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30 October 2015, Volume 36 Issue 5 Previous Issue    Next Issue

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Automatic Matching Method for Head Accessory of Virtual Human Zheng Liping, Zhou Chenglong, Cheng Yajun, Chen Xing 2015, 36(5): 655-661.  DOI: 10.11996/JG.j.2095-302X.2015050655 Abstract ( 91 )   PDF (929KB) ( 380 )   The diversity of virtual humanfor simulation is mainly exhibited by the character. The differences between models consist of two parts: the somatotype and the head accessories. Automatic matching head accessories for virtual human will observably increase the realistic of the simulation. A new method for automatic matching is presented. Firstly, we assign simple skeleton to the accessories and choose anchor points after automatic rigging skeleton for virtual models, then execute the matching method to achieve matched model. Finally, we assign various postures to the model by embedskeleton. The result shows our method can match the head attachments to diverse virtual human automatically, and pretty improve the diversification of virtual models. Related Articles | Metrics

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Extraction of Valley-Ridge Lines from Point-Sampled Geometry with Snake Zhang Ruonan, Wang Renfang 2015, 36(5): 662-670.  DOI: 10.11996/JG.j.2095-302X.2015050662 Abstract ( 148 )   PDF (4763KB) ( 452 )   Based on the active contour model, a robust algorithm is proposed for extracting and optimizing valley-ridge lines from point-sampled geometry (PSG). First, local implicit surface of the PSG is reconstructed, and the curvature of every sampling point is computed. Potential valley-ridge points are then obtained by solving the extreme of the main curvature, and potential valley-ridge points is connected into valley-ridge polylines according to the main direction of the feature points. Finally, snake model is used to smooth the valley-ridge polyline. Experimental results show that the algorithm is robust and can generate smooth valley-ridge lines. Related Articles | Metrics

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Research on Intersections of Cone and Cylinder Hu Zhigang, Zheng Qiubai 2015, 36(5): 671-677.  DOI: 10.11996/JG.j.2095-302X.2015050671 Abstract ( 105 )   PDF (812KB) ( 236 )   This paper aims is to discuss the intersections determination of two plane tangent convolutes, a cylinder and a cone, and to analyze different intersection results under different parameters entry, so as to deliver a kind of effective mathematical basis for CAD intersection construction. For a cylinder and a cone, the existence-judgment equation of intersection lines is given. It is also analyzed that intersection existence conditions, numbers and shape properties in both parametric formulas and geometry at special spatial positions, while the method discussion was made of getting exact tangent point of two surfaces at normal spatial position. The structural diagram is delivered of parametric drawing program of multiview, some processing methods coping with several key problems of drawing intersection curve are listed, too. Different intersection lines resulting in connection with corresponding parameters entry are analyzed. The implementation has the functions of multiview drawing, dimensioning and writing main parameters and coordinate data to a data file for intersection lines. Related Articles | Metrics

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A Study of Cellular Derived Law in Architectural Design Zhang Siqi, Shang Tao 2015, 36(5): 678-684.  DOI: 10.11996/JG.j.2095-302X.2015050678 Abstract ( 92 )   PDF (1197KB) ( 196 )   Computer-aided design tools which are available currently have been providing effective support for the later stages of the architectural design process. For the initial stage of architectural design, in which design concept is mature whereasthe structure and shape are not determined, a new kind of solution should be needed to support designers way of thinking and inspire the creation of design. Thus, in this paper, a new method of architectural generation based on shape grammar is proposed to describe the animation of the complex 3D forms. It tells how to create an initial shape by limited rules, then automatically generate genetic shapes, and finally grow into a complex system by modifying the adaptable rule. Also, the developed shape grammar framework allows designers to actively participate in the generation process. Finally, the modeling of CFS wall prototype is taken as an example to verify the effectiveness and practicality of this method. Related Articles | Metrics

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Finite Element Analysis and Optimal Design of Invisible Braces Yue Yanfang, Wang Yang, Zhang Yongdi, Yang Guang, Wang Qiaoling 2015, 36(5): 686-690.  DOI: 10.11996/JG.j.2095-302X.2015050686 Abstract ( 128 )   PDF (968KB) ( 299 )   隐形矫治器；变厚度模型；有限元分析；优化设计 Related Articles | Metrics

