Beijing Zhongke Fulong Computer Technology Co.

Haidian District, China

Beijing Zhongke Fulong Computer Technology Co.

Haidian District, China

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Liu Y.-J.,Tsinghua University | Zhang J.-B.,Tsinghua University | Hou J.-C.,Beijing Zhongke Fulong Computer Technology Co. | Ren J.-C.,Tsinghua University | Tang W.-Q.,Beijing Zhongke Fulong Computer Technology Co.
IEEE Transactions on Visualization and Computer Graphics | Year: 2013

The huge number of points scanned from pipeline plants make the plant reconstruction very difficult. Traditional cylinder detection methods cannot be applied directly due to the high computational complexity. In this paper, we explore the structural characteristics of point cloud in pipeline plants and define a structure feature. Based on the structure feature, we propose a hierarchical structure detection and decomposition method that reduces the difficult pipeline-plant reconstruction problem in R3 into a set of simple circle detection problems in R2. Experiments with industrial applications are presented, which demonstrate the efficiency of the proposed structure detection method. © 2013 IEEE.


Su Z.,Nanjing University of Science and Technology | Zhou L.,Nanjing University of Finance and Economics | Li W.,Nanjing University of Science and Technology | Dai Y.,Nanjing University of Science and Technology | And 2 more authors.
Computers and Graphics (Pergamon) | Year: 2013

Topology authentication for computer-aided plant design (CAPD) models features intrinsically complex topological relations. This study investigates a semi-fragile watermarking scheme for CAPD models represented by parametric solids, which offers a solution to the problem of topology authentication. We first analyze the geometrical and topological structures of CAPD models. Then, we propose an effective semi-fragile watermarking method for topology authentication, which is based on Laplacian coordinates and quantization index modulation (QIM), against several attacks. We compute the custom Laplacian coordinate vector for each marked connection point according to the topological relation among joint plant components. The topology-based watermark for each marked connection point is generated from selected attributes of its joint plant component. Watermarks are inserted into the coordinates of marked connection points by adjusting the lengths of their Laplacian coordinate vectors. Both experimental results and theoretical analysis demonstrate that our approach can not only detect and locate malicious topology attacks, such as component modification and joint ends modification, but is also robust against various non-malicious attacks, such as similarity transformations and level-of-detail (LOD). © 2013 Elsevier Ltd.


Su Z.,Nanjing University of Science and Technology | Li W.,Nanjing University of Science and Technology | Kong J.,Nanjing University of Science and Technology | Dai Y.,Nanjing University of Science and Technology | And 2 more authors.
CAD Computer Aided Design | Year: 2013

The Computer-Aided Plant Design (CAPD) model characterizes its peculiar complex topology among a tremendous number of plant components under complex constraints rather than just geometrical shapes. Lots of watermarking schemes for CAD models have been proposed for geometrical information protection or authentication. However, in the literature, none of them has mentioned the problem of topology authentication for CAPD models yet. In this paper, a semi-fragile watermarking algorithm for topology authentication of CAPD models is presented. We first discuss the problem of topology authentication of CAPD models. Then a subset of the model's connection points are selected as mark points, also called watermark carriers, according to the mark point selecting principle. We encode the topological relation among components into watermarks. Afterwards, the topology based watermarks are embedded in mark points to keep them in a predefined relationship with neighboring connection points so that any changes will ruin the relationship between marked connection points and neighboring connection points. To the best of our knowledge, our algorithm is the first semi-fragile and blind scheme that can authenticate and verify the topology of CAPD models. Experimental results show that our approach not only can detect and locate malicious topology attacks such as components modification and joint ends modification, but also is robust against various non-malicious attacks such as similarity transformations and simplification.© 2013 Elsevier Ltd. All rights reserved.

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