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31 December 2010, Volume 31 Issue 6 Previous Issue    Next Issue

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Cognition to the Discipline of Engineering Graphics and the Discipline of Graphics TONG Bing-shu 2010, 31(6): 1-6.  Abstract ( 163 )   PDF (380KB) ( 303 )   Because “graphics” is the research object for both disciplines of “engineering graphics” and “graphics”, so “graphics” is discussed from its two sides of “shapes” and “pictures” in detail. Three kinds of “shapes” and “pictures” are concluded, and then the differences of research objects for both disciplines are pointed out. Through investigating some definitions for both disciplines, the new definitions are presented. Meanwhile the branches and corresponding subjects in each branch are put forward for both disciplines. Related Articles | Metrics

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Study on the Reasonable Annotation and the Application of the Maximum Slope Line in Graphics Theory LEI Fang 2010, 31(6): 7-11.  Abstract ( 128 )   PDF (603KB) ( 261 )   The study of the maximum slope line in the engineering graphics is quite less, for its geometry definition and mapping process are abstract and obscure, but it is frequently used in the architectural design and the engineering drawing. The process of carrying out more accurate definition analysis and space discussion, increasing with the engineering examples, three-dimensional visualization will help to deepen the concept, broaden horizons and strengthen the effective convergence of the graphics-based theory and the following expertise. Related Articles | Metrics

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Realization of the Function of GIS Layer’s Processing with MapObjects YU Wei-yi, HU Hong, CHEN Chun-xiang 2010, 31(6): 12-18.  Abstract ( 102 )   PDF (490KB) ( 210 )   To avoid the complexity of special GIS software, this paper, taking the GIS layer processing module in a campus ground object resources’ administration system based on MapObjects for instance, discusses the method of how to realize the function of GIS layer’s processing. The effective programme can help users to complete the processing of vectorgraph layers easily, improve the efficiency greatly. The experiment results showed that the MapObjects’s functions are very suitable for processing geographic information, and is of strong advantage. Related Articles | Metrics

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The Designing Methods of Fish-eye Distortion Correction Using Latitude-longitude Projection YANG Ling, CHENG Yun 2010, 31(6): 19-22.  Abstract ( 459 )   PDF (485KB) ( 2668 )   For correcting the distortion caused by fish-eye lens, this paper proposes fish-eye distortion correction methods using Latitude-longitude projection image. The paper deduces the mathematic basis of eliminating distortion, summarizes and proposes a efficient fish-eye image distortion correction algorithm without any marking data. The use of Latitude-longitude image correction method can reduce the distortion of image in the way of projecting the distorted hemispheric fish-eye images into square shape as general photos, which greatly satisfies the practical requests. Related Articles | Metrics

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High Accuracy Motion Estimation Method Used for Three Dimensional Reconstructing from Two Views CAI Tao, DUAN Shan-xu, LI De-hua 2010, 31(6): 23-28.  Abstract ( 128 )   PDF (714KB) ( 215 )   Recovering the 3D geometric structure of an observed object from its two perspective views is one of the most important tasks in the computer vision research. It’s well known that the accuracy of 3D reconstruction is mainly decided by the performance of motion estimation method. In the paper, the fundamental model of two-view imaging system is introduced and the principles and disadvantages of some motion estimation methods are analyzed. To improve the estimation accuracy, a modified non-linear iterative optimization method is proposed based on the projective error minimization. The numerical simulations prove that the estimation accuracy is improved either under large translation and small rotation or under small translation and large rotation. Furthermore, the proposed method is verified by reconstruction from two view images of simulated object and real object. The result shows that the metric error is below 2% and the angle error below 3°. Related Articles | Metrics

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An Improved Method of Hough Transform Circle Detection Based on the Midpoint Circle-Producing Algorithm ZHU Xiao-lin,GAO Cheng-hui,HE Bing-wei, HUANG Min-chun, CHEN Jie 2010, 31(6): 29-33.  Abstract ( 145 )   PDF (499KB) ( 224 )   To conduct vision detection to the circle’s geometric feature of the machine parts’ images, a new circle detection method is put forward by joining the midpoint circle-producing algorithm and Hough transform, which improves the floating calculating of the midpoint circle-producing algorithm and other. The detailed implementation steps are given and the detection results show that the new method is feasible. Finally, the experimental comparison indicates that the proposed method is effective. Related Articles | Metrics

