7.1 --- Performance of scene cut detection --- p.108 / Chapter 4.8 --- Conclusion --- p.109 / Chapter 5 --- Scene Change Detection --- p.111 / Chapter 5.1 --- Introduction --- p.111 / Chapter 5.2 --- Previous Approaches --- p.112 / Chapter 5.2.1 --- Scene Cut Detection --- p.112 / Chapter 5.2.2 --- Gradual Transition Detection --- p.115 / Chapter 5.3 --- DD Method --- p.116 / Chapter 5.3.1 --- Detecting Scene Cuts --- p.117 / Chapter 5.3.2 --- Detecting 1-frame Transitions --- p.121 / Chapter 5.3.3 --- Detecting Gradual Transitions --- p.129 / Chapter 5.4 --- Local Thresholding --- p.131 / Chapter 5.5 --- Experimental Results --- p.134 / Chapter 5.5.1 --- Performance of CDH+DD and CDH+DL --- p.135 / Chapter 5.5.2 --- Performance of DD on other features --- p.144 / Chapter 5.6 --- Conclusion --- p.150 / Chapter 6 --- Motion Vector Based Approach --- p.151 / Chapter 6.1 --- Introduction --- p.151 / Chapter 6.2 --- Previous Approaches --- p.152 / Chapter 6.3 --- MPEG-I Video Stream Format --- p.153 / Chapter 6.4 --- Derivation of Frame Differences from Motion Vector Counts --- p.156 / Chapter 6.4.1 --- Types of Frame Pairs --- p.156 / Chapter 6.4.2 --- Conditions for Scene Changes --- p.157 / Chapter 6.4.3 --- Frame Difference Measure --- p.159 / Chapter 6.5 --- Experiment --- p.160 / Chapter 6.5.1 --- Performance of MV --- p.161 / Chapter 6.5.2 --- Performance Enhancement --- p.162 / Chapter 6.5.3 --- Limitations --- p.163 / Chapter 6.6 --- Conclusion --- p.164 / Chapter 7 --- Conclusion and Future Work --- p.165 / Chapter 7.1 --- Contributions --- p.165 / Chapter 7.2 --- Future Work --- p.169 / Chapter 7.3 --- Conclusion --- p.171 / Bibliography --- p.174 / Chapter A --- Sample Videos --- p.180 / Chapter B --- List of Abbreviations --- p.183

by Cheng Shu Ling. / Thesis submitted in: July 1997. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1998. / Includes bibliographical references (leaves 70-71). / Abstract also in Chinese. / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Image Coding Standard: JPEG --- p.1 / Chapter 1.2 --- Video Coding Standard: MPEG --- p.6 / Chapter 1.2.1 --- MPEG history --- p.6 / Chapter 1.2.2 --- MPEG video compression algorithm overview --- p.8 / Chapter 1.2.3 --- More MPEG features --- p.10 / Chapter 1.3 --- Summary --- p.17 / Chapter Chapter 2 --- Error Resiliency --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Traditional approaches --- p.19 / Chapter 2.2.1 --- Channel coding --- p.19 / Chapter 2.2.2 --- ARQ --- p.20 / Chapter 2.2.3 --- Multi-layer coding --- p.20 / Chapter 2.2.4 --- Error Concealment --- p.20 / Chapter 2.3 --- MPEG-4 work on error resilience --- p.21 / Chapter 2.3.1 --- Resynchronization --- p.21 / Chapter 2.3.2 --- Data Recovery --- p.25 / Chapter 2.3.3 --- Error Concealment --- p.28 / Chapter 2.4 --- Summary --- p.29 / Chapter Chapter 3 --- Fixed length codes --- p.30 / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Tunstall code --- p.31 / Chapter 3.3 --- Lempel-Ziv code --- p.34 / Chapter 3.3.1 --- LZ-77 --- p.35 / Chapter 3.3.2 --- LZ-78 --- p.36 / Chapter 3.4 --- Simulation --- p.38 / Chapter 3.4.1 --- Experiment Setup --- p.38 / Chapter 3.4.2 --- Results --- p.39 / Chapter 3.4.3 --- Concluding Remarks --- p.42 / Chapter Chapter 4 --- Self-Synchronizable codes --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- Scholtz synchronizable code --- p.45 / Chapter 4.2.1 --- Definition --- p.45 / Chapter 4.2.2 --- Construction procedure --- p.45 / Chapter 4.2.3 --- Synchronizer --- p.48 / Chapter 4.2.4 --- Effects of errors --- p.51 / Chapter 4.3 --- Simulation --- p.52 / Chapter 4.3.1 --- Experiment Setup --- p.52 / Chapter 4.3.2 --- Results --- p.56 / Chapter 4.4 --- Concluding Remarks --- p.68 / Chapter Chapter 5 --- Conclusions --- p.69 / References --- p.70

