面向RPM的点云数据直接分层处理技术及其软件实现
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摘要
本文研究了反求工程与快速原型制造集成中的关键问题，即如何从点云数据生成层片轮廓数据。目前主要有两种方法：一是建立点云数据的CAD模型，并对该模型三角剖分为STL文件，从STL文件中生成切片数据；二是直接将点云数据离散成STL文件，以生成切片。但是这两大类方法都存在消耗时间长、人工交互多等缺陷。
为了克服上述方法的不足，提出了一种新的方法，即点云数据的直接分层技术，主要包括数据预处理、点云数据直接分层方法、轮廓追踪与拟合三方面内容。
本文首先阐述了点云数据的预处理方法，包括选择分层位向、建立拓扑关系、法向补偿及平滑处理等操作；其次研究了直接分层的两种方法，即平行平面序列分层法和自由曲线法平面序列分层法，二者的基本原理相同，都是根据最小距离点对的连线与分层面截交求得切片数据；最后介绍了轮廓数据的处理，包括体元轮廓的追踪和轮廓线的提取，以及用双圆弧对轮廓线进行拟合等。
This paper studies how to generate the slice data from point clouds, which is the critical problem in the integration of Reverse Engineering and Rapid Prototyping Manufacturing. At present, there are two ways available. In the first
path, a CAD model is created first from point clouds then converted to a STL file. The STL file is then sliced to generate a series of layers for RP fabrication. The second path is to create the STL file directly from point clouds. However, there are drawbacks in these methods, such as long tune consumed, much manual interaction and so on.
A new method is brought forward to solve this question. It goes directly from point clouds to a RP slice file. Three problems, the preprocess of point clouds, the method of directly slicing the point clouds, the extraction and fit of contour data, are discussed.
This paper first expatiates the preprocess of data, which includes choosing the orientation to slice, topologizing the data, offsetting in the normal direction and smoothing the data. Secondly, it studies two ways of directly slicing, which is to generate the contour data on a series of parallel planes, or normal planes of a freeform curve. These two methods have the same principle, which gets the contour data by crossing the plane and the line between the two points of least distance. Finally, it addresses the process of contour data, such as extracting a cell-contour, sorting the points in one cell-contour to a contour line, and fitting the contour to a smooth one with biarc curves.
为了克服上述方法的不足，提出了一种新的方法，即点云数据的直接分层技术，主要包括数据预处理、点云数据直接分层方法、轮廓追踪与拟合三方面内容。
本文首先阐述了点云数据的预处理方法，包括选择分层位向、建立拓扑关系、法向补偿及平滑处理等操作；其次研究了直接分层的两种方法，即平行平面序列分层法和自由曲线法平面序列分层法，二者的基本原理相同，都是根据最小距离点对的连线与分层面截交求得切片数据；最后介绍了轮廓数据的处理，包括体元轮廓的追踪和轮廓线的提取，以及用双圆弧对轮廓线进行拟合等。
This paper studies how to generate the slice data from point clouds, which is the critical problem in the integration of Reverse Engineering and Rapid Prototyping Manufacturing. At present, there are two ways available. In the first
path, a CAD model is created first from point clouds then converted to a STL file. The STL file is then sliced to generate a series of layers for RP fabrication. The second path is to create the STL file directly from point clouds. However, there are drawbacks in these methods, such as long tune consumed, much manual interaction and so on.
A new method is brought forward to solve this question. It goes directly from point clouds to a RP slice file. Three problems, the preprocess of point clouds, the method of directly slicing the point clouds, the extraction and fit of contour data, are discussed.
This paper first expatiates the preprocess of data, which includes choosing the orientation to slice, topologizing the data, offsetting in the normal direction and smoothing the data. Secondly, it studies two ways of directly slicing, which is to generate the contour data on a series of parallel planes, or normal planes of a freeform curve. These two methods have the same principle, which gets the contour data by crossing the plane and the line between the two points of least distance. Finally, it addresses the process of contour data, such as extracting a cell-contour, sorting the points in one cell-contour to a contour line, and fitting the contour to a smooth one with biarc curves.
