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Decomposition Method of Complex Optimization Model Based on Global Sensitivity Analysis

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Chinese Journal of Mechanical Engineering 2014年第4期27卷 722-729页

作者： QIU Qingying LI Bing FENG Peien GAO Yu State key laboratory of cad&cg Zhejiang University

The current research of the decomposition methods of complex optimization model is mostly based on the principle of disciplines, problems or components. However, numerous coupling variables will appear among the sub-models decomposed, thereby make the efficiency of decomposed optimization low and the effect poor. Though some collaborative optimization methods are proposed to process the coupling variables, there lacks the original strategy planning to reduce the coupling degree among the decomposed sub-models when we start decomposing a complex optimization model. Therefore, this paper proposes a decomposition method based on the global sensitivity information. In this method, the complex optimization model is decomposed based on the principle of minimizing the sensitivity sum between the design functions and design variables among different sub-models. The design functions and design variables, which are sensitive to each other, will be assigned to the same sub-models as much as possible to reduce the impacts to other sub-models caused by the changing of coupling variables in one sub-model. Two different collaborative optimization models of a gear reducer are built up separately in the multidisciplinary design optimization software iSIGHT, the optimized results turned out that the decomposition method proposed in this paper has less analysis times and increases the computational efficiency by 29.6%. This new decomposition method is also successfully applied in the complex optimization problem of hydraulic excavator working devices, which shows the proposed research can reduce the mutual coupling degree between sub-models. This research proposes a decomposition method based on the global sensitivity information, which makes the linkages least among sub-models after decomposition, and provides reference for decomposing complex optimization models and has practical engineering significance.

关键词： multidisciplinary design optimization collaborative optimization sensitivity analysis coupled factorization iSIGHT

Real-time camera tracking using hybrid features in mobile augmented reality

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Science China(Information Sciences) 2015年第11期58卷 211-223页

作者： WANG WeiJie WAN HuaGen State key laboratory of cad&cg Zhejiang University

Often only simple features are employed in mobile augmented reality(AR) due to the limited computational capacity of mobile terminals, which often leads to unsteadiness of the camera tracking. In this paper, we propose a novel approach to real-time camera tracking in mobile AR using hybrid features to alleviate this problem. By integrating feature points and lines as scene features, hybrid features are generated through the process of point/line features extraction, optimization and fusion, and are used in the real-time estimation of camera parameters. A method for image feature optimization is proposed based on the scene structural analysis to meet the computational constraints of mobile terminals. In order to improve the stability of camera tracking, an iterative screening method is proposed to choose a set of stable feature lines, and hybrid features are adaptively constructed based on the composition and geometry of scene features. It is shown from the experimental results that the proposed method produces more stable and smoother camera trajectories in comparison with the method only using feature points, and a good balance is achieved between the stability and the real-time computation of the camera tracking on a mobile platform.

关键词： mobile augmented reality feature extraction camera tracking hybrid feature mobile platform

Quantitative information measurement and application for machine component classification codes

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2005年第B8期6卷 35-40页

作者：李凌丰谭建荣刘波 State key laboratory of cad&cg Zhejiang University

Information embodied in machine component classification codes has internal relation with the probability distribu- tion of the code symbol. This paper presents a model considering codes as information source based on Shannon’s information theory. Using information entropy, it preserves the mathematical form and quantitatively measures the information amount of a symbol and a bit in the machine component classification coding system. It also gets the maximum value of information amount and the corresponding coding scheme when the category of symbols is fixed. Samples are given to show how to evaluate the information amount of component codes and how to optimize a coding system.

关键词： Component classification codes Information source Information amount Information entropy of code bit

Window Detection in Facades Using Heatmap Fusion

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Journal of Computer Science & Technology 2020年第4期35卷 900-912页

作者： Chuan-Kang Li Hong-Xin Zhang Jia-Xin Liu Yuan-Qing Zhang Shan-Chen Zou Yu-Tong Fang State key laboratory of cad&cg Zhejiang UniversityHangzhou 310058China

Window detection is a key component in many graphics and vision applications related to 3D city modeling and scene *** present a novel approach for learning to recognize windows in a colored facade *** than predicting bounding boxes or performing facade segmentation,our system locates keypoints of windows,and learns keypoint relationships to group them together into windows.A further module provides extra recognizable information at the window *** and relationships of keypoints are encoded in different types of heatmaps,which are learned in an end-to-end *** have also constructed a facade dataset with 3418 annotated images to facilitate research in this *** has richly varying facade structures,occlusion,lighting conditions,and angle of *** our dataset,our method achieves precision of 91.4%and recall of 91.0%under 50%IoU(intersection over union).We also make a quantitative comparison with state-of-the-art methods to verify the utility of our proposed *** based on our window detector are also demonstrated,such as window blending.