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Computational Methods of Invariants of Coplanar Polygons Zhang Zhengwu 2015, 36(5): 691-696.  DOI: 10.11996/JG.j.2095-302X.2015050691 Abstract ( 108 )   PDF (725KB) ( 203 )   The comprehensive and recognition of 3D scene based on invariants are the most important research areas in computer vision fields. The conventional studies of invariants are that these invariants are derived for planar objects using points, lines, and conics from images. The invariants of triangular, quadrilateral, pentagonal and hexagon are structured by use of triangular area from 2D points perspective projection in this paper. And the computational methods of the invariants are derived. The result of example shows that this formula is correct on the basis of studies. Related Articles | Metrics

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A Localization Algorithm for Plate Surface in Line Heating Pan Weijie, Cheng Lianglun, Wang Tao, Liu Li 2015, 36(5): 697-702.  DOI: 10.11996/JG.j.2095-302X.2015050697 Abstract ( 107 )   PDF (644KB) ( 188 )   In the process of shipbuilding automation, it needs to arrange flame lines for line heating. When arranging flame lines, it needs to locate flame lines on plate surface. Therefore, a localization algorithm suitable for plate surface is proposed in this paper, allowing locating and arranging planed flame lines on plate surface when location information of flame lines end points is given; and it could figure out location information of settled flame lines vice versa. Related Articles | Metrics

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A Method of Product Appearance Design Based on Graphical Semantic Cognition Lv Jian, Xie Qingsheng, Huang Haisong, Pan Weijie 2015, 36(5): 703-711.  DOI: 10.11996/JG.j.2095-302X.2015050703 Abstract ( 127 )   PDF (1357KB) ( 366 )   In the process of product design knowledge representation, a product design process knowledge model based on graphical semantic cognition is presented. Through the ontology semantic analysis and the design information processing mode analysis of human brain in the process of product design, extension origin and extension vector were presented to achieve knowledge representation in the design process which contains growth, convergence and optimization. On the basis of the characterization methods above, this paper studies characterization methods and clustering mode of case library. This paper takes a machine tool appearance design as an example, and this method has a good effect in the design process which can be a method reference for industrial design. Related Articles | Metrics

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Mechanical Conceptual Design Oriented Knowledge Database Organized by Domain Ontology Guo Qiantong, Tian Ling 2015, 36(5): 712-723.  DOI: 10.11996/JG.j.2095-302X.2015050712 Abstract ( 133 )   PDF (1786KB) ( 260 )   Since the current mechanical conceptual design oriented knowledge databases lacked of accurate definition of the function and efficient reusing of implicit knowledge, a conceptual design oriented knowledge database based on domain ontology was built, which could provide data operating functions such as self-service application and semantic retrieval. The logical structure and modeling of design knowledge were proposed to build the domain ontology. Multi-dimensional classification schemes of design knowledge were set up considering different granularities and functions of design projects and knowledge managements. The issuing, maintaining, storage and retrieval of design knowledge were realized by conversions of extensible markup languages. With the powerful knowledge management system, designers could reuse and share implicit knowledge efficiently in design activities, which facilitated the innovation of mechanical conceptual design. Related Articles | Metrics

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Soybean Impacting Simulation Analysis in Threshing Process Based on SolidWorks Simulation and Orthogonal Test Dun Guoqiang, Chen Haitao, Liu Huanyu, Feng Yining, Zha Shaohui, Hou Shouyin 2015, 36(5): 724-729.  DOI: 10.11996/JG.j.2095-302X.2015050724 Abstract ( 129 )   PDF (1427KB) ( 246 )   In order to explore the response about the impact of impacting parameters changing on soybean seed stress distribution and deforming displacement, the simulation analysis of the impacting processing between soybean and contacting plane has been done by using SolidWorks Simulation and obtained soybean models stress distribution and deforming displacement with times changing in soybean impacting processing, the impacting velocity and contact radius were selected as factors and the model stress maximum and the displacement maximum were selected as indexes, using orthogonal testing method to analyze factors affecting indexes. The test results indicate that two factors have significant influence on the model stress maximum, for index displacement, contact radius was significant, impact velocity was notable. Meanwhile, two indexes increased with impact velocitys increasing, but when contact radius increased, the indexes first decreased and then decreasing trend become slowing. At last, the results of the research provided a reference for soybean seed threshers simulation design and product research and development. Related Articles | Metrics

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Application of Associated Design Technology on Wing Components Rapid Modeling Chen Dongming, Xi Ping, Tang Jiapeng 2015, 36(5): 730-733.  DOI: 10.11996/JG.j.2095-302X.2015050730 Abstract ( 120 )   PDF (691KB) ( 207 )   Aircraft and other complex product design process is becoming a full three-dimensional process. It is quite important to create and maintain model accurately and quickly, which significantly affect the product design cycle. Parts rapid modeling can effectively improve the efficiency of three-dimensional model creating, while it is limited to create a single part quickly. Associated design makes a rapid component modeling possible. Focused on these questions, this paper studies the combination of associated design and rapid modeling, presents a detailed method combining associated design techniques with wing components rapid modeling and verifies the effectiveness of the model through a rapid modeling tool based on such technique. Related Articles | Metrics