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An Algorithm to Deal with Boundary of Meshes with Loop Subdivision Wavelets ZHAO Gang, JI Bao-peng, BAI Jie 2010, 31(6): 34-38.  Abstract ( 150 )   PDF (604KB) ( 172 )   Subdivision wavelets have been developed very fast in recent years. They are widely used in computer graphics, progressive transmission and multiresolution editing etc. Based on the lifting scheme, Bertram has introduced a bi-orthogonal wavelet construction for the Loop subdivision. The vertexes involved in the Bertram’s method are all inner ones in the subdivision surface. The paper presents a method to deal with the boundary of the mesh with subdivision wavelets. Tests show the feasibility of the approach. Related Articles | Metrics

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Algebraic Trigonometric Blending Bézier-type Interpolation Curves SU Ben-yue, SHENG Min 2010, 31(6): 39-44.  Abstract ( 124 )   PDF (414KB) ( 187 )   A class of C2 continuous algebraic trigonometric blending Bézier-type interpolation curves is constructed based on the definition of free form algebraic trigonometric blending Bézier-type curves. The introduced curves inherit some characteristics which the Bézier interpolation curves have. Meanwhile, the new curves can accurately represent some conic and transcendental curves, which are more powerful than the Bézier interpolation curves. Moreover, the shapes of curves can be adjusted freely by an introduced control parameter in the base functions. At last, the illustrations show that the new interpolating curves are effective in practice on geometric modeling. Related Articles | Metrics

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Adjustable Quadratic and Cubic Bézier Curves with Given Tangent Polygons LIU Zhi, TAN Jie-qing, CHEN Xiao-yan, ZHANG Li, SHI Jun 2010, 31(6): 45-50.  Abstract ( 119 )   PDF (454KB) ( 162 )   This paper proposes an approach to constructing planar piecewise quadratic and cubic Bézier curve with all edges tangent to a given polygon and the curve segments are joined together with C1-continuity. The segmented Bézier curves are all shape preserving to their tangent polygon. All control points of the Bézier curve segments can be calculated simply by the vertices of the given polygon. The curve can locally or globally approximate the tangent polygon by the adjustment of the control parameters. Experiments show that the method given in this paper is simple, intuitive, effective and easy to control. Related Articles | Metrics

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Curve Reconstruction Using Line Segment Based on Growing Cell Structures WANG Shi-dong, ZHANG You-sheng, WANG Huan-bao 2010, 31(6): 51-55.  Abstract ( 111 )   PDF (454KB) ( 254 )   The study of curve reconstruction based on unorganized data points has great importance in reverse engineering. Curve can be reconstructed with line segment Approximation. The paper presents a new algorithm based on growing cell structures to realize curve reconstruction using line segment.Given a set of unorganized data points and an initial polygonal line, the vertex position of polygonal line can be optimized by using the algorithm to make the vertexes of polygonal line gradually approach the given unorganized data points. In order to make the vertexes of polygonal line distribution coincide the space distribution of unorganized data points, the vertexes which are very active are split and which are least active are deleted continually. Experiment results are given which show that the new algorithm is quite effective. Related Articles | Metrics

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Tooth Surface Reconstruction by Catmull-Clark Subdivision and Mesh Modification WANG Yu-hui, ZHANG Yu-ru 2010, 31(6): 56-62.  Abstract ( 119 )   PDF (580KB) ( 171 )   Bounding box of data points are obtained according to data points of tooth surface, based on which initial control meshes are constructed. The limit points of Catmull-Clark subdivision are calculated by the expression derived by means of matrix diagonalization. Vertexes of control mesh are moved in order that each limit point approximates to its data point. Then subdivision and modification of the meshes are applied repeatedly so that the mesh at each level becomes deformed gradually under the “guide” of points to approximate to data points of tooth surface. Thus the three-dimensional reconstruction of tooth model is achieved. Related Articles | Metrics