关键词： facade parsing window detection keypoint localization

Design Theory and Method of Complex Products:A Review

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Chinese Journal of Mechanical Engineering 2022年第5期35卷 1-16页

作者： Chan Qiu Jianrong Tan Zhenyu Liu Haoyang Mao Weifei Hu State key laboratory of cad&cg Zhejiang UniversityHangzhou 310027China

Design is a high-level and complex thinking activity of human beings,using existing knowledge and technology to solve problems and create new *** the rise and development of intelligent manufacturing,design has increasingly reflected its importance in the product life ***,the concept and connotation of complex product design is expounded systematically,and the different types of design are *** four schools of design theory are introduced,including universal design,axiomatic design,TRIZ and general *** the research status of complex product design is analyzed,such as innovative design,digital design,modular design,reliability optimization design,***,three key scientific issues worthy of research in the future are indicated,and five research trends of“newer,better,smarter,faster,and greener”are summarized,aiming to provide references for the equipment design and manufacturing industry.

关键词： Product design Design theory and method Innovative design Digital design

CNLPA-MVS:Coarse-Hypotheses Guided Non-Local PAtchMatch Multi-View Stereo

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Journal of Computer Science & Technology 2021年第3期36卷 572-587页

作者： Qitong Zhang Shan Luo Lei Wang Jieqing Feng State key laboratory of cad&cg Zhejiang UniversityHangzhou 310058China

In multi-view stereo,unreliable matching in low-textured regions has a negative impact on the completeness of reconstructed *** the photometric consistency of low-textured regions is not discriminative under a local window,non-local information provided by the Markov Random Field(MRF)model can alleviate the matching ambiguity but is limited in continuous space with high computational *** to its sampling and propagation strategy,PatchMatch multi-view stereo methods have advantages in terms of optimizing the continuous labeling *** this paper,we propose a novel method to address this problem,namely the Coarse-Hypotheses Guided Non-Local PAtchMatch Multi-View Stereo(CNLPA-MVS),which takes the advantages of both MRF-based non-local methods and PatchMatch multi-view stereo and compensates for their defects ***,we combine dynamic programing(DP)and sequential propagation along scanlines in parallel to perform CNLPA-MVS,thereby obtaining the optimal depth and normal ***,we introduce coarse inference within a universal window provided by winner-takes-all to eliminate the stripe artifacts caused by DP and improve ***,we add a local consistency strategy based on the hypotheses of similar color pixels sharing approximate values into CNLPA-MVS for further improving ***-MVS was validated on public benchmarks and achieved state-of-the-art performance with high completeness.

关键词： 3D reconstruction multi-view stereo PatchMatch dynamic programming

The Convergence of Least-Squares Progressive Iterative Approximation for Singular Least-Squares Fitting System

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Journal of Systems Science & Complexity 2018年第6期31卷 1618-1632页

作者： LIN Hongwei CAO Qi ZHANG Xiaoting School of Mathematical Science State Key Laboratory of CAD&CG Zhejiang University

Data fitting is an extensively employed modeling tool in geometric design. With the advent of the big data era, the data sets to be fitted are made larger and larger, leading to more and more least-squares fitting systems with singular coefficient matrices. LSPIA (least-squares progressive iterative approximation) is an efficient iterative method for the least-squares fitting. However, the convergence of LSPIA for the singular least-squares fitting systems remains as an open problem. In this paper, the authors showed that LSPIA for the singular least-squares fitting systems is convergent. Moreover, in a special case, LSPIA converges to the Moore-Penrose (M-P) pseudo-inverse solution to the least- squares fitting result of the data set. This property makes LSPIA, an iterative method with clear geometric meanings, robust in geometric modeling applications. In addition, the authors discussed some implementation detail of LSPIA, and presented an example to validate the convergence of LSPIA for the singular least-squares fitting systems.

关键词： Data fitting geometric modeling LSPIA singular least-squares fitting system.

Trivariate B-spline solid construction by pillow operation and geometric iterative fitting

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Science China(Information Sciences) 2018年第11期61卷 232-234页

作者： Hongwei LIN Hao HUANG Chuanfeng HU School of Mathematical Science State Key Laboratory of CAD&CG Zhejiang University

While the traditional geometric design community focuses on the design of curves and surfaces, the advent of isogeometric analysis (IGA)[1] has made the development of methods for designing trivariate B-spline solids (TBSs) imperative. In IGA, a valid TBS should have a positive Jacobian value at every point in its domain. A negative Jacobian value at any point in the domain of the TBS can render the IGA invalid.

关键词： TBS Trivariate B-spline solid construction by pillow operation and geometric iterative fitting GFD Figure

Watermarking on 3D mesh based on spherical wavelet transform

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2004年第3期5卷 2-9页

作者：金剑秋戴敏雅鲍虎军彭群生 State key laboratory of cad&cg AI Institute Zhejiang University

In this paper we propose a robust watermarking algorithm for 3D mesh. The algorithm is based on spherical wavelet transform. Our basic idea is to decompose the original mesh into a series of details at different scales by using spherical wavelet transform; the watermark is then embedded into the different levels of details. The embedding process includes: global sphere parameterization, spherical uniform sampling, spherical wavelet forward transform, embedding watermark, spherical wavelet inverse transform, and at last resampling the mesh watermarked to recover the topological connectivity of the original model. Experiments showed that our algorithm can improve the capacity of the watermark and the robustness of watermarking against attacks.

关键词： Mesh watermarking Spherical wavelet transform Spherical parameterization