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30 June 2015, Volume 35 Issue 3 Previous Issue    Next Issue

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Beautification of Wireframe Model of Three-Dimensional Objects Based on Parallel and Vertical Linear Relationship He Bo, Gao Mantun, Wang Shuxia 2014, 35(3): 325-329.  Abstract ( 121 )   PDF (644KB) ( 197 )   In order to solve the problem that errors may exist in the geometrical interpretation of the relationship between the lines and thus result in the inadequacy in visual expression, a method is developed on parallel and vertical linear relationship for beautifying the wireframe model of three-dimensional objects. Firstly, the ridge direction vector of the three-dimensional wireframe models in the face projection space is calculated and a benchmark ridge is chosen; then geometric errors appearing in wireframe model are corrected by the parallel and vertical constraint of the linear relationship, the corrected ridge is reselected as the new benchmark and a repeatition of the operation is conducted. Finally, the new coordinates of the vertices of the three-dimensional wireframe models are calculated according to the new ridge parameter. The numerical example shows that the proposed methods can effectively solve the parallel and vertical geometric problems in the wireframe model to beautify the wireframe model. Related Articles | Metrics

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The Animated Character Data Conversion Tool for User-Defined Format Nie Wenchao, Li Lin, Liu Xiaoping 2014, 35(3): 330-335.  Abstract ( 112 )   PDF (5077KB) ( 274 )   In order to use the animated character data from common modeling software to research on animated character algorithm more sufficiently, an animated character data conversion tool is developed. This conversion tool includes an export module and an import one. Through analysis of the animated character’s data structure in 3ds max, based on max SDK, in the export module, some secondary developments are done to export the data in 3ds max to an user-defined formatted file which is used to store the information of the animated character, so that the user can do their research on mesh and data merge of the animated character with the exported formatted file easily. In the import module, the max SDK is used to import and reconstruct the animated character from the data in the user-defined formatted file, so that the user can observe the animated character after processing by their algorithm in 3ds max conveniently. The animated character data conversion tool greatly reduces the burdens on the researchers and that makes the researchers be able to concentrate on researching the algorithm of the most essential data of the animated character without considering reconstructing and rendering the data. Related Articles | Metrics

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An Image Restoration Algorithm Based on Structure and Texture Synthesis with Reconstruction of Significant Structure of Images Zhu Xiaolin, Chen Xiaodong, Zhu Yuanzhu, Chen Man, Li Xueyan 2014, 35(3): 336-341.  Abstract ( 125 )   PDF (929KB) ( 338 )   This paper presents an image restoration algorithm by integrating structure and texture features with reconstruction of significant structure of images. Firstly, the algorithm splits the fine structures and large areas in the damaged image using morphological operators. Secondly, the rapid structural restoration algorithm is used for image inpainting. Thirdly, significant structures in the image are reconstructed by interpolation. Finally, the large damaged areas are restored by the weighted matching image restoration algorithm based on the modified priority. For the damaged image with significant structure and texture, the experimental results show the better restoration result and less time consuming of the proposed algorithm than that of the traditional algorithms. Related Articles | Metrics

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Occulusion Enhanced Maximum Intensity Projection Algorithm LuoYuetong, Zhu Huiguo, Han Juan, Xu Yunyun 2014, 35(3): 343-349.  Abstract ( 96 )   PDF (1160KB) ( 222 )   Occlusion enhanced maximum intensity projection is to solve the problem that maximum intensity projection cant convey occlusion cue correctly. It consists of two steps: firstly, K-Means clusting algorithm is used to extract structure features from MIP result images automatically; and then it adjusts rendering process adaptively according to structure features. Furthermore, the concept of rendering priority is introduced to avoid important features being occluded badly by non-important features, and an algorithm is provided to set rendering priority of structure feature automatically. Test result of several volume data indicates that OEMIP can enhance occlusion cue significantly, and rendering speed is enough for real-time interaction. Related Articles | Metrics

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The Active Contour Model Based on the Principle of Fluid Statics for Grayscale Image Segmentation Huang Wenjun, Fang Lijing 2014, 35(3): 350-357.  Abstract ( 76 )   PDF (1196KB) ( 188 )   The new active contour model for grayscale image segmentation is proposed in this paper. This model bases on the theory of fluid statics. The principle of fluid statics is used to drive the continuous curve which surrounds the objects in a grayscale image. This model is able to segment multiple objects, and able to segment the objects which are in the interior of another object in a grayscale image. This model can control the over-segmentation. Related Articles | Metrics

