在大型展覽活動場合常會看到多投影機拼接投影的應用，但一般的多投影拼接系統均需透過人工的方式來安裝和校正，在投影機數量很大的情況下，這種方式非常耗費人力時間，而且不具環境的適應性。本論文提出一個以攝影機為基礎的自動化建置多投影機拼接系統的方法，基於此一方法，我們設計並實作出一個嵌入式多投影機拼接系統。此一系統採用主從(master/slave)架構，master和slave的控制器皆以ARM Cortex-A8嵌入式處理器為核心，master控制器藉由攝影機取得多台投影機的投影資訊，進行個別投影機的幾何校正與兩台投影機的重疊區域亮度校正，slave控制器則負責每一台投影機的顯示控制。進而實現一個無接縫的多投影機自動拼接系統。實驗顯示，我們的系統具有良好的投影拼接品質和傑出的同步機制。

The application of multi-projector is often seen in a large exhibition. In general, multi-projector display system should be manually installed and calibrated by human. It is time-consuming and non-adaptable for the environment variation.
We proposed a camera-based automatic multi-projector stitching method and implemented it into an embedded multi-projector display system. The system is consisted by a master controller and two or multiple slave controllers. The master controller captures the display images from all the projectors by camera and executes the geometric calibration and the brightness calibration for the overlap projection region between two projectors. The slave controllers serve for the display control of individual projector. Finally, a seamless multi-projector automatic stitching system is realized. Experiments show that our embedded multi-projector display system has good stitching quality as well as excellent synchronization mechanism.

[1] (2000). PowerWall. Available: http://www.fakespace.com
[2] G. Humphreys, M. Eldridge, I. Buck, G. Stoll, M. Everett, and P. Hanrahan, "WireGL: A Scalable Graphics System for Clusters," presented at the SIGGRAPH '01 Proceedings of the 28th annual conference on Computer graphics and interactive techniques, ACM New York, NY, USA, 2001.
[3] K. Li, H. Chen, Y. Chen, D. W.Clark, P. Cook, S. Damianakis, G. Essl, A. Finkelstein, T. Funkhouser, T. Housel, A. Klein, Z. Liu, E. Praun, RudrajitSamanta, B. Shedd, J. P. Singh, G. Tzanetakis, and J. Zheng, "Early Experiences and Challenges in Building and Using A Scalable Display Wall System," Computer Graphics and Applications, vol. 20, pp. 29-37, Jul/Aug 2000 2000.
[4] C. Cruz-Neira, D. J. Sandin, and T. A. DeFanti, "Surround-Screen Projection-Based Virtual Reality:The Design and Implementation of the CAVE," presented at the SIGGRAPH '93 Proceedings of the 20th annual conference on Computer graphics and interactive techniques, ACM New York, NY, USA, 1993.
[5] K. Li, H. Chen, Y. Chen, D. W. Clark, P. Cook, S. Damianakis, G. Essl, A. Finkelstein, T. Funkhouser, Timothy, Housel, A. Klein, Z. Liu, E. Praun, R. Samanta, J. P. S. Ben Shedd, G. Tzanetakis, and J. Zheng, "Building and Using A Scalable Display Wall System," vol. 20, pp. 29 - 37, Jul/Aug 2000.
[6] Y. Chen, D. Clark, A. Finkelstein, T. Housel, and K. Li, "Automatic Alignment Of High-Resolution Multi-Projector Displays Using An Un-Calibrated Camera," in VISUALIZATION '00 Proceedings of the 11th IEEE Visualization 2000 Conference (VIS 2000), IEEE Computer Society Washington, DC, USA ©2000 2000.
[7] M. Brown, A. Majumder, and R. Yang, "Camera-Based Calibration Techniques for Seamless Multi-Projector Displays," IEEE Transactions on Visualization and Computer Graphics vol. 11, pp. 193-206 March 2005.
[8] R. Raskar, J. v. Baar, P. Beardsley, T. Willwacher, S. Rao, and C. Forlines, "iLamps: Geometrically Aware and Self-configuring Projectors," in SIGGRAPH '05 ACM SIGGRAPH 2005 Courses, ACM New York, NY, USA, 2005.
[9] A. Majumder and R. Stevens, "LAM: Luminance Attenuation Map for Photometric Uniformity in Projection Based Displays," in VRST '02 Proceedings of the ACM symposium on Virtual reality software and technology, ACM New York, NY, USA, 2002, pp. 147-154.
[10] C. Jaynes, B. Seales, K. Calvert, Z. Fei, and J. Griffioen, "The Metaverse - A Collection of Inexpensive, Self-configuring,Immersive Environments," 2003.
