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30 June 2011, Volume 32 Issue 3 Previous Issue    Next Issue

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Volume Clipping Technology Based on Multi-resolution Clipping Texture LUO Yue-tong, XUE Ye, LONG Peng-cheng, WU Guo-yong 2011, 32(3): 1-5.  Abstract ( 97 )   PDF (484KB) ( 231 )   A multi-resolution clipping texture with INDEX-DATA structure is presented to solve the huge size problem of single-resolution clipping texture data. Firstly, definition and structure of multi-resolution clipping texture are introduced; then multi-resolution clipping texture’s construction method and volume clipping technology based on multi-resolution clipping texture are discussed; finally, experiment results are discussed. The method presented in the paper has been applied in visualization software SVIP and the result is satisfactory. Related Articles | Metrics

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An Object Localization Algorithm Based on Omni-direction Vision and Front Monocular Vision FANG Bao-fu, PAN Qi-shu, HONG Bing-rong, ZHONG Qiu-bo, WANG Wei-guang 2011, 32(3): 6-12.  Abstract ( 138 )   PDF (603KB) ( 263 )   In the robot soccer system, the environmental information around the robot is characterized in colors. On the analysis of the color threshold segmentation, an improved algorithm practicable in different color environments is proposed to realize the identification of objects in different colors in the field through omni-direction vision and front monocular vision, by the use of which, the robot’s object location through the two visions can be realized and then a more accurate object location can be achieved by combining the information from the two visions through Kalman filter algorithm. Experimental results prove the feasibility and validity of this algorithm which improves the accuracy of medium-and-long-distance object location. Related Articles | Metrics

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Development of Parametric Design and Motion Simulation System of Elliptical Type Gears JIANG Yan-cang, TIAN Fang-yong, HU Chi-bing 2011, 32(3): 13-16.  Abstract ( 123 )   PDF (555KB) ( 329 )   Calculation and design of non-circular gears are complex and difficult because of their non-circular pitch curves and current three-dimensional design software can not directly realize the modeling of non-circular gears. According to non-circular gear design theory, an elliptical type gear parametric design and motion simulation system is designed through secondary development of SolidWorks by using Visual Basic 6.0, through which the 3D parametric modeling and motion simulation of elliptical type gears can be realized. The system development process is discussed in the paper, and application examples show that the system is of user-friendly interface and correct design. The complexity of calculation and the difficulty of 3D modeling in elliptical type gears design are solved. This system can improve design precision, shorten the development cycle, and guarantee the quality of products. Related Articles | Metrics

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Automatic Generation of 3D Model Based on Sketch LIU Xiao-ping, WU Zheng, LI Lin 2011, 32(3): 17-22.  Abstract ( 112 )   PDF (473KB) ( 225 )   Creating 3D model based on sketch is an emerging research that changes traditional modeling pattern. Two algorithms of automatic generation of 3D model based on 2D curve sketching are introduced and discussed in detail in this paper. The first one expands the curve based barycenter, then reconstructs a mesh from curve-cluster, which, however, is limited in application to only ellipse-like topology curves. The second one finds its axis using discrete method, so more diversified models focusing on details can be generated. The comparison of realization effects of the two algorithms shows that they are effective for fast generation of 3D. Finally, several cartoon models created by the algorithms are displayed, and generation of model animation are desired for further. Related Articles | Metrics

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Evaluating for Composite Position Error of Hole Group Supported by Genetic Algorithm ZHANG Xiao-ping, WANG Jun-ze, ZHOU Sheng-hua 2011, 32(3): 23-27.  Abstract ( 82 )   PDF (607KB) ( 160 )   In the evaluating process of hole group composite position error, the traditional numerical optimization methods are generally difficult to find an ideal location for the geometric frame to meet the minimum condition criterion, especially when the position tolerance follows the principle of MMC and the measured features still do not reach the minimum material size, parts judged unqualified may also be repaired. Aiming at solving the above-mentioned problems, the adaptive genetic algorithm is proposed to search the best location for geometric frame globally, and at the same time, the error compensation due to following MMC principle is taken into account while searching. In addition, the repair-ability judgment and correction calculation are also carried out against failed parts, which will further reduce the false rejection. Related Articles | Metrics