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3D Face Recognition Using Facial Curves Elastic Matching Pan Renlin, Da Feipeng, Zou Hongyan, Wang Zhaoyang 2014, 35(3): 358-367.  Abstract ( 89 )   PDF (642KB) ( 246 )   A 3D face recognition algorithm based on facial curves elastic matching is presented in this paper. Facial surfaces are approximated with indexed sets of level curves. Firstly, the radial curves emanating from the nose tip are extracted after 3D faces are preprocessed. Secondly, the curves of the probe face match the curves of gallery face using the improved hierarchical matching method and the two curves are matched exploiting the distance between the point and nose tip. Finally, the similarities of different curves are weighted fused according to the different degree influenced by expression as sum similarity which is used for matching. Experiment results verify that the proposed method can obtain better recognition rate, and is robust to occlusion, spikes and expression. Related Articles | Metrics

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Research on 3D Assembly Constraint Solving with Approximate Update Formula of Jacobian Matrix Ding Jianwan, Hou Wenjie, Xiong Tao 2014, 35(3): 368-373.  Abstract ( 133 )   PDF (1919KB) ( 243 )   A new method of approximately updating Jacobian matrix during 3D assembly constraint solving is proposed in this paper. This method principally improves the efficiency of constraints solving based on the approximate update of Jacobian matrix. First, an approximate update formula of Jacobian matrix and its inverse matrix are inserted to the non-linear iterative solution process. After that, the indispensable constraint is put forward, which must be satisfied when using the formulas above. At last, a solution handling row rank defect of Jacobian matrix is introduced via disturbance algorithm description. The methodology presented is implemented in a 3D assembly constraint solving engine, named CBABench. An example given at the end of this paper shows that the method has achieved a considerable effect. Related Articles | Metrics

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A Plane Cubic H-Bézier Spiral Cai Huahui, Liu Bingxiang, Cheng Yan 2014, 35(3): 374-378.  Abstract ( 85 )   PDF (404KB) ( 259 )   Based on the requirement of fairing curves design, a planar cubic H-Bézier spiral with monotone curvature of constant sign is discussed. Since this spiral segment has zero curvature at the beginning point, it is suitable for applications such as highway design where the clothoid has been traditionally used. And since the spiral also contains a shape parameter, it has the advantage of adjustable curve shape. Finally, G2 continuous transition curves between the two lines are constructed by the use of the H-Bézier spirals. Related Articles | Metrics

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esearch on Central Trajectory Extraction of Trajectory Cluster in Terminal Area Zhao Yuandi, Sun He, Wang Jiening, Li Tao 2014, 35(3): 379-386.  Abstract ( 123 )   PDF (1182KB) ( 338 )   In order to create a flight plan precisely and reduce the overload of controller, a novel method of central trajectory extraction based on computational geometry is proposed. Firstly, a 3D point cloud model is generated from the radar data, and then a set of sampling points is calculated through an adaptive sampling method along the flight direction. The graph which is established from the sampling points is optimized in the next step. Finally, the central trajectory curve is generated by uniformization and smooth processings successively. Experiments on real data demonstrate that the proposed method can accurately extract the central trajectory of trajectory cluster in terminal area, and recognize the feature points efficiently. Meanwhile, the proposed method is robust. Related Articles | Metrics

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The Key Technology of Lattice Mold Design of Windshield Glasses in High-Speed Train Song Yuwang, Yang Changhao, Shi Xiaofei, Xi Ping 2014, 35(3): 387-395.  Abstract ( 92 )   PDF (1342KB) ( 193 )   As one kind of surface laminated glasses with thermal bending process in multiple species and small batch, the windshield glasses in high-speed train need to meet the requirements of aerodynamics, visuality and security. The mold design is one of the key technologies to shorten the development cycle and the cost. The lattice mold is preferred to the solid mold and the frame mold comparing with tolerance, weight and cost. The means of lattice mold design based on the general CAD software, leads to high complexity and repeatability. To enhance the designing efficiency and quality, firstly, the approach to calculate and adjust the basic plane is proposed, elaborated by the chart and exemplified by the example. Secondly, the process to get the mold curves is standardized by inputting the boundary position and the numbers. Thus the mold curves are serialized and saved. Lastly, including the functions of calculating the bending distance and inquiring the corner points, the special software is developed based on the proposed approach, applied by the Beijing MingDun technology Ltd. The pictures of the lattice mold and the corresponding windshield glasses are given, which verify the practicability and effectiveness of the proposed approach and the developed software preliminarily. Related Articles | Metrics