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Image Colorization Based on p-Laplace Equation WANG Ze-wen, ZHANG Xiao-ming 2010, 31(6): 62-67.  Abstract ( 143 )   PDF (697KB) ( 186 )   Colorization of grayscale image is a challenging research field in image processing, and has wide application prospect. After analyzing current colorization algorithms, the paper proposes a new colorization algorithm based on p-Laplace equation. A user needs to provide the grayscale image with a few color scribbles manually. Then, the grayscale image is colorized by solving the p-Laplace equation. Since the p-Laplace operator is a nonlinear anisotropic diffusion operator, the new method can better maintain the color’s effect of the edge, at the same time achieving the color expansion than Saprio’s poisson colorization algorithm and Teng sheng-hua’s Laplace colorization algorithm, which are also partial differential equation based methods. Related Articles | Metrics

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Cutaway View Processing in 3D Solid Reconstruction WANG Xiang, DING Yun-liang, LI Jing 2010, 31(6): 68-74.  Abstract ( 126 )   PDF (604KB) ( 201 )   Through providing extra information, cutaway view aids engineering view understanding and accelerates the 3D reconstruction process. This paper proposes a processing algorithm in 3D reconstruction based on the analysis of cutaway view features: to use the cutaway view information to intelligently fetch the basic entity, then to conduct Boolean operation on the basic entity and the reference object generated from view silhouette, and in this way to get the target object. The algorithm can process full cutaway views, half cutaway views and parallel cutaway views. Examples are provided to identify its feasibility in the paper. Related Articles | Metrics

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Research on Computer Aided Visible Design Method for Lightning Protection Scope CHEN Ling-ling, CHEN Chi-kun 2010, 31(6): 75-79.  Abstract ( 148 )   PDF (430KB) ( 178 )   The traditional method of lightning protection scope design has many disadvantages, such as low efficiency and precision, and mistakes are very easy to be made in the drawing and calculating of the design. According to the characteristics of the thunder and lightning protection in South China, a visible design method of lightning protection scope based on AutoCAD is researched. An improved method is provided in order to avoid the repetitious counting by using the existing algorithm, which covers the cases of any number and different height of lightning rods, and computational efficiency is increased. Related Articles | Metrics

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Research and Development on Parameterized Design System of Truck Crane Arm GUO Ke-xi, LI Guo-zhi, YANG Wei 2010, 31(6): 80-84.  Abstract ( 147 )   PDF (467KB) ( 234 )   According to the interrelation characteristic of the structure size of the crane arms, the size actuation method is used, the parameterized design system of truck crane arms is developed based on the re-developing of the 3D software SolidWorks with VB language. 3D model of the arms of truck crane can be quickly structured through inputing the cross-sectional size of the basic jib and the number of booms of the crane in the system, it accomplishes the automation and serialization of designing of the arms, and hence reduces the development cycle, and enhances observably the efficiency and quality in truck crane design. Related Articles | Metrics

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A New Approach to Calculating Parameter Ranges for Systems of Geometric Constraints ZHANG Xing-li, HU Yun-hong, LU Xin-ming 2010, 31(6): 85-92.  Abstract ( 129 )   PDF (414KB) ( 161 )   In parametric CAD graphic design, it is a common operation to modify the parameters of graph objects to regenerate graphics. Users usually need to repeatedly enter parameter values in the geometric constraint system to get a satisfactory solution. In the process of changing the value of parameters, the allowable parameter values are not known to the user beforehand and there is no guide information, so users have to input the parameter values in a trial-and-error way. This paper introduces structural constraints to the field of interval parameters and proposes an algebraic algorithm for determining the valid ranges of parameter values. The complexity of the algorithm is O(n2). Related Articles | Metrics

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Using ObjectARX to Realize Feature Modeling WEI Yong-le, CHAO Cai-xia 2010, 31(6): 92-99.  Abstract ( 124 )   PDF (585KB) ( 185 )   To meet the requirement of product feature model of integration of CAD/CAM in the medium and small enterprises, the information model of feature is created based on the feature-based modeling theory. The method of realizing feature modeling with AutoCAD is researched, and the primary steps of feature modeling as inputting the feature’s parameters, locating, creating, saving are introduced. The instance of modeling gear pump body testifies the feasibility of using ObjectARX to realize feature modeling, thus providing a simple and effective method of the integration of CAD/CAM for the medium and small enterprises. Related Articles | Metrics

