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30 December 2011, Volume 32 Issue 6 Previous Issue    Next Issue

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The Hyperbolic Paraboloid Formed by Two Affine Point Ranges in Space LIU Fu-ping, DING Yong 2011, 32(6): 1-4.  Abstract ( 74 )   PDF (437KB) ( 194 )   Two lines are skew in three-dimensional space and are satisfied with the requirement as the base of two affine point ranges at the same time , the Quadric Surface then formed by connecting the corresponding points is called Hyperbolic Paraboloid. With the help of the orthographic projection method, the features of the graphically representative method of this surface and the variation rule of the intersection line of this surface with a plane are discussed in the paper. Related Articles | Metrics

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CA1040P90L2 Pickup Driving Axle Design ZHANG Xue-chen, ZHANG Tao, ZHANG Hui-Bo 2011, 32(6): 5-8.  Abstract ( 126 )   PDF (526KB) ( 321 )   Driving axle is mainly composed of main reducer, differential device, wheels actuating device and driving axle shell etc. This paper analyzes the structural type, basic parameter selection and design calculation of the main parts of the CA1040P90L2 pickup driving axle, constructs the 3D model of the main parts, accomplishes the 3D design of CA1040P90L2 pickup driving axle, and realizes 3D assembly simulation and dynamic simulation. The parameter modeling of the parts is achieved. Related Articles | Metrics

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A Class of Quasi-quartic Trigonometric Polynomial Bézier Curves with Two Shape Parameters YANG Lian, LI Jun-cheng 2011, 32(6): 9-7.  Abstract ( 59 )   PDF (603KB) ( 167 )   A class of quasi-quartic trigonometric polynomial Bézier curves with two shape parameters of λ1 and λ2 is presented. The trigonometric polynomial curves have the same featurs with traditional quartic Bézier curves, and it can represent exactly some quadratic curves such as the arc of a circle, an ellipse, or a parabola and some transcendental curves such as circular helix without using rational form. Its shape can be adjusted locally or totally through changing the value of the two parameters, and it can approach to the given control polygon from both sides. The G2 and C4 continuity condition of two pieces of curves is discussed. Examples are given to illustrate the new curve in model design. Related Articles | Metrics

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Two Classes of Quintic Generalized Ball Curves with Adustable Shape YAN Lan-lan, ZHANG Wen, WEN Rong-sheng 2011, 32(6): 16-20.  Abstract ( 80 )   PDF (427KB) ( 185 )   Two new classes of curves with shape parameters are defined. The first class of curve contains the quintic Wang-Ball and Said-Ball curves and the curves located between them. The second class of curve contains the quintic Said-Ball and Bézier curves and the curves located between them. By analyzing the relationship between the new curves and the quintic Bézier curve, the geometric meaning of shape parameters are obtained, and the geometrical drawing method of the new curves are given. Related Articles | Metrics

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Research on the Shape Feature Description in Trademark Retrieval DENG Xue-xiong, YANG Zhi-cheng, ZHU Zheng-hai 2011, 32(6): 21-24.  Abstract ( 90 )   PDF (437KB) ( 253 )   For the problem of “semantic gap” in image retrieval, taking the trademark images as a research object, the natural, abstract and deriving meanings of the Latin letters are analyzed, and a set of “Latin letters descriptors” is constructed. At the same time, the origin, composition and features of the trademarks are analyzed. A method of using “Latin letters descriptors” to describe and encode the trademarks is proposed. A series of search results and the statistical data show that this method is of some practical significance. Related Articles | Metrics

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3D Segmentation of IVUS Image Sequence Based on Snake Model SUN Zheng, YANG Yu 2011, 32(6): 25-32.  Abstract ( 123 )   PDF (741KB) ( 240 )   A 3D parallel method is proposed for segmenting intravascular ultrasound (IVUS) image sequence to extract vessel wall borders based on snake model. Firstly, original images are preprocessed to reduce possible noises and suppress ring-down artifacts. Then, four IVUS longitudinal cuts are obtained where lumen and media-adventitia borders are detected. Once these borders are mapped onto each cross-sectional slice, initial contours in each IVUS frame are obtained. Finally, these initial contours evolve continuously through minimization of a snake energy function until stop at target borders. Consequently, segmentation of each IVUS frame is implemented simultaneously and the efficiency is greatly raised compared with 2D sequential segmentation approaches. The proposed method is experimentally evaluated in large datasets of IVUS images clinically derived from human coronary arteries. Results demonstrate that IVUS images can be automatically, quickly and reliably segmented with the method. Related Articles | Metrics