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Applications of An Improved Ant Colony Optimization ACO Algorithm in Integrated Process Planning and Scheduling Wang Jinfeng, Fan Xiaoliang, Zong Pengcheng, Wan Shuting 2014, 35(3): 396-401.  Abstract ( 77 )   PDF (411KB) ( 172 )   The improvement of standard ant colony optimization (ACO) strategy is important to improve the quality and efficiency for integrated process planning and scheduling (IPPS). A graph-based optimization model for IPPS is constructed by means of node set, directed arc set/undirected arc set and relation of AND/OR. An improved ACO for IPPS is proposed, which avoids the slow convergence and the local convergence by dynamic pheromone update strategy, and improves the quality by multi-objective optimization strategy. The simulation result demonstrates the validity of the proposed algorithm for IPPS. Related Articles | Metrics

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The Point Cloud Simplification Technology of 3D Optical Measurement Applied on Reverse Engineering Bai Daiping, Li Yanqin, Ding Jing, Yang Yong, Fan Yue 2014, 35(3): 402-407.  Abstract ( 69 )   PDF (673KB) ( 200 )   Facing the questions including hierarchical clustering method and point cloud sampling of the reverse engineering, the classification definitions are conducted and the characteristics of hierarchical clustering method are studied. The key technology including the surface variation and BSP construction are studied, and then the flowchart of algorithm realization are constructed. The blade of hydraulic turbine belonged to a certain Factory is carried on sampling and reverse modeling using this algorithm and Geomagic software. The feasibility of the algorithm is verified by this example. Related Articles | Metrics

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Digital Measurement and Tolerance Evaluation of the Large Stator Blade Casting Shi Keke, Pan Weimin, Guo Zhiqiang, Lei Xianqing, Ye Xin 2014, 35(3): 407-411.  Abstract ( 81 )   PDF (1787KB) ( 220 )   With the rapid development of aviation, aerospace, vessel, automobiles and mold industry, the complex surface digital measurement and the technology of tolerance evaluation plays an increasingly important role in the accuracy of surface machining. Large stator blade casting is carried on digital measuring with a laser tracking measurement device, and the measuring points cloud is denoised and reduced. The measurement points cloud and the theory model are matched. The tolerance evaluation and errors of large stator blade castings are calculated. Results of measurement and the error analysis can be used in the optimization of the clamping position for the large stator blade casting in the subsequent processing, making the machining allowance for each part of the blade be more uniform, and improving the processing efficiency and precision manufacturing effectively. Related Articles | Metrics

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Design and Simulation on the Key Components of Pneumatic Precision Metering Device for Direct Sowing of Rice Bud-sowing Zhang Shun, Xia Junfang, Zhai Jianbo, Zhang Xiumei 2014, 35(3): 412-416.  Abstract ( 78 )   PDF (1722KB) ( 170 )   The sockets and sucking nozzles inside air field of pneumatic metering device are difficult to accurately calculate and analyze. Combined with the production practice, the paper determines the structure parameters and working speed of the socket cylinder-seeder, and uses Pro/E software to build 3D model of socket cylinder-seeder, sockets and sucking nozzles inside air field. CFD software is also used to simulate the inside air field of sucking nozzles and sockets which have three different structure parameters. The simulation shows that the hemispherical socket is better than conical socket and straight socket in theory; the bigger sucking nozzle diameter, the stronger sucking ability, and the better sucking effect. The method is suitable for calculating and simulating complex air field accurately. Related Articles | Metrics

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Research on 3D Product Shape Merging Technology Based on Spherical Harmonic Map Su Jianning, Wu Jianghua, Liu Yun, Zhang Qinwei 2014, 35(3): 417-422.  Abstract ( 101 )   PDF (685KB) ( 205 )   The 3D product shape innovation design has played an important role in product styling design, which is an important way to improve the product competitivity. A new algorithm to realize shape metamorphosis between two products based on Spherical Harmonic Map is presented, which will generate several product shapes. Two 3D product shapes are firstly divided by triangular meshes. Then the meshed product shapes are embedded to a unit sphere and generate the embedding models, which have the same topological structure as their 3D product shapes. By merging two embedded models, a corresponding relation between two shapes can be established. The intermediate shapes between two products are easily generated with the linear interpolation method. An experimental study is presented with merging two different mouse prototypes. The result shows that the algorithm is adapted to the product shape merging, which will have a better application prospect in innovation design of computer aided product styling. Related Articles | Metrics

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Research of Color Scheme for Construction Machine Based on Brand Identity Li Jiangyong 2014, 35(3): 423-428.  Abstract ( 95 )   PDF (2571KB) ( 236 )   To boost corporate brand image of Construction Machines and enhance its competitiveness, this paper proposes the method of color scheme and discusses color scheme issues of brand identity. According to construction machine's color design features and the influences on color scheme, the procedures and methods are discussed based on brand identity. By taking excavator as an example, the color scheme's validity and practicability of construction machine are verified. Related Articles | Metrics