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Two Properties and Point Control of Bivariate Rational Interpolating Surface LU Hai-bo, DENG Si-qing, FANG Kui, XIE Jin 2011, 32(3): 28-34.  Abstract ( 122 )   PDF (563KB) ( 194 )   A bivariate rational interpolation spline with parameters was created in an earlier work which was based on function values only, and this spline is a rational one with biquartic numerator and biquadratic denominator. This paper discusses the spline’s boundary property, the approximation expression of the interpolation and the point control method of the interpolating surface. It is proved that the values of the interpolating function in the interpolation region are bounded no matter what the parameters might be, which is called the boundary property of the interpolation. Also, the approximation expression of the interpolation are derived, which does not depend on the parameters. More important is that the values of the interpolating function at any point in the interpolating region can be modified under the condition that the interpolating data are not changed by selecting the suitable parameters, so the interpolation surface can be modified for the given interpolation data when needed in practical design. Related Articles | Metrics

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Extension of Cubic DP Surfaces over Triangular Domain WU Xiao-qin, TANG Yun-mei, HAN Xu-li 2011, 32(3): 35-40.  Abstract ( 98 )   PDF (612KB) ( 218 )   A Class of quartic DP blending functions with two shape parameters is presented, which is an extension of the cubic DP basis functions defined over the triangular domain; Properties of this new blending function are analyzed and the quartic DP parametric surface with two shape parameters over the triangular domain is defined. The surfaces' properties are similar with the cubic DP parametric surfaces. In particular, when the two shape parameters vanish, they degenerate to the cubic DP basis functions and the cubic DP parametric surfaces individually; by changing the two shape parameters, the shape of surface can be adjusted both wholly and locally in invariable control net. Related Articles | Metrics

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An Optimal Fairing Algorithm for Parametric Cubic Spline Curves ZHANG Hu-dong 2011, 32(3): 41-44.  Abstract ( 135 )   PDF (431KB) ( 273 )   An optimal fairing algorithm for planar parametric cubic spline curves is proposed based on revising gene and revising angle. Faired point can be obtained by resolving a objective function of containing modifying gene  and revising angle  and faired curves is obtained by interpolating the faired point. The purpose of this algorithm is to make the change of curvature of faired curves more gradual and its deviation from the initial curves smaller. It is shown that the algorithm is simply facile and needs a smaller calculation. Related Articles | Metrics

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The Three-Dimensional Fast Segmentation Algorithm Based on Level Set Method SUN Hai-peng, YU Wei-wei, XI Ping 2011, 32(3): 45-51.  Abstract ( 95 )   PDF (893KB) ( 235 )   Because of the large volume of medical image data, the impact of noise, blurred boundaries and other reasons, the three-dimensional segmentation process is time-consuming, and easily produces less or over segmentation. To solve the above problems, this paper proposes a three-dimensional fast segmentation algorithm based on Level Set, using Level Set Fast Marching Method to obtain two-dimensional segmental region, optimizing the boundary contour, using the Digital Differential Analyzer method to extract contour pixels, finally introducing the idea of the Scan Line Seed-filling to achieve the three-dimensional fast segmentation. The actual clinical CT images of vertebral segmentation experiment result shows that this method can quickly and accurately separate out the interested area. Related Articles | Metrics

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A New Algorothm for Boundary Tracing SHI Shuang, QU Shi-ru, HE Li 2011, 32(3): 52-56.  Abstract ( 139 )   PDF (398KB) ( 364 )   For the shortcoming of non-single pixels and broken points in the obtained image boundary, a new algorithm for boundary tracing of dual layer boundary region growing is proposed, to search inner-points and outer-points around center-points, to combine the inner-points with upper outer-points, to conduct continuous tracing with the combined points as the center-points in next search. The algorithm takes into account the one-way search from initial points, and can fill the broken points in one tracing process. Thus, it effectively makes up the defects of memory reptile method and eight neighborhood method in tracing embranchment, broken point and thick boundary. The experiments prove its effectiveness. Related Articles | Metrics