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A Metamorphosis Method Based on Triangular Decomposition for Product Shape Design Sha Chunfa, Lu Zhangping, Yang Huachun, Guo Jianhong 2015, 36(5): 734-739.  DOI: 10.11996/JG.j.2095-302X.2015050734 Abstract ( 124 )   PDF (808KB) ( 202 )   This paper presented a metamorphosis method based on triangular decomposition for product shape design. Firstly, two given triangular mesh models were projected on to the surface of a unit sphere. Secondly, the edge characteristics were calculated. Then the topological model of new models was got based on the two kinds of triangular decomposition rulers proposed in this paper. So, the spatial relationships of vertexes and shape features between the middle model and two given models could be built. Lastly, the new models were made with linear interpolation. Testes indicated that the proposed approach needed no topological merging and artificial interference and could preserve the visual features of the given models effectively. It was shown that these characters were suitable for industrial designers who had no special knowledge about the metamorphosis technologies to create new shapes for product form design. Related Articles | Metrics

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An Improved Variational Level Set Used in Image Segmentation Algorithm Zhang Guimei, Zhou Feifei, Chu Jun 2015, 36(5): 740-746.  DOI: 10.11996/JG.j.2095-302X.2015050740 Abstract ( 138 )   PDF (1032KB) ( 259 )   To solve the problem caused by intensity inhomogeneity in medical images, this paper proposed an active contour model based on the local polarity information. By incorporating the local information of image, the proposed model can efficiently segment the image which intensity is nonuniform. Through introducing a penalizing energy term into the regularization, the level set function can be approximated as a signed distance function all the time in the process. This algorithm regarded the image segmentation as the task to minimize the curve of energy functional. Firstly, to establish the evolution curve of energy functional including the local gray level information (polarity information) and the improved signed distance function. Then to solve the minimization of energy function by using the variational level set method to be able to get the final segmentation result. The experiment results of real medical images and artificial synthesis images have shown that our method can get a higher precision of segmentation for the medical images with uneven grayscale. In addition, the image processing speed has been improved greatly. Because of the utilization of local gray information, we can segment the medical image with uneven grayscale effectively, the improved variational level set can completely avoid the re-initialization, and greatly improve the efficiency of image segmentation. Related Articles | Metrics

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Video Semantic Context Label Tree and Its Structural Analysis Yu Chunyan, Su Chenhan 2015, 36(5): 747-755.  DOI: 10.11996/JG.j.2095-302X.2015050747 Abstract ( 176 )   PDF (1050KB) ( 418 )   Video content is strongly associated with time series and has a strong logical structure. Shot semantic is a kind of basic unit for understanding video content. From the point view of user cognition, among shot semantics, there are various context information hidden rather than explicit temporal association, such as logical and structural association. Obviously, it is important to describe these context information in an reasonable manner. Firstly, this paper presents a label tree with context label to represent the structured context as characterization model of video semantic context. Within the label tree, each shot semantic in a shot semantic sequence is taken as a leaf node and all inner nodes with context label is adopted to represent the inter-dependencies among its child nodes. More important, its hierarchical structure, corresponding to the hierarchical model of video content, leads to significant information gain for video content understanding. Furthermore, it is tough to construct a hierarchical video semantic context label tree from the shot semantic sequence, which needs to bridge from sequence space to tree structure space. Then, according to the combined feature of shot semantic sequence and video semantic label tree, this paper uses an SVM-Struct analysis to construct structural function and loss function for the semantic context and implement the construction of video semantic context label tree. The experimental results show that video semantic context label tree has a better characterization ability in many aspects. And SVM-Struct driven analysis ensures the characterization ability of video semantic label tree with high precision, recall and F1 rate. Related Articles | Metrics

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Combining Region-Based Model with Geodesic Active Contour for Nature Image Segmentation Using Graph Cut Optimization Song Lin, Gao Mantun, Wang Sanmin, Wang Shuxia 2015, 36(5): 756-762.  DOI: 10.11996/JG.j.2095-302X.2015050756 Abstract ( 83 )   PDF (1488KB) ( 285 )   As the active contour model segments images using level set formulation, such formulation results in very slow algorithms that get easily stuck in local solutions and only segment image with intensity homogeneity. In this paper, a new model combining region-based with geodesic active contours is proposed for image segmentation. The new energy functional can be iteratively minimized by graph cut algorithms with high computational efficiency compared with the level set framework. Experiment results show that the proposed model can effectively and efficiently segment images with intensity inhomogeneity. The method is less sensitive to the location of initial contour and can also avoid local minima solutions. Related Articles | Metrics

