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ISSN 1000-9000(Print)
/1860-4749(Online)
CN 11-2296/TP
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  • Table of Content
      15 September 2004, Volume 19 Issue 5 Previous Issue    Next Issue
    For Selected: View Abstracts Toggle Thumbnails
    Articles
    Automatic Modeling of Virtual Humans and Body Clothing
    Nadia Magnenat-Thalmann, Hyewon Seo, and Frederic Cordier
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(528KB) ( 3059 )   Chinese Summary
    Highly realistic virtual human models are rapidly becoming commonplace in computer graphics. These models, often represented by complex shape and requiring labor-intensive process, challenge the problem of automatic modeling. The problem and solutions to automatic modeling of animatable virtual humans are studied. Methods for capturing the shape of real people, parameterization techniques for modeling static shape (the variety of human body shapes) and dynamic shape (how the body shape changes as it moves) of virtual humans are classified, summarized and compared. Finally, methods for clothed virtual humans are reviewed.
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    Estimating Subdivision Depth of Catmull-Clark Surfaces
    Hua-Wei Wang and Kai-Huai Qin
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(436KB) ( 1358 )   Chinese Summary
    In this paper, both general and exponential bounds of the distance between a uniform Catmull-Clark surface and its control polyhedron are derived. The exponential bound is independent of the process of subdivision and can be evaluated without recursive subdivision. Based on the exponential bound, we can predict the depth of subdivision within a user-specified error tolerance. This is quite useful and important for pre-computing the subdivision depth of subdivision surfaces in many engineering applications such as surface/surface intersection, mesh generation, numerical control machining and surface rendering.
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    Algebraic Conditions for Classifying the Positional Relationships Between Two Conics and Their Applications
    Yang Liu and Fa-Lai Chen
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(418KB) ( 1695 )   Chinese Summary
    In many fields of computer science such as computer animation, computer graphics, computer aided geometric design and robotics, it is a common problem to detect the positional relationships of several entities. Based on generalized characteristic polynomials and projective transformations, algebraic conditions are derived for detecting the various positional relationships between two planar conics, namely, outer separation, exterior contact, intersection, interior contact and inclusion. Then the results are applied to detecting the positional relationships between a cylinder (or a cone) and a quadric. The criteria is very effective and easier to use than other known methods.
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    PDE Surface Generation with Combined Closed and Non-Closed Form Solutions
    Jian-Jun Zhang and Li-Hua You
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(302KB) ( 2317 )   Chinese Summary
    Partial differential equations (PDEs) combined with suitably chosen boundary conditions are effective in creating free form surfaces. In this paper, a fourth order partial differential equation and boundary conditions up to tangential continuity are introduced. The general solution is divided into a closed form solution and a non-closed form one leading to a mixed solution to the PDE. The obtained solution is applied to a number of surface modelling examples including glass shape design, vase surface creation and arbitrary surface representation.
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    Unified Model in Identity Subspace for Face Recognition
    Pin Liao, Li Shen, Yi-Qiang Chen, and Shu-Chang Liu
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(453KB) ( 1424 )   Chinese Summary
    Human faces have two important characteristics: (1) They are similar objects and the specific variations of each face are similar to each other; (2) They are nearly bilateral symmetric. Exploiting the two important properties, we build a unified model in identity subspace (UMIS) as a novel technique for face recognition from only one example image per person. An identity subspace spanned by bilateral symmetric bases, which compactly encodes identity information, is presented. The unified model, trained on an obtained training set with multiple samples per class from a known people group A, can be generalized well to facial images of unknown individuals, and can be used to recognize facial images from an unknown people group B with only one sample per subject. Extensive experimental results on two public databases (the Yale database and the Bern database) and our own database (the ICT-JDL database) demonstrate that the UMIS approach is significantly effective and robust for face recognition.