随着3D 图形学技术的快速发展，基于细分小波的多分辨率方法受到了越来越多的关注。为了提高运算效率， 一些细分小波采用了厅局部提升用的方法以避免解全局方程组的庞大开销。这种方法虽然极大地提高了小波分解的速度，但也使得这些小波较之一些经典的细分小波在生成曲面的质量上有所不如。在本篇论文里，我们提出了一组新型细分小波。这些小波变换不但保留了"局部提升"波运算速度快，节省内存的优点，在生成模型的质量上也大大提高，接近了经典的全局优化小波。 / 我们构造了极细分小波用于极结构快速简化和重构。极细分小波变换有效地避免Catmull -Clark 细分小波用于极结构时所造成的"皱裙"和鞍点，可以在高度数的异常点区域生成非常自然的二次连续曲面。为了更好的应用于普通的四边形网格曲面，我们还改进了极细分小波使之生成的曲面可以在边界处与Catmull-Clark 细分小波曲面光滑地融合。实验表明我们构造的混合极细分小波不但运算效率高，节省内存，还具有良好的稳定性，生成的曲面质量良好。基于矩阵值细分，我们还构造了一组近似和插值类型的矩阵值小波。由于矩阵值小波变换直接作用于向量，我们可以利用向量中额外的项作为参数以控制生成的多分辨率由面的形状。通过优化这些形状控制参数，我们在保持高效低内存消耗的同时，还可以进一步提高"局部提升"小波曲面的质量。 / 我们还将矩阵值小波应用于3D 模型的几何压缩。为了避免存储形状控制参数所带来的额外消耗，我们采用固定的形状控制参数从而将矩阵值小波简化为一种特殊的标量值小波。实验表明采用我们的小波的压缩方法，其压缩率接近于经典的全局优化小波，远高于"局部提升"小波。其压缩速度则接近于"局部提升"小波，远高于经典的采用全局优化小波。在未来的研究工作中，我们会进一步优化形状控制参数的选择策略，并尝试将其应用范围从目前三角形网格由面扩展到四边形曲面， T 样条曲面以及混合曲面。我们还将研究如何应用己有的小波变换提高多分辨率编辑与动画技术。 / During the rapid development of 3D graphics applications, the wavelet-based multiresolution approaches have attracted more attention because they can effectively reduce the process/storage costs of high-detailed models. For the efficiency, many wavelets are constructed by using local lifting, which makes the fitting quality of results are not good as the usual wavelets with global optimization. On the other hand, once the wavelet transforms were constructed, the multiresolution meshes got by them cannot be adjusted any more. It is important to develop the new adaptive wavelets with better fitting quality, while keeping the high efficiency. In this dissertation, we provide several secondgeneration wavelets with improved fitting qualities, which include the compound biorthogonal wavelets for the hybrid quadrilateral meshes, and the efficient matrix-valued wavelets for complex triangular meshes. / We propose the novel polar subdivision wavelet, which efficiently generate multiresolution the polar structures. Polar structures are the natural representations of the self-revolution structures or high-valence regions of quadrilateral grids. The traditional multiresolution methods for the polar structures often generate deficits caused by high valence vertices. By adopting the polar subdivision and the special lifting operations on the polar structures, our wavelet transforms can generate smooth multiresolution surfaces without ripples and saddle points. To process the hybrid meshes made of quadrilaterals and polar structures, we extend the polar wavelet to the vertices in the circular layers, which makes it possible to fuse the surfaces generated by different wavelet transforms seamlessly. To improve the fitting quality of local lifting wavelets, we extend wavelet constructions from the scalar-valued scheme to the matrix-valued scheme, and propose a family of novel approximate and interpolatory matrix-valued subdivision wavelets. The matrix-valued wavelets are constructed from the refinable basis function vectors, which deal with the additional parameters to the geometric position of vertices. Since the final results of wavelet transforms are sensitive to the parameters, these parameters can be used to adjust the shape of multiresolution surfaces. By applying the lifting scheme, the computations of wavelet transform are local and in-placed. We also discuss the strategy of better shape controls for improving the fitting quality of simplified surfaces. The experiments showed that these novel wavelet transforms were sufficiently stable and performed well for noise reduction. With the suitable shape control parameters, the fitting quality of multiresolution surfaces can be further improved. / We study how to apply the efficient compression approach to the real applications, such as the compression of meshes. Since the shape control parameters need the additional storage, they will decrease the compression ratio if we apply the original versions of matrix-valued wavelets. We revise the construction of the matrix-valued wavelet transform and proposed the parameterized scalar-valued wavelet