[11] R. Raskar, M. S. Brown, R. Yang, W. Chen, G. Welch, H. Towles, B. Seales, and H. Fuchs, "Multi-projector displays using camera-based registration," in Visualization '99. Proceedings, San Francisco, CA, USA, 1999, pp. 161 - 522.
[12] R. Raskar, G. Welch, M. Cutts, A. Lake, L. Stesin, and H. Fuchs, "The Office of the Future: A Unified Approach to Image-Based Modeling and Spatially Immersive Displays," in SIGGRAPH '98 Proceedings of the 25th annual conference on Computer graphics and interactive techniques, 1998, pp. 179-188.
[13] R. Yang, D. Gotz, J. Hensley, H. Towles, and M. Brown, "PixelFlex: A Reconfigurable Multi-Projector Display System," in Visualization, 2001. VIS '01. Proceedings, San Diego, CA, USA, 2001, pp. 167 - 554.
[14] S. K. Nayar, H. Peri, M. D. Grossberg, and P. N. Belhumeur, "A Projection System with Radiometric Compensation for Screen Imperfections," 2003.
[15] R.Surati, "Scalable Self-Calibrating Display Technology for Seamless Large-Scale Displays," 1999.
[16] TorsionSoft Tech. Available: http://www.edge-blending.com/index.htm
[17] Matrox. Available: http://www.matrox.com/graphics/en/
[18] H. Chen, R. Sukthankar, G. Wallace, and K. Li, "Scalable Alignment of Large-Format Multi-Projector Displays Using Camera Homography Trees," in Visualization, 2002. VIS 2002. IEEE, Boston, MA, USA, 2002, pp. 339-346.
[19] X. Wang and J. Wen, "Design of Video Players System for Multi-Projector Tiled Display Wall," in Image and Signal Processing (CISP), 2010 3rd International Congress on, Yantai, 2010.
[20] I. Garcia-Dorado and J. Cooperstock, "Fully automatic multi-projector calibration with an uncalibrated camera," presented at the Computer Vision and Pattern Recognition Workshops (CVPRW), 2011 IEEE Computer Society Conference on, Colorado Springs, CO, 2011.
[21] R. A. Chorley and J. Laylock, "Human Factor Consideration for the Interface between Electro-Optical Display and the Human Visual System," 1981.
[22] E. B. Goldstein, "Sensation and Perception," 2001.
[23] R. L. D. Valois and K. K. D. Valois, "Spatial Vision," 1990.
[24] A. Majumder and R. Stevens, "Color Nonuniformity in Projection-Based Displays: Analysis and Solutions," IEEE Transactions on Visualization and Computer Graphics, vol. 10, pp. 177-188 March 2004 2003.
[25] A. Majumder, Z. He, H. Towles, and GregWelch, "Achieving Color Uniformity Across Multi-Projector Displays," in Visualization 2000. Proceedings, Salt Lake City, UT, USA, 2000.
[26] G. Wallace, H. Chen, and K. Li, "Color Gamut Matching for Tiled DisplayWalls," in EGVE '03 Proceedings of the workshop on Virtual environments, New York, NY, USA, 2003, pp. 293-302
[27] L. Feng and X. Jing-Ming, "Algorithm of Edge Blending Based on the Nonlinear Function," in Intelligent Computing and Intelligent Systems, 2009. ICIS 2009. IEEE International Conference on, Shanghai, 2009, pp. 224 - 227.
[28] A. Majumder, "A Practical Framework to Achieve Perceptually Seamless Multi-Projector Displays," ed, 2003.
[29] H. Chang, X. Lei, and S. Dai, "Equalizer-based Parallel Rendering Framework for Multi-Projector Tiled Display System," presented at the System Simulation and Scientific Computing, 2008. ICSC 2008. Asia Simulation Conference - 7th International Conference on, Beijing, 2008.
[30] B. B. Gnecco, P. A. Bressan, R. d. D. Lopes, and M. K. Zuffo, "DICElib: a Real Time Synchronization Library for Multi-Projection Virtual Reality Distributed Environments."
[31] X. Wang and J. Wen, "Design of Video Players System for Multi-Projector Tiled Display Wall," presented at the Image and Signal Processing (CISP), 2010 3rd International Congress on, Yantai, 2010.
[32] B. Neal, P. Hunkin, and A. McGregor, "Distributed OpenGL Rendering in Network Bandwidth Constrained Environments," in EG PGV'11 Proceedings of the 11th Eurographics conference on Parallel Graphics and Visualization, Eurographics Association Aire-la-Ville, Switzerland, Switzerland, 2011, pp. Pages 21-29.
[33] M. P. GUIMARAES, P. A. BRESSAN, and M. K. ZUFFO, "Frame Lock Synchronization for Multiprojection Immersive Environments based on PC Graphics Clusters."
[34] NTP系統時間調整伺服器. Available: http://www.l-penguin.idv.tw/article/ntp-client.htm