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Parameter Optimization of Female Die Molding in Cold Extrusion of Spur Gear MENG Guan-jun, ZHAO Han, CHEN Ke 2010, 31(6): 100-105.  Abstract ( 132 )   PDF (756KB) ( 171 )   Aimed at the problems of great deformation force and hard corner filling in cold extrusion of spur gear, a geometry model of the streamline female die of spur gear is constructed, based on which numerical simulation of cold extrusion of spur gear is conducted. The results indicate that the streamline female die is effective in improving metal filling in corner under small deformation force. By analyzing the influence of different blank magnifying radius (namely  ) on female die shape and deformation mode in the simulation process, the parameter value of  for a most optimized model is found through numerical simulation of different female dies. Related Articles | Metrics

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Optimizing the Laser Machining Path of DXF File Drawn with Region Graphics HU Sheng-hong 2010, 31(6): 106-110.  Abstract ( 187 )   PDF (333KB) ( 374 )   A DXF file is normally occupied by many disorder graphic elements, which cause numerous vain journeys yet low efficiency in laser machining. With the graphic elements of DXF file as the object, region drawing technology is used to convert those scattered graphics into a list of closed graphic groups. Starting from the origin, the shortest path from current position to the start of next graphic groups is obtained greedily until the optimized path of the whole drawing is achieved. Time complexity of the algorithm is O(n2). The experimental results prove that the proposed algorithm applied to laser curving and cutting can reduce the vacant path and the numbers of turning on or off the laser, and thus improve the efficiency of machining. Related Articles | Metrics

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Research on Assembly Process Planning System for Radar High Power Hinge ZHANG Hong-qi, CHEN Xing-yu, ZHOU Qing, SHU Feng-tao 2010, 31(6): 111-116.  Abstract ( 118 )   PDF (450KB) ( 283 )   Three-dimensional assembly process planning system of radar high power hinge(HPH-CAAP) is put forward and designed facing the requirement of concurrent engineering. Product assemblability is verified and improved by the emulational system using Microsoft Visual C++ 6.0 as developing language and UG/OPEN API as developing tool. The main structure of HPH-CAAP and the key technical modules such as virtual assembly model obtaining, assembly process planning, assembly simulation, interference check and model reconstruction are expounded. The total realization processes of HPH-CAAP’s modules are researched. Finally, an application example of this system is implemented. Related Articles | Metrics

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Interaction Design Methods of Three-dimensional Shoe Pattern LIU Bin, JIANG Kai-yong 2010, 31(6): 117-124.  Abstract ( 147 )   PDF (691KB) ( 224 )   A new discrete representation approach and an interactive editing method for three-dimensional shoe pattern curves generated on triangular meshes of shoe last model are presented. The selection areas of shoe last surface are flattened by utilizing the improved energy model. The topological relation between three-dimensional upper surfaces and two-dimensional flattened upper surfaces is established in the process of flattening. And the real-time association for shoe pattern curves in three-dimensional and two-dimensional flattened spaces is obtained by using the topological relation mentioned. For the convenience of other programs calling, two-dimensional shoe pattern curves generated are represented by cubic non-uniform B-spline and outputted in the DXF format. Numerical results show that the proposed method has advantages of good interaction and real-time intuition, and the method can meet the requirement of real-time interactive design for shoe pattern based on shoe last. Related Articles | Metrics

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Design and Application of Virtual Maintenance Simulation System Based on Virtual Reality Technology CHEN Ke, PENG Wu-si, ZHANG Hong-qi, WANG Rui 2010, 31(6): 125-132.  Abstract ( 137 )   PDF (728KB) ( 364 )   This paper focuses on the product maintainability. It introduces virtual reality technology to the product maintenance operation in the concurrent development mode. That is, maintenance simulation for product in computer-generated virtual reality environment. This paper establishes a virtual maintenance system using passive single three-dimensional protection system as virtual reality environment, employing DELMIA, VRCO VisTool, CDVI, Pro/E soft wares as virtual reality software system. Meantime, it illuminates VR peripheral integration, environmental modeling and data conversion, collision detection, human ergonomic, three-dimensional display and other key technologies. Finally, a sample is given on the validity of the virtual maintenance through certain radar rotating platform maintenance. Related Articles | Metrics