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    Gradient-Based Approach for Fine Registration of Panorama Images
    Hui Chen
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(13561KB) ( 1501 )   Chinese Summary
    This paper studies the application of gradient-based motion detection techniques (I.e., optical flow methods) for registration of adjacent images taken using a hand-held camera for the purposes of building a panorama. A general 8-parameter model or a more compact 3-parameter model is commonly used for transformation estimation. However, both models are approximations to the real situation when viewpoint position is not absolutely fixed but includes a small translation, and thus distortion and blurring are sometimes present in the final registration results. This paper proposes a new 5-parameter model that shows better result and has less strict requirement on good choice of unknown initial parameters. An analysis of disparity recovery range and its enlargement using Gaussian filter is also given.
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    Image Magnification Method Using Joint Diffusion
    Zhong-Xuan Liu, Hong-Jian Wang, and Si-Long Peng
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(1097KB) ( 1901 )   Chinese Summary
    In this paper a new algorithm for image magnification is presented. Because linear magnification/interpolation techniques diminish the contrast and produce sawtooth effects, in recent years, many nonlinear interpolation methods, especially nonlinear diffusion based approaches, have been proposed to solve these problems. Two recently proposed techniques for interpolation by diffusion, forward and backward diffusion (FAB) and level-set reconstruction (LSR), cannot enhance the contrast and smooth edges simultaneously. In this article, a novel Partial Differential Equations (PDE) based approach is presented. The contributions of the paper include: firstly, a unified form of diffusion joining FAB and LSR is constructed to have all of their virtues; secondly, to eliminate artifacts of the joint diffusion, soft constraint takes the place of hard constraint presented by LSR; thirdly, the determination of joint coefficients, criterion for stopping time and color image processing are also discussed. The results demonstrate that the method is visually and quantitatively better than Bicubic, FAB and LSR.
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    Leakage Current Estimation of CMOS Circuit with Stack Effect
    Yong-Jun Xu, Zu-Ying Luo, Xiao-Wei Li, Li-Jian Li, and Xian-Long Hong
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(510KB) ( 7426 )   Chinese Summary
    Leakage current of CMOS circuit increases dramatically with the technology scaling down and has become a critical issue of high performance system. Subthreshold, gate and reverse biased junction band-to-band tunneling (BTBT) leakages are considered three main determinants of total leakage current. Up to now, how to accurately estimate leakage current of large-scale circuits within endurable time remains unsolved, even though accurate leakage models have been widely discussed. In this paper, the authors first dip into the stack effect of CMOS technology and propose a new simple gate-level leakage current model. Then, a table-lookup based total leakage current simulator is built up according to the model. To validate the simulator, accurate leakage current is simulated at circuit level using popular simulator HSPICE for comparison. Some further studies such as maximum leakage current estimation, minimum leakage current generation and a high-level average leakage current macromodel are introduced in detail. Experiments on ISCAS85 and ISCAS89 benchmarks demonstrate that the two proposed leakage current estimation methods are very accurate and efficient.
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    Automatic Circuit Extractor for HDL Description Using Program Slicing
    Tun Li, Yang Guo, and Si-Kun Li
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(680KB) ( 1488 )   Chinese Summary
    Design extraction and reduction have been extensively used in modern VLSI design process. The extracted and reduced design can be efficiently processed by various applications, such as formal verification, simulation, automatic test pattern generation (ATPG), etc. This paper presents a new circuit extraction method using program slicing technique, and develops an elegant theoretical basis based on program slicing for circuit extraction from Verilog description. The technique can obtain a chaining slice for given signals of interest. Compared with related researches, the main advantages of the method include that it is fine grain; it has no hardware description language (HDL) coding style limitation; it is precise and is capable of dealing with various Verilog constructions. The technique has been integrated with a commercial simulation environment and incorporated into a design process. The results of practical designs show the significant benefits of the approach.