transform. With the special optimization of wavelet construction and suitable parameters, our compression approach has the high compression ratio close to the well-known approaches using the global orthogonal wavelets, and much higher compression ratio than the compression using the local lifting wavelets, while keeping the good efficiency. In the future work, we plan to extend the matrix-valued wavelets from triangular meshes to quadrilateral, normal and hybrid meshes. We will study how to apply the matrix-valued wavelets to the applications, such as multiresolution editing and animations. Further optimization of the shape control parameters for mobile and online applications is also an important issue. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhao, Chong. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 136-149). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / Acknowledgement --- p.v / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Wavelet Transform --- p.4 / Chapter 1.2.1 --- Wavelets and Multiresolution Analysis --- p.4 / Chapter 1.2.2 --- Continuous Wavelet Transforms --- p.7 / Chapter 1.2.3 --- Discrete Wavelet Transform --- p.8 / Chapter 1.3 --- Second Generation Wavelets --- p.9 / Chapter 1.3.1 --- Lifting Scheme --- p.9 / Chapter 1.3.2 --- Subdivision --- p.11 / Chapter 1.3.3 --- Subdivision Wavelets --- p.13 / Chapter 1.4 --- Main Contributions --- p.15 / Chapter 1.5 --- Chapter Summary --- p.16 / Chapter 2 --- Compound Wavelets on Quadrilaterals --- p.18 / Chapter 2.1 --- Introduction --- p.18 / Chapter 2.2 --- Related Work --- p.19 / Chapter 2.3 --- Polar Subdivision --- p.20 / Chapter 2.3.1 --- Subdivision in radial layers --- p.21 / Chapter 2.3.2 --- Subdivision in circular layers --- p.24 / Chapter 2.4 --- Subdivision Wavelets Using Lifting --- p.25 / Chapter 2.4.1 --- Lifting wavelets --- p.25 / Chapter 2.4.2 --- Wavelet transforms --- p.29 / Chapter 2.5 --- Compound Subdivision Wavelets --- p.32 / Chapter 2.6 --- Experimental Results --- p.34 / Chapter 2.7 --- Chapter Summary --- p.38 / Chapter 3 --- Matrix-valued Loop Wavelets --- p.40 / Chapter 3.1 --- Introduction --- p.40 / Chapter 3.2 --- Related Work --- p.41 / Chapter 3.3 --- Matrix-valued Loop Subdivision --- p.43 / Chapter 3.4 --- Matrix-valued Loop Subdivision Wavelet --- p.46 / Chapter 3.4.1 --- Lazy Wavelet --- p.46 / Chapter 3.4.2 --- Inner Product --- p.49 / Chapter 3.4.3 --- Wavelet Transform --- p.54 / Chapter 3.4.4 --- Shape Control Parameters --- p.55 / Chapter 3.5 --- Experiments and Discussion --- p.57 / Chapter 3.6 --- Chapter Summary --- p.61 / Chapter 4 --- Matrix-valued Interpolatory Wavelets --- p.63 / Chapter 4.1 --- Introduction --- p.63 / Chapter 4.2 --- Matrix-valued Interpolatory Subdivision --- p.64 / Chapter 4.3 --- Matrix-valued 1-ring Wavelets --- p.67 / Chapter 4.3.1 --- Biorthogonal Wavelet Transform --- p.67 / Chapter 4.3.2 --- Extraordinary Points Treatment --- p.74 / Chapter 4.3.3 --- Shape Control Parameters --- p.75 / Chapter 4.4 --- Matrix-valued 2-ring Wavelets --- p.81 / Chapter 4.5 --- Experiments and Discussion --- p.86 / Chapter 4.5.1 --- 1-ring Wavelet Transform --- p.86 / Chapter 4.5.2 --- 2-ring Wavelet Transform --- p.92 / Chapter 4.6 --- Chapter Summary --- p.98 / Chapter 5 --- Geometry compression using wavelets. --- p.100 / Chapter 5.1 --- Introduction --- p.100 / Chapter 5.2 --- Related Work --- p.101 / Chapter 5.3 --- Matrix-valued Wavelet Transform --- p.105 / Chapter 5.3.1 --- Matrix-valued Loop Subdivision --- p.105 / Chapter 5.3.2 --- Lazy Wavelet --- p.108 / Chapter 5.3.3 --- Inner Product --- p.109 / Chapter 5.3.4 --- Wavelet Transform --- p.112 / Chapter 5.3.5 --- Coding --- p.113 / Chapter 5.4 --- Experiments and discussion --- p.114 / Chapter 5.4.1 --- Stability --- p.117 / Chapter 5.4.2 --- Efficiency --- p.118 / Chapter 5.4.3 --- Compressions --- p.120 / Chapter 5.5 --- Chapter Summary --- p.124 / Chapter 6 --- Conclusions --- p.125 / Chapter 6.1 --- Research Summary --- p.125 / Chapter 6.2 --- Future Work --- p.127 / Chapter A --- Inner Products of Wavelets in Radial Layers --- p.130 / Chapter B --- Publication List --- p.133 / Bibliography --- p.134

