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Su Z.,Nanjing University of Science and Technology | Li W.,Nanjing University of Science and Technology | Dai Y.,Nanjing University of Science and Technology | Tang W.,CAS Institute of Computing Technology | Tang W.,Beijing Zhongke Fulong Computers Technology Co.
Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao/Journal of Computer-Aided Design and Computer Graphics | Year: 2011

This paper presents a novel and robust blind watermarking algorithm for 3D parametric process plant models based on an improved logistic chaotic system. Instead of modifying the CAD model's geometry or topology information, which is mostly used by existing algorithms, our approach embeds the watermarks into the model's dual points by making full use of the model's topology information. Group operation of dual points is processed based on the improved logistic chaotic system, and the same information is embedded into the points of the same group by slightly modifying the point's size. The watermarks can be blindly extracted according to the relationship between the sizes of each pair of dual points. Theoretical analysis and experimental results show that the algorithm can resist many attacks such as cropping, adding, scaling and mesh simplification without modifying the model's geometry and topology information. Source


Su Z.,CAS Institute of Computing Technology | Su Z.,University of Chinese Academy of Sciences | Tang W.,CAS Institute of Computing Technology | Tang W.,Beijing Zhongke Fulong Computers Technology Co. | And 3 more authors.
Jisuanji Fuzhu Sheji Yu Tuxingxue Xuebao/Journal of Computer-Aided Design and Computer Graphics | Year: 2010

The performance of current network-based remote rendering systems relies on the bandwidth and latency of the network during visualization. In order to gain high frame rates, they need time consuming preprocessing and additional storage. Design review has practical requirements on the preprocessing time, frame rates and visual fidelity. In this paper, a network-based interactive out-of-core rendering system for large-scale process plant models was proposed. First, the model's geometry parameters and topology information are transmitted from the server before visualization. Then the model's out-of-core representation is organized and computed locally according to the model feature. By analyzing the content and motion characteristic of the reviewer, a novel visibility-based pre-fetching technique is presented. It takes into account the reviewer's motion characteristic. No triangles are transmitted during visualization. The algorithm can be implemented on a general PC over the network. It can preprocess a 21-million-triangles model within 5 minutes and achieve 30 fps smooth frame rates on average without sacrificing the image quality. Experimental results show that the rendering performance doesn't depend on the network's bandwidth and latency. Source


Zhou J.,Nanjing University of Science and Technology | Tang W.,Nanjing University of Science and Technology | Tang W.,CAS Institute of Computing Technology | Tang W.,Beijing Zhongke Fulong Computers Technology Co. | And 3 more authors.
Journal of Computational Information Systems | Year: 2011

In order to solve the contradictions between the heterogeneous information with large quantities, various categories and the computers with limited performance in three-dimensional review, an information model combined scene tree and attribute tree is proposed. This model could organize the information from different CAD systems with a unified structure, also could optimize the query speed of information. Based on this model, a three-dimensional review system is implemented and the key technologies of this system, such as information storage technology, information export technology, model reconstruction technology and information inquiry technology, are proposed. Examples show that the three-dimensional review system could work on a general PC to review large quantity of design information from different majors, and ensure real-time interaction at the same time. Copyright © 2011 Binary Information Press. Source

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