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    HSM2: A New Heuristic State Minimization Algorithm for Finite State Machine
    Heng Hu, Hong-Xi Xue, and Ji-Nian Bian
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(246KB) ( 1732 )   Chinese Summary
    This paper proposes a heuristic state minimization algorithm (HSM2) for finite state machines (FSM). HSM2 focuses on the generation and adjustment of the closed cover. First an initial closed cover is generated by heuristically selecting proper maximal compatibles to satisfy all the covering and closure conditions, and then it is adjusted to be a minimal or near minimal closed cover by heuristically removing repeated states. Experimental results show that the algorithm is faster and obtains better or the same solutions compared with conventional methods.
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    MuscleBuilder: A Modeling Tool for Human Anatomy
    Amaury Aubel and Daniel Thalmann
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(455KB) ( 1697 )   Chinese Summary
    A traditional multi-layered approach is adopted to human body modeling and deformation. The model is split into three general anatomical structures: the skeleton, musculature and skin. It is shown that each of these layers is modeled and deformed by using fast, procedural, ad-hoc methods that can painlessly be reimplemented. The modeling approach is generic enough to handle muscles of varying shape, size and characteristics and does not break in extreme skeleton poses. It is also described that the integrated MuscleBuilder system whose main features are: I) easy and quick creation of muscle deformation models; ii) automatic deformation of an overlying skin. It is shown that visually realistic results can be obtained at interactive frame rates with very little input from the designer.
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    Geometric Signal Compression
    Kun Zhou, Hu-Jun Bao, Jiao-Ying Shi, and Qun-Sheng Peng
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(734KB) ( 1652 )   Chinese Summary
    Compression of mesh attributes becomes a challenging problem due to the great need for efficient storage and fast transmission. This paper presents a novel geometric signal compression framework for all mesh attributes, including position coordinates, normal, color, texture, etc. Within this framework, mesh attributes are regarded as geometric signals defined on mesh surfaces. A planar parameterization algorithm is first proposed to map 3D meshes to 2D parametric meshes. Geometric signals are then transformed into 2D signals, which are sampled into 2D regular signals using an adaptive sampling method. The JPEG2000 standard for still image compression is employed to effectively encode these regular signals into compact bit-streams with high rate/distortion ratios. Experimental results demonstrate the great application potentials of this framework.
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    Multiresolution Free Form Object Modeling with Point Sampled Geometry
    Yong-Jin Liu, Kai Tang, and Matthew Ming-Fai Yuen
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(1005KB) ( 1493 )   Chinese Summary
    In this paper an efficient framework for the creation of 3D digital content with point sampled geometry is proposed. A new hierarchy of shape representations with three levels is adopted in this framework. Based on this new hierarchical shape representation, the proposed framework offers concise integration of various volumetric- and surface-based modeling techniques, such as Boolean operation, offset, blending, free-form deformation, parameterization and texture mapping, and thus simplifies the complete modeling process. Previously to achieve the same goal, several separated algorithms had to be used independently with inconsistent volumetric and surface representations of the free-form object. Both graphics and industrial applications are presented to demonstrate the effectiveness and efficiency of the proposed framework.
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    Surface Detail Capturing for Realistic Facial Animation
    Pei-Hsuan Tu, I-Chen Lin, Jeng-Sheng Yeh, Rung-Huei Liang, and Ming Ouhyoung
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(619KB) ( 1138 )   Chinese Summary
    In this paper, a facial animation system is proposed for capturing both geometrical information and illumination changes of surface details, called expression details, from video clips simultaneously, and the captured data can be widely applied to different 2D face images and 3D face models. While tracking the geometric data, we record the expression details by ratio images. For 2D facial animation synthesis, these ratio images are used to generate dynamic textures. Because a ratio image is obtained via dividing colors of an expressive face by those of a neutral face, pixels with ratio value smaller than one are where a wrinkle or crease appears. Therefore, the gradients of the ratio value at each pixel in ratio images are regarded as changes of a face surface, and original normals on the surface can be adjusted according to these gradients. Based on this idea, we can convert the ratio images into a sequence of normal maps and then apply them to animated 3D model rendering. With the expression detail mapping, the resulted facial animations are more life-like and more expressive.