La modélisation de vagues et de leur impact côtier et offshore (déferlement, interactions avec les structures, tsunami) reste un problème difficile à appréhender du fait de la complexité des phénomènes physiques mis en jeu. Dans cette thématique, une étude numérique des processus physiques est effectuée dans le cadre de cette thèse. L’objectif de la thèse est ainsi d’améliorer le domaine de validité du code en y développant des méthodes numériques performantes qui permettraient une grande précision des résultats des simulations et des gains en temps de calcul. Le modèle numérique utilisé repose sur les équations d'Euler 3D multi-fluides. Une méthode de compressibilité artificielle permet une approche explicite et une parallélisation efficace. Le modèle bi-fluide à faible Mach, déjà validé avec des données expérimentales, repose sur une approximation par volumes finis avec un schéma de Godunov du second ordre en temps et en espace. Dans le cadre de nos travaux, une modification de la technique d’intégration en temps du solveur basée sur l’intégration d’Adams-Bashforth multi-pas avec une approche multi-échelle dans laquelle le pas de temps est ajusté à la taille locale du maillage et une méthode de compression d’interface pour une meilleure précision de l’interface entre les fluides sont implémentées dans le code. Ces méthodes numériques ont été validées avec des mesures expérimentales dans le cas d’un déferlement 2D et de la rupture 3D de barrage avec obstacle. Des comparaisons expérimentales et numériques ont permis de constater la pertinence des développements apportés au logiciel avec une amélioration de la précision des résultats et une diminution des temps de calcul. / The aim of the thesis is thus to improve the field validity for the CFD(Computational Fluid Dynamics) code for waves modelling, by integrating new numerical methods more efficient. The project should eventually lead to make a powerful simulation tool that can be used for forecasting the impact of waves in coastal areas and offshore. It is therefore completely in line with PRINCIPIA development activities in hydrodynamic with the aim of strengthening its position and support its growth. In this paper, we first focus on the specific problem of numerical diffusion for the convection equation that models the two fluid interface discontinuities. Interface compression methods allowing limiting the interface diffusion problem are presented. The main advantages of these compression methods are that they keep properly the interface and minimize the spurious free surface diffusion which may be beneficial in case of strongly nonlinear motion of the free surface. Moreover, they are easy to implement for problems in two or three dimensions. In the other hand, an improvement of the solver is presented; it concerns the development and validation of the Adams-Bashforth multi-scale time integration method which adjusts the time step depending on the local size cell. The advantage of this method is that it significantly reduces the computation time when small cells are mixed with large cells in the mesh domain. Each cell is assigned with a level of CFL only based on a geometric criterion. The improved model is validated. It is confronted with experimental results of 2D solitary wave breaking on a sloping bottom and the 3D dam break problem over a rectangular obstacle. In both cases, a very satisfactory agreement is found, with a better interface definition with the sharpening method and a significant gain in CPU time with Adams-Bashforth multi-scale time integration method.