引文
1． 苏海，汪林祥等．反求工程中几种自由曲面重构方法的分析．昆明理工大学学报， 2001． 8，Vol．26 No.4：81-84
2． K. H. Lee, H. Woo. Direct integration of reverse engineering and rapid prototyping. Computers & Industrial Engineering, 2000, Vol.38: 21-38
3． 周儒荣．逆向工程与快速原型制造．计算机辅助设计与制造，2000． 9：6-9
4． Fujimoto M, Kariya K. An improved method for digitized data reduction for computer integrated manufacturing. Proceedings of the 1992 International Conference on Industrial Electronics, Control, Instrumentation, and Automation. 1992:896-901．
5． Veron P, Leon JC. Static polyhedron simplification using error measurements. Computer Aided Design,1997, Vol.29 No. 2:87-98
6． Chen YH, Ng CT, Wang YZ. Data reduction in integrated reverse engineering and rapid prototyping. International Journal of Computer Integrated Manufacturing, 1999, Vol. 12 No. 2:97-103
7． Hamann B. A data reduction scheme for triangulation surface. Computer Aided Geometric Desigh, 1994, Vol.11:197-214
8． Martin RR, Stroud IA, Marshall AD, Data reduction for reverse engineering. Computers in industry, 1998, Vol.40 No. 4:56-68
9． K. H. Lee, H. Woo. Point data reduction using 3D grids. International Journal of Advanced Manufacturing Technology, 2001, Vol. 18 No. 3:201-210
10． Hosni Y, Ferreira L, Burjanroppa R. Rapid prototyping through reverse engineering. Second Industrial Engineering Research Conference Proceedings, 1991．
11． Schoene C, Hoffmann J. Reverse engineering based on multi-axis digitized data. International Conference on Manufacturing Automation (ICMA' 97) , 1997, 909-923
12． Anne L. Marsan, Seth Allen, Prashant Kulkarni, Deba Dutta, Solid Freeform Fabrication Proceedings ,1997,661-668
13． Vail N K, WilkeW. Interfacing reverse engineering data to rapid prototyping. Solid freeform fabrication symposium, 1996,481-490
14． A Fisher. Multi-level models for reverse engineering and rapid prototyping in remote CAD systems. Computer Aided Design, 2000, Vol.32 No. 1: 27-38
15． Y. H. Chen, C. T. Ng. Integrated reverse engineering and rapid prototyping. Computers & Industrial Engineering, 1997． 12, Vol.33 No. 3-4: 481-484
16． Yan X, Gu P. A review of rapid prototyping technology and systems. Computer Aided Design, 1996, Vol.28: 307-318
17． Jamieson R, Hacker H. Direct slicing of CAD models for rapid prototyping. Rapid Prototyping Journal, 1995,Vol. 1 No. 2: 4-12
18． Stephen J Rock, Michael J wozny. Generating topological information from a "buckets of facets" . Solid Freeform Fabrication Symposium, 1996, 251-259
19． Gan G K Jacob, Chua chee Kai. Development of a new rapid prototyping interface. Computers in Industry, 1999, Vol.39 No. 1: 61-70
20． I Stroud. STL and extensions. Advances in Engineering software, 2000, Vol.31 No. 1:83-95
21． Zhiwen Zhao, Luc Laperriere. Adaptive direct slicing of the solid model for rapid prototyping. Proceedings of the first international conference on RP&M'98, Beijing, 272-278
22． Terry K K Chang, Mathew M F. Direct slicing of surface model for RP of thin-wall objects. Proceedings of the 1st International Conference on RP&M'98, Beijing, 612-617
23． Guduri S, Crawford R. H., Beaman J. J. Direct generation of contour files from constructive solid geometry representations. Solid freeform fabrication Proceedings, 1993
24． Vuyyuru P, Kirschman C, Fadel G M. A nurbs based approach for rapid prototyping realization. Fifth International Conference on Rapid Prototyping, Dayon, 229-240
25． Paul Alexander, Seth Allen, Debasish Dutta. Part orientation and build cost determination in layered manufacturing. Computer Aided Design, 1998． 4, Vol.30 No. 5: 343-356
26． 罗笑南，王若梅．计算机图形学．第二版．中山大学出版社：1999，215-241
27． 汤幼宁，魏生民，杨海成．基于Dexel模型的NC加工仿真和验证研究．西北：工业 大学学报，1997． 11，Vol．15 No．4：629-633
28．李江雄，柯映林．基于特征的复杂曲面反求建模技术研究．机械工程学报，2000．5，Vol．36 No．5：18-22
29．杨继新．三维服装CAD几何学原理与数字化立体裁剪技术基础的研究．大连理工大学博士论文，2001．2，107-109
30．施法中，计算机辅助几何设计与非均匀有理B样条．第一版．北京航空航天大学出版社：1994，45-49，228-317
31．彭学军，肖跃加，韩明，黄树槐．快速原型制造系统中切片数据拟合算法的研究．华中理工大学学报，2000．5，Vol．28 No．5：27-29
32．Bahattin Koc, Yawei Ma, Yuan-Shin Lee. Smoothing STL files by Max-Fit biarc curces for rapid prototyping. Rapid Prototyping Journal, 2000, Vol. 6 No.3:186-203