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Standardization of 3D Head-face Model from Magnetic Resonance Imaging CHEN Xiao, ZHOU Hong, ZU Yuan-yuan 2011, 32(3): 57-61.  Abstract ( 147 )   PDF (552KB) ( 202 )   A series of 2D images of human head is obtained from magnetic resonance imaging technology. Their boundary coordinates are extracted respectively, and a hierarchical 3D head parameterized model is constructed by fitting contours of all sections with Fourier series. Whereafter, certain feature sections are defined according to main features of human face. Average processing is also taken to several samples based on the principle of facial feature matching. Accordingly, the materialized 3D standard head-face model is constructed, featuring the comprehensive characteristics of specific population. As examples, round-high standard headform is calculated and constructed through 558 samples, as the design basis for head-face equipment. Related Articles | Metrics

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The Study and Practice of Virtual Reality Technology and Virtual Campus#br# ——Take Weifang University Virtual Campus as an Example LI Jun-feng 2011, 32(3): 62-68.  Abstract ( 145 )   PDF (626KB) ( 341 )   Virtual campus study based on the virtual reality technology is the important content of digital campus construction. Take the campus of Weifang University as virtual space, a vivid campus environment is constructed by using pertinent 3D modeling and romance technology, then the structure framework and function module of virtual campus is established. A virtual campus system is constructed by using of virtual reality technology, multimedia technology and network technology, and the interactive navigation and web publication of the virtual campus has been carried out within this system. Related Articles | Metrics

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Real-time Rending for Complex Product Model Based on Octree ZHAO Lei, ZHAO Gang, TAN Dun-ming 2011, 32(3): 69-74.  Abstract ( 159 )   PDF (564KB) ( 305 )   In order to improve the efficiency of real-time rendering, a method to extract the model information of OpenSceneGraph using scene model dividing up and view frustum culling based on Octree is proposed. This method has a better performance when visualizing the detail scene of virtual environment. Pagelod, which is based on DatabasePager, is also applied to implement the dynamic data translation, reduce the I/O overload greatly and satisfy real-time requirement for complex product model in virtual environment under limited hardware resources. Related Articles | Metrics

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Application Research on Virtual Assembly of Tractor’s Front Drive Axle CAO Wen-gang, CHENG Wu-si, SONG Jun 2011, 32(3): 75-81.  Abstract ( 168 )   PDF (767KB) ( 198 )   This paper analyzes and summarizes the current status of the virtual assembly technology research and elaborates its principle and implementing process. By taking the tractor’s front drive axle as an object, a virtual assembly and its corresponding inspection is conducted in the computer virtual environment (Division Mockup). The generation assembly orders and routes are introduced. The procedure of assembly animation is set up to vividly exhibit the whole process of product assembly. By virtue of the third-party plug-in units and the virtual reality environment consisting of data gloves, polarization glasses, projection system, and position tracker (FOB), human-computer interaction can be achieved in Division Mockup. The rules and methods of human-computer interaction interface definitions are introduced as well. Related Articles | Metrics

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Division of Flow Field Topological Regions through Voronoi Diagram MA Yu-jie 2011, 32(3): 82-85.  Abstract ( 118 )   PDF (473KB) ( 223 )   Topology analysis method of feature-based visualization can show quickly the overall structure of flow field, and is of a greater superiority in focusing on the special structure of the flow field. However, in many cases, it is not enough to only show the structure of the flow field, we also want to know the topological region in detail. Traditional methods to determine the topological region are based on the imaginary part of feature vector, but these approaches are too general, and, because the area size is only relative, it doesn’t consider the impact of the near critical points to the surrounding fluid. In order to show truly the impact of the critical points to around flow movement, Voronoi diagram is proposed to divide the topological region, and the method has been applied to ocean flow fields. Compared to the traditional feature vectors method and proved through experiments, it can achieve better results. Related Articles | Metrics

