| Project/Area Number |
12450398
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
船舶工学
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| Research Institution | The University of Tokyo |
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Principal Investigator |
MASUDA Hiroshi Research into Artifacts, Center for Engineering, The University of Tokyo, Assistant Professor, 人工物工学研究センター, 助教授 (40302757)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Iwao School of Engineering, The University of Tokyo, Research Assistant, 大学院・工学系研究所, 助手 (70010890)
SHIRAYAMA Susumu School of Engineering, The University of Tokyo, Assistant Professor, 大学院・工学系研究所, 助教授 (10322067)
YAMATO Hiroyuki Graduate School of Frontier Sciences, The University of Tokyo, Professor, 大学院・新領域創成科学研究科, 教授 (50220421)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥15,000,000 (Direct Cost: ¥15,000,000)
Fiscal Year 2001: ¥6,000,000 (Direct Cost: ¥6,000,000)
Fiscal Year 2000: ¥9,000,000 (Direct Cost: ¥9,000,000)
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| Keywords | geometric model / fairing / free-form surface / CAD / Geometry Compression / ship-hull desing / lines / Web3D / 高品質曲面 / 制御点再配置 / 曲面圧縮 / 形状圧縮 / 離散コサイン変換 |
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| Research Abstract |
The purposes of this research are the development of an automatic surface fairing method for 3D ship-hull design and the development of a surface compression method for exchanging 3D data. The results of them are described as follows :
1. Surface Fairing
Surfaces generated by conventional fairing methods often have unwanted features such as local perturbations and global waves. This research developed a new fairing method that avoids these features. The method consists of the following three steps. (1) Rearranging control points of lines-curves so that the weighted sum of their arc lengths and curvatures are equally distributed. (2) Rearranging control points along lines-curves by applying low-pass filters repeatedly. (3) For eliminating the local perturbations, an energy minimization technique for thin-plates is used by regarding each surface as a thin-plate. Our method was applied to examples of hull-form surfaces, and could effectively remove the both of global waves and local perturbations with limited changes of the shape.
2. Surface Compression
Surface compression is effective for storing and distributing 3D CAD data, but existing compression methods failed to maintain the smoothness at surface boundaries. In our method, a NURBS surface is encoded using its boundaries and additional data. At first, an interpolating surface is calculated using the boundary curves of the original surface. Then, the differences between the original surface and the interpolating one are calculated. Difference data are optionally used, and they are represented in two types : distances only, and distances and orientations. One type is selected according to the tolerances of each surface. Finally, the boundary curves and the difference data are compressed using the discrete cosine trans-form (DCT). The results show our method can easily control the trade-off between the compression ratio and accuracy, and achieve a good compression rates. (291 words)
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