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Image Threshold Selection Based on Two-Dimensional Asymmetric Tsallis Cross Entropy and Decomposition Wu Shihua, Wu Yiquan, Zhou Jianjiang 2015, 36(5): 763-770.  DOI: 10.11996/JG.j.2095-302X.2015050763 Abstract ( 109 )   PDF (883KB) ( 229 )   The existing Tsallis cross entropy can measure the difference between the original image and its segmentation result, but it has the drawback of complex formula and low computational efficiency. Thus two-dimensional asymmetric Tsallis cross entropy threshold selection method based on decomposition is proposed. Firstly, the asymmetric Tsallis cross entropy is defined and a one-dimensional threshold selection method based on the asymmetric Tsallis cross entropy is put forward. Then it is extended to the two-dimensional space, and the corresponding threshold selection formulae are derived. Finally, the decomposition algorithm of two-dimensional asymmetric Tsallis cross entropy thresholding is proposed on this basis. As a result, the computations of two-dimensional asymmetric Tsallis cross entropy thresholding method are converted into two one-dimensional spaces. The computational complexity is greatly reduced from O(L4) to O(L). A large number of experimental results show that, compared with two-dimensional maximum Tsallis gray entropy method based on chaos particle swarm optimization, symmetric cross entropy method based on two-dimensional histogram oblique segmentation, symmetric Tsallis cross entropy method based on two-dimensional histogram oblique segmentation and so on, the proposed method has superior image segmentation performance and short running time, which can meet the real-time processing requirement of segmentation in the practical application systems. Related Articles | Metrics

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A Measurement Method for Soft Tissue Deformation Based on Image Morphology Bai Huiquan, Gao Dedong, Wang Shan, Li Qiang, Zheng Haojun 2015, 36(5): 771-775.  DOI: 10.11996/JG.j.2095-302X.2015050771 Abstract ( 116 )   PDF (847KB) ( 209 )   A method is provided for measuring soft tissue deformation based on the image morphology in order to obtain the amount of tissue deformation during needle insertion procedure accurately. The algorithms of edge detection, image expansion and corrosion are explained and employed to enhance the images of the markers embedded into soft tissue. The centroids of the markers are extracted and stored into the measurement matrix M. A measurement platform, including the precision motion stage, industrial camera, light source and crystal artificial tissue with marker, is built. The real-time images are collected during needle insertion procedure. The displacements of the markers are calculated using the morphology-based method. The measurement error is less than 0.7 mm with the compensation. The method could improve the accuracy and precision of robot-assisted needle insertion surgeries. Related Articles | Metrics

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Window Detection Based on Constraints of Image Edges and Glass Attributes Miao Jun, Chu Jun, Zhang Guimei 2015, 36(5): 776-782.  DOI: 10.11996/JG.j.2095-302X.2015050776 Abstract ( 137 )   PDF (2124KB) ( 371 )   Window detection is one of the important researches on building image understanding. We proposed an approach of window detection under edges and glass attribute constraints. Firstly, windows are basically located with edges in image. Next, color and texture features on the edge neighbor are extracted, and the dissimilarities between the two features are applied for windows recognition. Finally, the Mahalanobis distance classifier is first adopted to improve the local recognition containing window area, then the image segmentation algorithm is used to extract the whole area of the window. Experiments show that our proposed approach can efficiently detect windows in the case of unknowing the shape and structure of windows. Related Articles | Metrics

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An Edge Extraction Method for Polluted Text Image of Ancient Inscription Wall Liu Yingjie, Yang Fengbao, Ji Linna, Yuan Huifeng 2015, 36(5): 783-788.  DOI: 10.11996/JG.j.2095-302X.2015050783 Abstract ( 111 )   PDF (696KB) ( 211 )   On the issue that inscription text image of the ancient wall is contaminated leading to its edge extraction is not complete, easy to produce false edge and discontinuous margin, this paper proposes a novel method of edge extraction from polluted inscription text. Firstly, text image for total variation denoising and multi-scale retinal algorithm shading to enhance preprocessing is used. Then construct a shadow-blocking quasi-invariant model filtering out pollution and pseudo-edge generated by background. Meanwhile, use Gabor filter to do spatial averaging and establish color structure tensor combined with Canny algorithm to do edge detection. Finally, filter small area edge existing in the image by morphological method and do the regional connectivity to obtain the edge inscription text image. The results show that, compared to traditional Canny algorithm and morphological method, this method effectively overcomes the false edge and discontinuous edge caused by dirt and background which makes good extraction of edge inscription from the full text and a more objective indicators such that edge quality has improved significantly. Related Articles | Metrics