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Retinex Model in Discrete Cosine Transform Domain for Image Enhancement ZHANG Xin-long, SHEN Yong, ZHANG Xuan, WANG Rong-gui 2011, 32(6): 33-42.  Abstract ( 92 )   PDF (820KB) ( 189 )   Existing image enhancement algorithms by using of Discrete Cosine Transform mostly treat the DCT coefficients uniformly, and can not inhibit artifacts. By introducing Retinex idea into DCT, a new enhancement algorithm is proposed. The algorithm divides DCT coefficients into illumination component and reflection component. The dynamic range of illumination component is mapped to an ideal range, using a function with strong light bating. The local details of reflection component are enhanced by defining a band limited contrast measure. The block artifacts will be suppressed using a block decomposing method. Compared to MSR and DCT enhancement algorithms, results verify this approach’s efficiency of details enhancement and strong light bating, also with artifacts suppressed. Related Articles | Metrics

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Color Image Edge Detection Based on Mathematical Morphology WANG Jin-feng, JIAO Bin-liang 2011, 32(6): 43-46.  Abstract ( 113 )   PDF (464KB) ( 283 )   The traditional edge detection methods have high sensitivities to noise, a novel color image edge detection algorithm based on mathematical morphology is proposed. Gray-scale morphology is extended to color image by sorting each pixel as a vector in RGB space. And then by analyzing the characteristics of the noise (mainly salt and pepper noise) contaminating image, color image morphological basic operators are improved. Improved operators are insensitive to noise and can directly achieve edge detection. Experimental results show that this algorithm can more effectively suppress noise on the impact of edge detection and better preserve edge image details than traditional methods. Related Articles | Metrics

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Research on Objective Quality Assessment of Remote Sensing Image HE Zhong-xiang, WANG Ming-fu, YANG Shi-hong, WU Qin-zhang 2011, 32(6): 47-52.  Abstract ( 110 )   PDF (479KB) ( 411 )   To study the quality effect of the remote sensing image brought by the image compression process, several algorithms of objective quality assessment about the visual and geometric quality of the remote sensing image are discussed. A sub-pixel level corner detection algorithm based on the Harria corner detection algorithm is improved. Two compression algorithms of JPEG2000 and SPIHT are used to verify these assessment algorithms. The experimental results show that the image compression rate can be no larger than 16 if you want to distinguish the details by your eyes, and it can be no larger than 8 if you need satisfactory precision in computer vision applications. Related Articles | Metrics

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Stability Improvement of Face Recognition Algorithm in Video Monitor CHEN Hao, HUO Xing 2011, 32(6): 53-56.  Abstract ( 66 )   PDF (476KB) ( 332 )   Most of the traditional face detecting algorithms recognize face only in a static image and ignore the important relationship between video frames and that will lead to unstable results. This paper improves the face recognition algorithm according to the relationship between video frames and applies it to a video monitor product. Experiments show that the improved algorithm enhances the stability of recognition result and has a preferable application value. Related Articles | Metrics

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Geometric Model Parameters Optimization and Simulation in ADAMS of Movable Roller Harmonic Gear Reducer TIAN Lin, XU Shi-jie 2011, 32(6): 57-62.  Abstract ( 94 )   PDF (568KB) ( 260 )   Harmonic gear reducer is a new kind of transmission device with compact structure and complicated motion transfer process. Aiming to understand harmonic gear reducer intuitionally, a geometric model is established according to the example of movable roller harmonic gear reducer which attracts little attention. Several key parameters are optimized by numeric calculation. According to the geometric model and optimization result, a solid model is developed in ADAMS. Simulation taking two instances of constant and sinusoidal speed command into account is done in ADAMS. The numeric simulation result is coincident with the geometric model and reflects the transmission characteristics of harmonic gear reducer vividly. The study lays a foundation for modeling of transmission system containing harmonic gear reducer. Related Articles | Metrics