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A Dicussion of Engineering Graphics Curriculum Reform in Higher Engineering Education System XU Jian, ZHANG Cheng-pu, DING Bai-hui, XU Hui, YANG Lin 2011, 32(3): 86-90.  Abstract ( 126 )   PDF (423KB) ( 274 )   How to set up the reform direction of the engineering graphics courses in the higher engineering education system fitting China's national situation is discussed, to give prominence to features so as to enhance graphics education status in higher engineering education, to include cultivation of the abilities of ideation, creativity, and practice as a primary goal of engineering graphics education reform. The implementation of a series of pilot projects in engineering graphics courses, such as solid modeling and projection, shaft parts mapping and the three-dimensional entity modeling of industrial robot drive, plays an import role for students to improve projection drawing ability, master scientific way of thinking, enhance awareness of engineering and innovation. Related Articles | Metrics

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Engineering Drawing System Reform Based on the TRIZ Education Theory ZHOU Qin, YU Jia, LI Wei-qing 2011, 32(3): 91-94.  Abstract ( 121 )   PDF (372KB) ( 223 )   In order to overcome the shortages of innovation education in the present teaching and improve the innovation capability of students, TRIZ education theory is adopted to analyze the problems and shortcomings of Engineering Drawing course system. Some scientific principles and methods, such as segmentation, merging, anti-weight etc., are used to solve the main contradictions of the course system. Many weaknesses of teaching contents, teaching methods and practice system are overcome. A new innovative system of Engineering Drawing system is built to enhance the capability of solving creative problems of students. Related Articles | Metrics

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A New Method to Recover 3D Object from 2D Views HOU Hong-sheng, YAN-Guan, GU Yan-hua 2011, 32(3): 95-99.  Abstract ( 137 )   PDF (2809KB) ( 291 )   Based on teaching practice in the courses of Engineering Graphics and 3D CAD, a new method integrating traditional 2D drawing with modern 3D modeling is proposed, which uses 3D CAD modeling principle, method and modeling processing in the understanding of 2D view. The method is superior for students to rapidly recover the solid special object shape from 2D view, and to understand the optimal solid modeling and processing. It lays foundation for 3D CAD modeling design. Related Articles | Metrics

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Application of Minimum-Deviation Method to Mechanical Multi-objective Optimal Design WEI Feng-tao, SONG Li, LI Yan 2011, 32(3): 100-104.  Abstract ( 120 )   PDF (507KB) ( 204 )   The minimum-deviation method is introduced into the mechanical multi-objective optimal design. Taking a multi-objective optimal design of hydrodynamic sliding bearing as the example and taking the minimization of friction coefficient and heat productivity，and the maximization of load capability as objectives, the minimum-deviation method is adopted to establish the multi-objective optimal mathematical model. The improved genetic algorithm is utilized to solve this multi-objective optimal problem. The solution-seeking process and its results show that the minimum-deviation method can obtain better results than conventional methods in dealing with multi-objective optimal problem and the validity and feasibility of the method is verified. Related Articles | Metrics

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Research on Method of Evaluating Module Clustering for Complex Product Based on D-S Evidence Reasoning LI Jun-peng, CHEN Xing-yu, ZHAO Han 2011, 32(3): 105-109.  Abstract ( 113 )   PDF (405KB) ( 164 )   Module clustering is foundation of modular design for complex product. Its performance counts for much in efficiency of product design, manufacture and assembly. However, the existing methods lack performance evaluation on modules after module clustering. In this paper, D-S evidence theory is adopted to make uncertain and incomplete evaluation on module satisfaction according to assembly complexity, manufacturability, modularity, stability, sculpt ion and compactness. A two-layered evaluation method on module clustering is proposed, and its evaluation accords with process of human thinking and judgment. The agility, validity and rationality of the method have been illustrated by an instance. Related Articles | Metrics