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Multi-Agent Based Ergonomic Simulation and Design System WANG Zhao-hui, ZHENG Guo-lei, ZHU Xin-xiong 2010, 31(6): 133-139.  Abstract ( 127 )   PDF (556KB) ( 217 )   A multi-agent intelligent design system is presented for manufacturing process simulation and products’ ergonomic analysis. The system realizes virtual human’s adaptive behaviors by fuzzy multi-objects decision-making theory. In virtual environment, the intelligent virtual human performs tasks’ operation autonomously and shows optimum posture configuration with ergonomic assessment results in real time. Experimental results of prototype validate the feasibility of this technology. Related Articles | Metrics

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Research on Realization of 3D Visualization of the Underground Pipe in a City CHEN Zi-hui, HU Jian-ping, DONG Chun-hua 2010, 31(6): 139-145.  Abstract ( 180 )   PDF (533KB) ( 395 )   Through analysing the way to realize the 3D pipe visualization model, constructing its digital model, and adopting Flt document, the paper proposes the automatic construction technology of 3D pipe model based on the survey data, blueprint and CAD document format DXF. On the basis of Vega Prime, such Flt models as buildings, underground rock layers and pipes can be introduced to the system and can be driven jointly. Through the above-mentioned technologies, fast modeling of urban underground pipes and 3D visualizational browzing are realized. Related Articles | Metrics

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Research on the Visualization of 3D Symmetric Tensor Fields Based on Surface Icons SONG Wei-jie, CUI Jun-zhi, YE Zheng-lin 2010, 31(6): 146-150.  Abstract ( 124 )   PDF (504KB) ( 240 )   The current surface icon method to visualize a 3D symmetric tensor field just displays the direction of certain eigenvector field of the tensor field, but not its magnitude. The paper presents that rendering 3D isolines and setting color on the surface icons can display the magnitude of the eigenvector field, thus the direction and magnitude of the eigenvector field are displayed simultaneously on the surface icons, which improves the surface icon method of 3D symmetric tensor fields and reveals more completely the information of tensor fields on surfaces. Related Articles | Metrics

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The Effective Integration of 3D Design and Engineering Graphics ZHANG Jing-ying, LUO Hui-fu ZHANG Tong JIAO Yong-he 2010, 31(6): 151-154.  Abstract ( 164 )   PDF (379KB) ( 305 )   Along with the popularization and rapid development of computer software and hardware technology and the growing demand of manufacturing for 2D and 3D design techniques of computer graphics, it is particularly important to blend 2D and 3D design techniques of computer graphics in the teaching of the engineering graphics. The paper introduces the teaching reform and practice of the three-dimensional CAD in Beijing Institute of Technology. Three modes are introduced as the outside hanging mode, the segmentation mode and the fusion mode. The focus is on how to syncretize the three dimensional CAD and engineering graphics effectively. Related Articles | Metrics

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Research on Employment-oriented Study Evaluation System about Engineering Drawing ZHANG Shu-min, CHEN Gang, CHEN Shu-bin 2010, 31(6): 155-160.  Abstract ( 110 )   PDF (427KB) ( 197 )   The teaching evaluation is an important link in the whole teaching activities. In the teaching process, there are many factors, content and results to be evaluated. However, the evaluation on study result is especially critical. According to the process of employment-oriented curriculum development, the paper analyzes the goal and the contents of engineering drawing, compiles the study evaluation criteria and determines its methods and forms. Finally, taking the new textiles mechanical and electrical major as an example, the paper designs the specific study evaluation plan. Related Articles | Metrics

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Research on City Ecological Tunnel Based on Remote Sensing Image Interpretation LI Kun 2010, 31(6): 161-164.  Abstract ( 139 )   PDF (718KB) ( 233 )   Interpretation of Remote Sensing image is the frontier technology in Iconology, which is of interdisciplinary meaning and good effect by using it to do the research on city environment problem. This paper studies the position, form and structure of city ecological tunnels by using the satellite image and does the case study of Beijing city. It also uses the indices of NDVI and surface brightness temperature deduced by satellite image to analyze the function of ecological tunnels. It is proved that Remote Sensing can be used into precise analysis of city environment and is the way for the application of Graphics in Geography and Urban Planning. Related Articles | Metrics