重覆數據删除技術是一個消除冗餘數據存儲塊的技術。尤其是，在儲存數兆位元組的虛擬機器影像時，它已被證明可以減少使用磁碟空間。但是，在會經常加入和讀取虛擬機器影像的雲端平台，部署重覆數據删除技術仍然存在挑戰。我們提出了一個在內核運行的重覆數據删除檔案系統LiveDFS，它可以在一個在低成本硬件配置的開源雲端平台中作為儲存虛擬機器影像的後端。LiveDFS有幾個新穎的特點。具體來說，LiveDFS中最重要的特點是在考慮檔案系統佈局時，它利用空間局部性放置重覆數據删除中繼資料。LiveDFS是POSIX兼容的Linux內核檔案系統。我們透過使用42個不同Linux發行版的虛擬機器影像，在實驗平台測試了LiveDFS的讀取和寫入性能。我們的工作證明了在低成本硬件配置的雲端平台部署LiveDFS的可行性。 / Deduplication is a technique that eliminates the storage of redundant data blocks. In particular, it has been shown to effectively reduce the disk space for storing multi-gigabyte virtual machine (VM) images. However, there remain challenging deployment issues of enabling deduplication in a cloud platform, where VM images are regularly inserted and retrieved. We propose a kernel-space deduplication file systems called LiveDFS, which can serve as a VM image storage backend in an open-source cloud platform that is built on low-cost commodity hardware configurations. LiveDFS is built on several novel design features. Specifically, the main feature of LiveDFS is to exploit spatial locality of placing deduplication metadata on disk with respect to the underlying file system layout. LiveDFS is POSIX-compliant and is implemented as Linux kernel-space file systems. We conduct testbed experiments of the read/write performance of LiveDFS using a dataset of 42 VM images of different Linux distributions. Our work justifies the feasibility of deploying LiveDFS in a cloud platform under commodity settings. / Detailed summary in vernacular field only. / Ng, Chun Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 39-42). / Abstracts also in Chinese. / Chapter 1 --- Introduction --- p.1 / Chapter 2 --- LiveDFS Design --- p.5 / Chapter 2.1 --- File System Layout --- p.5 / Chapter 2.2 --- Deduplication Primitives --- p.6 / Chapter 2.3 --- Deduplication Process --- p.8 / Chapter 2.3.1 --- Fingerprint Store --- p.9 / Chapter 2.3.2 --- Fingerprint Filter --- p.11 / Chapter 2.4 --- Prefetching of Fingerprint Stores --- p.14 / Chapter 2.5 --- Journaling --- p.15 / Chapter 2.6 --- Ext4 File System --- p.17 / Chapter 3 --- Implementation Details --- p.18 / Chapter 3.1 --- Choice of Hash Function --- p.18 / Chapter 3.2 --- OpenStack Deployment --- p.19 / Chapter 4 --- Experiments --- p.21 / Chapter 4.1 --- I/O Throughput --- p.21 / Chapter 4.2 --- OpenStack Deployment --- p.26 / Chapter 5 --- Related Work --- p.34 / Chapter 6 --- Conclusions and Future Work --- p.37 / Bibliography --- p.39

從文件系統設計的角度,我們探索了利用重復數據删除技術來消除硬盤陣列存儲設備當中的重復數據。我們提出了ScaleDFS,一個重復數據删除技術的文件系統, 旨在硬盤陣列存儲設備上實現可擴展的吞吐性能。ScaleDFS有三個主要的特點。第一,利用多核CPU並行計算出用作識別重復數據的加密指紋,以提高寫入速度。第二,緩存曾經讀取過的重復數據塊,以顯著提高讀取速度。第三,優化用作查找指紋的內存數據結構,以更加節省內存。ScaleDFS是一個以Linux系統內核模塊開發的,與POSIX兼容的,可以用在一般低成本硬件配置上的文件系統。我們進行了一系列的微觀性能測試,以及用42個不同版本的Linux虛擬鏡像文件進行了宏觀性能測試。我們證實,ScaleDFS在磁盤陣列上比目前已有的開源重復數據删除文件系統擁有更好的讀寫性能。 / We explore the use of deduplication for eliminating the storage of redundant data in RAID from a file-system design perspective. We propose ScaleDFS, a deduplication file system that seeks to achieve scalable read/write throughput in RAID. ScaleDFS is built on three novel design features. First, we improve the write throughput by exploiting multiple CPU cores to parallelize the processing of the cryptographic fingerprints that are used to identify redundant data. Second, we improve the read throughput by specifically caching in memory the recently read blocks that have been deduplicated. Third, we reduce the memory usage by enhancing the data structures that are used for fingerprint lookups. ScaleDFS is implemented as a POSIX-compliant, kernel-space driver module that can be deployed in commodity hardware configurations. We conduct microbenchmark experiments using synthetic workloads, and macrobenchmark experiments using a dataset of 42 VM images of different Linux distributions. We show that ScaleDFS achieves higher read/write throughput than existing open-source deduplication file systems in RAID. / Detailed summary in vernacular field only. / Ma, Mingcao. / "October 2012." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 39-42). / Abstracts also in Chinese. / Chapter 1 --- Introduction --- p.2 / Chapter 2 --- Literature Review --- p.5 / Chapter 2.1 --- Backup systems --- p.5 / Chapter 2.2 --- Use of special hardware --- p.6 / Chapter 2.3 --- Scalable storage --- p.6 / Chapter 2.4 --- Inline DFSs --- p.6 / Chapter 2.5 --- VM image storage with deduplication --- p.7 / Chapter 3 --- ScaleDFS Background --- p.8 / Chapter 3.1 --- Spatial Locality of Fingerprint Placement --- p.9 / Chapter 3.2 --- Prefetching of Fingerprint Stores --- p.12 / Chapter 3.3 --- Journaling --- p.13 / Chapter 4 --- ScaleDFS Design --- p.15 / Chapter 4.1 --- Parallelizing Deduplication --- p.15 / Chapter 4.2 --- Caching Read Blocks --- p.17 / Chapter 4.3 --- Reducing Memory Usage --- p.17 / Chapter 5 --- Implementation --- p.20 / Chapter 5.1 --- Choice of Hash Function --- p.20 / Chapter 5.2 --- OpenStack Deployment --- p.21 / Chapter 6 --- Experiments --- p.23 / Chapter 6.1 --- Microbenchmarks --- p.23 / Chapter 6.2 --- OpenStack Deployment --- p.28 / Chapter 6.3 --- VM Image Operations in a RAID Setup --- p.33 / Chapter 7 --- Conclusions and FutureWork --- p.38 / Bibliography --- p.39

Based on the fixed block size FWS algorithm, we further proposed a fast full-pel variable block size motion estimation algorithm called Fast Walsh Search in Variable Block Size (FWS-VBS). As in FWS, FWS-VBS employs the PSAD as the error measure to identify likely mismatches. Mismatches are rejected by thresholding method and the thresholds are determined adaptively to cater for different activity levels in each block. Early termination techniques are employed to further reduce the number of candidates and modes to be searched of each block. FWS-VBS performs equally well to the exhaustive full search algorithm in the reference H.264/AVC encoder and requires only about 10% of the computation time. / Furthermore, we modified our proposed segmentation algorithm to handle video sequences that are already encoded in the H.264 format. Since the video is compressed, no spatial information is available. Instead, quantized transform coefficients of the residual frame are used to approximate spatial information and improve segmentation result. The computation time of the segmentation process is merely about 16ms per frame for CIF frame size video, allowing the algorithm to be applied in real-time applications such as video surveillance and conferencing. / In the first part of our research, we proposed a block matching algorithm called Fast Walsh Search (FWS) for video motion estimation. FWS employs two new error measures defined in Walsh Hadamard domain, which are partial sum-of-absolute difference (PSAD) and sum-of-absolute difference of DC coefficients (SADDCC). The algorithm first rejects most mismatched candidates using PSAD which is a coarse measure requiring little computation. Because of the energy packing ability of Walsh Hadamard transform (WHT) and the utilization of fast WHT computation algorithm, mismatched candidates are identified and rejected efficiently. Then the proposed algorithm identifies the matched candidate from the remaining candidates using SADDCC which is a more accurate measure and can reuse computation performed for PSAD. Experimental results show that FWS can give good visual quality to most of video scene with a reasonable amount of computation. / In the second part of our research, we developed a real-time video object segmentation algorithm. The motion information is obtained by FWS-VBS to minimize the computation time while maintaining an adequate accuracy. The algorithm makes use of the motion information to identify background motion model and moving objects. In order to preserve spatial and temporal continuity of objects, Markov random field (MRF) is used to model the foreground field. The block-based foreground object mask is obtained by minimizing the energy function of the MRF. The resulting object mask is then post-processed to generate a smooth object mask. Experimental results show that the proposed algorithm can effectively extract moving objects from different kind of sequences, at a speed of less than 100ms per frame for CIF frame size video. / Motion estimation is an important part in many video processing applications, such as video compression, object segmentation, and scene analysis. In all video compression applications, motion information is used to reduce temporal redundancy between frames, thus significantly reduce the required bitrate for transmission and storage of compressed video. In addition, in object-based video coding, video object can be automatically identified by its motion against the background. / Mak, Chun Man. / "June 2008." / Adviser: Wai-Kuen Cham. / Source: Dissertation Abstracts International, Volume: 70-03, Section: B, page: 1849. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.