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Local Image Representation and Matching Based on Gaussian-Hermite Moments Zhang Chaoxin, Xi Ping 2014, 35(3): 429-435.  Abstract ( 69 )   PDF (1028KB) ( 355 )   The description of image local features has been the most important part in image registration and image retrieval. In this paper, Gaussian-Hermite moments are studied and their invariants are derived. Due to that the scale parameter does not affect their rotation invariants, a descriptor based on multi-scale Gaussian-Hermite moments is proposed. Finally, the proposed descriptor is tested in a serial experiments with the state-of-the-art methods, and the experimental results show that the proposed descriptor performs much better than the others. Related Articles | Metrics

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Scene Roaming Method of Fisheye Image Based on Viewpoint Correction Zhang Haibin, Yu Ye, Li Lin, Liu Xiaoping 2014, 35(3): 435-441.  Abstract ( 114 )   PDF (831KB) ( 223 )   Since significant distortion exists in fisheye image and it is non-intuitive to represent scene information, a scene roaming method of fisheye image based on viewpoint correction is proposed in this paper. In this method, the hemisphere space represented by fisheye image is taken as the viewing target, through transferring the viewpoint to roam in the hemisphere space, so that different information in the scene is observed intuitively. In this method, a spherical mapping model is build based on fisheye image correction method, and real-time correction of the viewpoints centered at observation area is realized based on the mapping relationship. The roaming is realized through displaying the viewing area after correction in real time during viewpoint changing process. Experimental results show that, real time roaming of spherical space represented by fisheye images can be achieved through the method, and the images displayed during roaming process satisfy the line restriction rule. Related Articles | Metrics

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An Associated Quality Assessment Model of Motion Vector and DCT without Reference Video Wu Lili, Yu Chunyan, Chen Guolong, Zheng Weihong 2014, 35(3): 442-449.  Abstract ( 93 )   PDF (1441KB) ( 305 )   Network video distortion caused by packet loss is a research priority of online video streaming service quality evaluation. An associated quality assessment model of motion vector and DCT without reference video is provided. This model associates the human visual perception caused by network packet loss with the frame type whose packet is lost, the movement state and the richness of texture. This model takes the macro blocks that are lost as the basic study object. And it calculates the motion intenseness by using the macro blocks motion vector and calculates the richness of its texture by using the DCT coefficients. And this model evaluates videos quality objectively by associating the motion vector and DCT without any information of the original video and doesnt need decoding completely. Experimental results show that this model's evaluation results have a good consistency with the subjective evaluation results. Related Articles | Metrics

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Research on the Key Technology of Virtual Disassembly System Based on Force Feedback Li Jia, Hou Wen, Xia Wenwen, Yang Yanfang, Chen Dingfang 2014, 35(3): 450-454.  Abstract ( 121 )   PDF (726KB) ( 235 )   In the development of virtual assembly system, it is generally required to produce as much as possible the feeling of "immersion". In addition to the user good visual feeling, it is also required to increase other senses, such as touch, to a most extent. Therefore, it is particularly important to study the force and tactile feedbacks. In this paper, based on feedback analysis device working principle of PHANTOM Omni power, through the use of VC++ combined with OSG, the pickup of virtual objects and interactive mobile is realized. Focusing on the typical mechanical equipment, the interactive virtual disassembly system is developed based on force feedback, which enables the repair personnel to have the feelings of the most direct and real operation experience of mechanical products and repair scene, and thus improves the quality and efficiency of repair personnel and reduces the training costs. Related Articles | Metrics

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Research on Engineering Graphic Teaching Based on the Mode of Top Talents with Spirit of Innovation Jiang Wenrui, Gong Na 2014, 35(3): 455-458.  Abstract ( 138 )   PDF (922KB) ( 279 )   In this paper, an innovation project on engineering graphic course is proposed to fulfill the cultivationn of top talents with spirit of innovation and increase theefficiency of engineering graphic teaching. The practice is carried on. The bilingual teaching mode is adopted. An engineering graphic experiment course based on innovation configuration design and an experiment course on mechanism design with self-determination and mutual method are carried on. The innovation thought and engineering consciousness of students are trained, theirpractice abilities are exercised, the diathesis of group cooperation is increased, whichlay a good foundation for the learning of professional knowledge. And perfect teaching purpose is obtained. Related Articles | Metrics