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Data Registration Based on Wavelets in Reverse Engineering WU Wei-yong, WANG Ying-hui 2010, 31(6): 165-170.  Abstract ( 125 )   PDF (628KB) ( 169 )   A new multiresolution Iterative Closest Points (ICP) algorithm is proposed by combining multiresolution features of wavelets analysis and original ICP. The first step is to triangulate the data sets, and wavelets decomposition is performed on the triangulation mesh. In order to obtain the correspondence between the data sets, the discrete curvatures of the mesh are calculated at the lowest level of wavelets decomposition. A pair of points will become the candidates if their curvatures are close enough. Wavelets reconstruction is carried out after iterative registration at each level. Some examples show that the multiresolution ICP algorithm is fast and insensitive to the noise of data sets. Related Articles | Metrics

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Research on Automatic Layout of Wire-harness Connection Graph Based on Force-directed Algorithm XU Ben-zhu, CHENG Guang-chun, LI Zhong-ze, LIU Xiao-ping 2010, 31(6): 171-177.  Abstract ( 195 )   PDF (527KB) ( 480 )   Wire harness connection graph (WHCG), consisting of wire harness segments, is a connected acyclic graph generated from wire harness drawing after removing the wire harness connectors. WHCG, the main component of automatic layout of wire harness drawing, represents the connection of wire harness connectors and determines the layout skeleton of wire harness drawing. The paper introduces the force-directed layout models and algorithms from the undirected graph layout theory into automobile WHCG’s automatic layout, the trunk search algorithm for WHCG and constrained symmetrical layout of wire harness branches are given, based on which the WHCG’s layout is formulated, providing the effective methods and techniques for automatic layout of automobile wire harness drawing. Related Articles | Metrics

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Accessing AutoCAD DWG Graphic Files with DWGDirect YAN Yun, XU Chao 2010, 31(6): 178-181.  Abstract ( 362 )   PDF (344KB) ( 477 )   The data format of AutoCAD DWG files and the main steps for developing the interfaces with DWGDirect C++ Libraries are presented in the paper. DWG file consists of five parts: header, entities, tables, blocks and contingency header, and the information storage of each part is briefly given. DWGDirect, a library developed by the Open Design Alliance, can be used to read and write DWG files without AutoCAD platform. With the method, the realization of how to access part entities for a CAD/CAM software is discussed and a part of C++ codes is introduced also. Related Articles | Metrics

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Implementation of PDM System for Small and Medium-sized Gas Appliance Industry CHEN Jun-yuan, DONG Yu-de, LIU Ji-qing, ZHU Chang-jiang 2010, 31(6): 182-186.  Abstract ( 91 )   PDF (431KB) ( 241 )   The characteristics of small and medium-sized gas appliance enterprises are analyzed. Combined with practical problems of Guangdong Electric Gas Appliances Co., Ltd., the methods of construction and implementation of product data management system are discussed. A Web-based product data management system is developed based on Web with .NET platform and structure query language technology. The structure design scheme, key technology and primary function of the system are given. After system implementation, the material flow of the enterprise is standardized, and the product data is managed based on Web. The system is of moderate flexibility and easy promotion. Related Articles | Metrics

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Finite Element Modal Analysis on Spur Gear CHEN Qing-sheng 2010, 31(6): 187-190.  Abstract ( 156 )   PDF (581KB) ( 292 )   Mechanical model of spur gear is established through 3D design software Pro/E. The model is imported into the ANSYS by the interface for Pro/E and ANSYS. Natural frequencies and corresponding modal shape are to be solved by software ANSYS. The results of modal analysis provide a new technique and provide a reference for the design and improvement of the gear. Related Articles | Metrics

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Digital Watermarking for Engineering Drawing CHEN Yong-fu, ZHAO Jian-jun, CHEN Li-ping 2010, 31(6): 191-197.  Abstract ( 110 )   PDF (618KB) ( 202 )   This paper analyzes the characteristic of digital watermarking of engineering drawing. A perturbation methodology is presented to embed the watermark into engineering drawing through the coding redundant information. The algorithms of embedding watermark into line, arc and circle in engineering drawing and detecting the watermark from them are proposed in this paper. Due to the magnitude of perturbation is very small, the watermark can not be apperceived, and does not influence the function of drawing. Subsequently, the capability of resisting the attack of moving, rotating, zooming, adding and deleting is discussed in theory and practice. Related Articles | Metrics