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Method of Creating Camouflage Physiognomy for a Local Region ZHAO Min-rong, ZHANG Xi-wen 2011, 32(6): 62-65.  Abstract ( 78 )   PDF (413KB) ( 203 )   Due to the application of the fractal technology in target recognition, traditional camouflage means can not meet the requirement of camouflage defence in modern information condition any more. This paper presents a method of creating camouflage physiognomy for a local battlefield based on the fractal technology. The method chooses the region with typical physiognomy features as an antetype and constructs the physiognomy creating model. The fractal technology is used in the creation of random fractal surface. To achieve its randomicity, the camouflage of the region is realized by syncretizing the physiognomy model surface and the fractal surface with certain coefficient. Experimental results show that using this method can realize good syncretization of the camouflage region with the physiognomy of the battlefields around, which is of good camouflage effect. Related Articles | Metrics

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A Study and Practice of Introducing 3D Modeling into Engineering Graphics by a Merge-integrated Method WANG Jing, LIU Yang, MENG Guan-jun, TANG Chuan-ling, LI Xue-jing 2011, 32(6): 66-70.  Abstract ( 74 )   PDF (1218KB) ( 201 )   Aimed at how to introduce 3D modeling into engineering graphics properly, a merge-integrated method is presented based on modeling flow in Inventor. The important aspects in the introduction are indicated, including sticking to the integrity of the teaching system and subsidiary effects of software, taking the modeling strategy as key points, laying equal stress on hand drawing, instrument drawing and 3D modeling, and merging the software’s rules with national standards of mechanical drawing. The students’ abilities of configuring, drawing and modeling were improved through teaching practice. Related Articles | Metrics

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Analysis on the Thinking Mode in Reading Views TANG Chu-jian, LONG Yu 2011, 32(6): 71-76.  Abstract ( 63 )   PDF (517KB) ( 204 )   Revealing their internal properties is the basis for a natural, deep and full understanding of the relationship between views and objects. This paper adopts two used methods of “line-surface analysis” and “shape analysis” to analyze the thinking process of reading views from micro and macro perspectives, and indicates that the imagery and abstract thinking modes are the basic ones in reading views through the analysis of the thinking object and tools in reading drawings. The paper conducts a deep study of the natural and inherent basic thinking features of interactivity and dynamics in reading views in both drawing and text manners. Related Articles | Metrics

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A Study of Special Effect Simulation Based on GPU-supporting Particle System Editor CHEN Xian-jun, LI Xin-ying, ZHAN Yong-song 2011, 32(6): 77-81.  Abstract ( 73 )   PDF (506KB) ( 227 )   With the issue that traditional special effect simulation using particle system in computer games makes a lot of problems, such as low controllability and high cost, a novel approach is proposed based on particle system editor supported by GPU. The controllability of special effect design can be enhanced by the particle system editor, and the rendering of large amount of particles can be fulfilled in real time by GPU. Experimental results show that the system improves the efficiency of special effect design for computer games greatly. Related Articles | Metrics

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The Algorithm and Implementation of Picking 3D Figure by Web3D Engine CHEN Yu, LIN Wei 2011, 32(6): 82-88.  Abstract ( 75 )   PDF (625KB) ( 195 )   Since computer simulation systems and virtual reality systems developed by the application of Web3D engine needs to run in a Web browser, downloading and running these systems shall be fast. It requires that the calculation speed of Web3D engine including picking function shall be improved as far as possible. A hierarchical algorithm of rays intersection is presented. The first layer is a rapid object selection by AABB algorithm, the second layer is the improvement to the picking precision by triangle algorithm. Based on the proposed algorithm, the picking function of selecting figure object is implemented on an open source Web3D engine by JAVA language. Related Articles | Metrics