33．江开勇，刘道远．快速成型制造实体分层软件设计．华侨大学学报(自然科学版)，1998．1，Vol．19 No．1：65-69
2． K. H. Lee, H. Woo. Direct integration of reverse engineering and rapid prototyping. Computers & Industrial Engineering, 2000, Vol.38: 21-38
3． 周儒荣．逆向工程与快速原型制造．计算机辅助设计与制造，2000． 9：6-9
4． Fujimoto M, Kariya K. An improved method for digitized data reduction for computer integrated manufacturing. Proceedings of the 1992 International Conference on Industrial Electronics, Control, Instrumentation, and Automation. 1992:896-901．
5． Veron P, Leon JC. Static polyhedron simplification using error measurements. Computer Aided Design,1997, Vol.29 No. 2:87-98
6． Chen YH, Ng CT, Wang YZ. Data reduction in integrated reverse engineering and rapid prototyping. International Journal of Computer Integrated Manufacturing, 1999, Vol. 12 No. 2:97-103
7． Hamann B. A data reduction scheme for triangulation surface. Computer Aided Geometric Desigh, 1994, Vol.11:197-214
8． Martin RR, Stroud IA, Marshall AD, Data reduction for reverse engineering. Computers in industry, 1998, Vol.40 No. 4:56-68
9． K. H. Lee, H. Woo. Point data reduction using 3D grids. International Journal of Advanced Manufacturing Technology, 2001, Vol. 18 No. 3:201-210
10． Hosni Y, Ferreira L, Burjanroppa R. Rapid prototyping through reverse engineering. Second Industrial Engineering Research Conference Proceedings, 1991．
11． Schoene C, Hoffmann J. Reverse engineering based on multi-axis digitized data. International Conference on Manufacturing Automation (ICMA' 97) , 1997, 909-923
12． Anne L. Marsan, Seth Allen, Prashant Kulkarni, Deba Dutta, Solid Freeform Fabrication Proceedings ,1997,661-668
13． Vail N K, WilkeW. Interfacing reverse engineering data to rapid prototyping. Solid freeform fabrication symposium, 1996,481-490
14． A Fisher. Multi-level models for reverse engineering and rapid prototyping in remote CAD systems. Computer Aided Design, 2000, Vol.32 No. 1: 27-38
15． Y. H. Chen, C. T. Ng. Integrated reverse engineering and rapid prototyping. Computers & Industrial Engineering, 1997． 12, Vol.33 No. 3-4: 481-484
16． Yan X, Gu P. A review of rapid prototyping technology and systems. Computer Aided Design, 1996, Vol.28: 307-318
17． Jamieson R, Hacker H. Direct slicing of CAD models for rapid prototyping. Rapid Prototyping Journal, 1995,Vol. 1 No. 2: 4-12
18． Stephen J Rock, Michael J wozny. Generating topological information from a "buckets of facets" . Solid Freeform Fabrication Symposium, 1996, 251-259
19． Gan G K Jacob, Chua chee Kai. Development of a new rapid prototyping interface. Computers in Industry, 1999, Vol.39 No. 1: 61-70
20． I Stroud. STL and extensions. Advances in Engineering software, 2000, Vol.31 No. 1:83-95
21． Zhiwen Zhao, Luc Laperriere. Adaptive direct slicing of the solid model for rapid prototyping. Proceedings of the first international conference on RP&M'98, Beijing, 272-278
22． Terry K K Chang, Mathew M F. Direct slicing of surface model for RP of thin-wall objects. Proceedings of the 1st International Conference on RP&M'98, Beijing, 612-617
23． Guduri S, Crawford R. H., Beaman J. J. Direct generation of contour files from constructive solid geometry representations. Solid freeform fabrication Proceedings, 1993
24． Vuyyuru P, Kirschman C, Fadel G M. A nurbs based approach for rapid prototyping realization. Fifth International Conference on Rapid Prototyping, Dayon, 229-240
25． Paul Alexander, Seth Allen, Debasish Dutta. Part orientation and build cost determination in layered manufacturing. Computer Aided Design, 1998． 4, Vol.30 No. 5: 343-356
26． 罗笑南，王若梅．计算机图形学．第二版．中山大学出版社：1999，215-241
27． 汤幼宁，魏生民，杨海成．基于Dexel模型的NC加工仿真和验证研究．西北：工业 大学学报，1997． 11，Vol．15 No．4：629-633
28．李江雄，柯映林．基于特征的复杂曲面反求建模技术研究．机械工程学报，2000．5，Vol．36 No．5：18-22
29．杨继新．三维服装CAD几何学原理与数字化立体裁剪技术基础的研究．大连理工大学博士论文，2001．2，107-109
30．施法中，计算机辅助几何设计与非均匀有理B样条．第一版．北京航空航天大学出版社：1994，45-49，228-317
31．彭学军，肖跃加，韩明，黄树槐．快速原型制造系统中切片数据拟合算法的研究．华中理工大学学报，2000．5，Vol．28 No．5：27-29
32．Bahattin Koc, Yawei Ma, Yuan-Shin Lee. Smoothing STL files by Max-Fit biarc curces for rapid prototyping. Rapid Prototyping Journal, 2000, Vol. 6 No.3:186-203
33．江开勇，刘道远．快速成型制造实体分层软件设计．华侨大学学报(自然科学版)，1998．1，Vol．19 No．1：65-69