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    Anti-Aliased Rendering of Water Surface
    Xue-Ying Qin, Eihachiro Nakamae, Wei Hua, Yasuo Nagai, and Qun-Sheng Peng
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(477KB) ( 1485 )   Chinese Summary
    Water surface is one of the most important components of landscape scenes. When rendering spacious water surface such as that of the lakes and reservoirs, aliasing and/or moire artifacts frequently occur in the regions far from the viewpoint. This is because water surface consists of stochastic water waves which are usually modeled by periodic bump mapping. The incident rays on the water surface are actually scattered by the bumped waves, and the reflected rays at each sample point are distributed in a solid angle. To get rid of the artifacts of moire pattern, we estimate this solid angle of reflected rays and trace these rays. An image-based accelerating method is adopted so that the contribution of each reflected ray can be quickly obtained without elaborate intersection calculation. We also demonstrate anti-aliased shadows of sunlight and skylight on the water surface. Both the rendered images and animations show excellent effects on the water surface of a reservoir.
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    Layered Textures for Image-Based Rendering
    Wen-Cheng Wang, Kui-Yu Li, Xin Zheng, and En-Hua Wu
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(604KB) ( 1616 )   Chinese Summary
    An extension to texture mapping is given in this paper for improving the efficiency of image-based rendering. For a depth image with an orthogonal displacement at each pixel, it is decomposed by the displacement into a series of layered textures (LTs) with each one having the same displacement for all its texels. Meanwhile, some texels of the layered textures are interpolated for obtaining a continuous 3D approximation of the model represented in the depth image. Thus, the plane-to-plane texture mapping can be used to map these layered textures to produce novel views and the advantages can be obtained as follows: accelerating the rendering speed, supporting the 3D surface details and view motion parallax, and avoiding the expensive task of hole-filling in the rendering stage. Experimental results show the new method can produce high-quality images and run faster than many famous image-based rendering techniques.
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    Method of Direct Texture Synthesis on Arbitrary Surfaces
    Fu-Li Wu, Chun-Hui Mei, and Jiao-Ying Shi
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(512KB) ( 1582 )   Chinese Summary
    A direct texture synthesis method on arbitrary surfaces is proposed in this paper. The idea is to recursively map triangles on surface to texture space until the surface is completely mapped. First, the surface is simplified and a tangential vector field is created over the simplified mesh. Then, mapping process searches for the most optimal texture coordinates in texture sample for each triangle, and the textures of neighboring triangles are blended on the mesh. All synthesized texture triangles are compressed to an atlas. Finally, the simplified mesh is subdivided to approach the initial surface. The algorithm has several advantages over former methods: it synthesizes texture on surface without local parameterization; it does not need partitioning surface to patches; and it does not need a particular texture sample. The results demonstrate that the new algorithm is applicable to a wide variety of texture samples and any triangulated surfaces.
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    Parametric Tracking of Legs by Exploiting Intelligent Edge
    Chun-Hong Pan, Hong-Ping Yan, and Song-De Ma
    Journal of Computer Science and Technology, 2004, 19 (5): 0-0. 
    Abstract   PDF(483KB) ( 1516 )   Chinese Summary
    In this paper the idea of Intelligent Scissors is adopted for contour tracking in dynamic image sequence. Tracking contour of human can therefore be converted to tracking seed points in images by making use of the properties of the optimal path (Intelligent Edge). The main advantage of the approach is that it can handle correctly occlusions that occur frequently when human is moving. Non-Uniform Rational B-Spline (NURBS) is used to represent parametrically the contour that one wants to track. In order to track robustly the contour in images, similarity and compatibility measurements of the edge are computed as the weighting functions of optimal estimator. To reduce dramatically the computational load, an efficient method for extracting the region interested is proposed. Experiments show that the approach works robustly for sequences with frequent occlusions.
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         1860-4749(Online)
CN 11-2296/TP

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