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Realization of Basketball Training Simulation System Zhang Dianhua, Chen Yimin 2015, 36(5): 789-794.  DOI: 10.11996/JG.j.2095-302X.2015050789 Abstract ( 122 )   PDF (681KB) ( 261 )   In view of the lack of quantitative calculation problems in the current basketball training, the basketball training simulation system was developed. The exact solution of the best shot angle and velocity of shots without air resistance is solved using the trajectory equation of basketball movement whose start and end point are not in the same level. The result shows that the best shot angle will increase with the increasement of the shot speed, decrease with the increasement of the shot height. With the increasement of the shot distance, the minimum shot speed need to be increased, and the best shot angle is decreased. At the same time, a visual simulation environment is created which includes the animation of athletes, the basketballs with physical material, sound, level design, the best shot angle calculation module and network scoring module. Players can use the visual environment to measure the best shot angle and shot speed for auxiliary training. Related Articles | Metrics

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Methods for Rapidly Planning Task Simulation and Automatically Generating Simulating Steps According to Division of Task Semantics Wu Zhenfa, Zhao Huangjin, Zheng Guolei 2015, 36(5): 795-801.  DOI: 10.11996/JG.j.2095-302X.2015050795 Abstract ( 140 )   PDF (839KB) ( 223 )   Generally, the simulation of a human task with a computer-aided ergonomic system is always required in all the modern engineering activities, and it is one of most specialized and complicated works. So it is of importance to research and set up the procedure for rapidly planning a task simulation. But a great deal of interactions is needed during the application of current ergonomic systems so far, and the simulation steps cannot be created automatically. This paper proposes methods for rapidly planning the task simulation and automatically generating the simulating steps according to the division of the task semantics. Firstly, with the structure of hierarchical scheme, the natural semantics of an ergonomic task are divided into layers, in which all the leaf nodes are defined as the actions which can be performed or implemented with an ergonomic system at present. Secondly, the new concepts of task path, task trace and task process are defined, and the complex task is structurally modeled with the application of a proposed graphic scheme. The procedure of automatic generation of a task simulation steps is constructed. Finally, the program is developed, which is required to support the implementation of the established methods for planning the task simulation and automatically producing the simulation data. Taking the opening of a board of fixture during the aircraft assembly, these proposed methods are tested and verified. Related Articles | Metrics

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A Review for Researches and Applications of BIM-Based Operation and Maintenance Management Hu Zhenzhong, Peng Yang, Tian Peilong 2015, 36(5): 802-810.  DOI: 10.11996/JG.j.2095-302X.2015050802 Abstract ( 499 )   PDF (562KB) ( 1543 )   Introducing BIM into building operation and maintenance management (O&M management) has significant benefits. Though the number of related literatures keeps increasing in recent years, current domestic and foreign researches and applications on BIM-based O&M are generally in the exploratory stage. Based on a broad literature survey, this paper reviewed domestic and foreign BIM-based O&M researches and applications from the perspective of technology researches and application projects. Relevant key technologies, research status and related system developments were introduced. The functions and project applications were then summarized. Finally the challenges and bottlenecks for BIM-based O&M management, as well as an outlook for future researches were discussed. Related Articles | Metrics

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Investigation to Efficiently Edit Displaying Effects of Figures with AutoCAD Data Format Embedded in Word Documents Jing Tianhu, Ma Xiaolong, Liu Junli, Mo Shixu 2015, 36(5): 811-818.  DOI: 10.11996/JG.j.2095-302X.2015050811 Abstract ( 120 )   PDF (1727KB) ( 239 )   Basing on analysis of the existing methods to making figures and displaying principle for drawings of AutoCAD software, uncontrolled phenomena of displaying effects of figures with AutoCAD data format embedded in word documents are investigated by means of trial and error. The study indicates that dimensions of drawing window and state information of view in AutoCAD software are important factors to determine displaying effects of figures in documents during editing them. These measurements, such as using the methods which can save entire view information to produce illustrations, editing drawings under maximum displaying state of working interface of AutoCAD software, restoring preliminary view state in time, keeping unchanged the environments of software and hardware when editing drawing every time, et al. can make displaying effects of figures always controllable, thereby to obviously improve editing efficiency when editing illustrations in documents. Related Articles | Metrics