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Exploration of Interdisciplinary Comprehensive Industrial Design Teaching Mode Yin Hu 2014, 35(3): 459-463.  Abstract ( 100 )   PDF (1585KB) ( 314 )   Focusing on recombining the curriculum system previously artificially separated into organic interconnected whole, this teaching mode tries to adapt to the trend of comprehensive design discipline, and to establish comprehensive design education system. Emphasizing the design-centric, organic knowledge arrangement enables students to develop integrated design innovation in the learning process of curriculum subjects. The specific teaching link uses research-based teaching mode and course practice based on the research projects of certain subjects, breaking through the traditional teaching mode of imparting knowledge, and establishing student-centered innovative training mode. Professional teachers, business managers and designers explain the innovative concepts of products and case studies from different perspectives, and guide students to carry out the theme research projects scientifically. Related Articles | Metrics

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Three-dimensional CAD Auxiliary Teaching of Engineering Graphics Zhang Shuyan, Lei Guangming, Cheng Bin, Zhang Qing 2014, 35(3): 464-468.  Abstract ( 127 )   PDF (1393KB) ( 285 )   This paper introduces 3D CAD modelling technology in engineering graphics teaching in order to solve the problem that the students' spatial imagination and logical thinking ability is not strong in projection theory teaching. As a new teaching idea, auxiliary teaching with 3D CAD modelling technology can realize students' thinking transformation process of 〝plane-space-plane〞, by adopting the modern teaching means. That is to imagine the shape of the three-dimensional space body by the flat view and then express graphically the body through the view form. Practices have proven that the organic integration of 3D CAD and engineering drawings can not only improve the students abilities of space imagination and configuration, but also enhance their graphics conceptions. Related Articles | Metrics

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Research of Top-Notch Innovative Talents Training Based on the "4S" Model Guo Rui, Tian Yaya, Zhao Jiangyi 2014, 35(3): 469-474.  Abstract ( 133 )   PDF (698KB) ( 200 )   Based on the experience of cultivating engineering applied innovative talents with distinctive features and strong practical ability, the training model depending on the Producing. Education and Research Base is researched. Based on the change of traditional education mindset and ideas, which takes the student as the main body, teacher as dominant, task type teaching as the main line, the overall quality of the students with innovation as the core can be promoted. An education training model is built, which helps the students to be the top-notch innovative talents. The role of the task of teaching is maximized, which makes it an important factor in the talent training environment. The role of the base is given full play to provide good practice conditions for the training of top-notch innovative talents. Related Articles | Metrics

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Design of the Drawing Competition Information System Based on WebGIS Liu Jipeng, Xiao Haihong, Shao Likang 2014, 35(3): 475-480.  Abstract ( 78 )   PDF (7231KB) ( 44 )   Based on the analysis of the topology relationship in the drawing competition information system, a system based on the C/S is designed and the key technology of the main function modules is described. The drawing competition information system is established by WebGIS middleware technology and MapInfo OLE+embedded technology. The production and analysis of the GIS thematic maps of the drawing competition are introduced as well. Related Articles | Metrics

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Hierarchical Analysis and UML State Machine in Disassembly and Assembly Process Simulation Chen Jingjie, Li Huiru, Zeng Xuefeng 2014, 35(3): 481-485.  Abstract ( 74 )   PDF (537KB) ( 211 )   To address the problems of non-simple disassembly and assembly procedure, enormous system models in the Aircraft Maintenance Training System, a process modeling method, combining UML state machine and hierarchical analysis, is presented. UML state machine is used to build models of the state, migration and constraints of the components, to unify specification expression of component model, and to improve the efficiency of modeling. The Hierarchical analysis is used to achieve a logical and orderly presentation. Through real-time monitoring the parts, a high degree of simulation training model is established. Final adoption of virtual disassembly of some Aero-component indicates that the method is feasible. Related Articles | Metrics

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Modeling and Analysis for the Big-hole Leakage Rate of Gas Pipeline Chen Ping, Mei Huafeng, Zhao Hailin 2014, 35(3): 486-489.  Abstract ( 125 )   PDF (621KB) ( 322 )   Through the analysis on the progress of the leakage of gas pipeline，the calculating models of big-hole leakage are established. Based on the leakage process of big-hole，the three kinds of state are discussed and analyzed. It is testified that, under the situations of high-pressure, there only exist two possible states, which are sub-critical flow in pipe and critical flow in orifice, or critical flow in pipe and orifice. While in the case of low and medium pressure, there only exists sub-critical flow in pipe, critical flow in orifice and sub-critical flow in pipe and orifice. The rate of leakage at different points is also analyzed. The leaky rate of different hole diameters can be well calculated by the models in the paper, and it provides basis for quantitative risk assessment of long gas pipeline. Related Articles | Metrics