現在網路相機的價格越來越便宜，功能也越來越完備，故我們可用一般低解析度網路相機，搭配單槍投影機，運用電腦視覺與幾何轉換的技術，來建立一套更加方便之會議展示系統。

會議中，有時因投影機擺設位置造成投影出的影像有透視失真(keystone distortion)現象，使用者必須手動調整投影機位置或使用投影機的梯形校正鍵，若投影出的影像不是梯形樣子，投影機的梯形校正鍵就不適用，故我們運用電腦視覺，以網路相機為輔助裝置，校正透視失真。網路相機拍攝投影機投影出來的影像，如果相機發現影像有透視失真，便用幾何轉換將投影機的來源影像予以變形，使投影出來的影像為已知長寬比的矩形。除此之外，我們實作虛擬按鍵來讓使用者以雷射筆和電腦進行互動，虛擬按鍵為當相機偵測到雷射點座落在虛擬按鍵上，便給電腦對應於按下虛擬按鍵的動作。本論文由特徵點的對應求得來源影像與相機影像的對應矩陣，對應矩陣為投影影像校正之基礎，並且使用對應矩陣來幫助我們尋找雷射點的位置。

As the popularity of the digital Web-cam，these devices are more and more cheaper and powerful. We can apply computer vision techniques with camera and projector to build a more convenient presentation system.

In presentation, sometimes due to the position of projector, the images appear the perspective distortion (keystone distortion). The user should manually adjust the position of projector or use the keystone corrections of the projector. But when the distortion is not trapezium, the built-in keystone corrections are not suitable in this situation. We present a computer-vision based method that uses a Web-cam to calibrate the keystone distortion. The Web-cam takes the images that the projector projected on the wall. If the Web-cam observes keystone distortions of the projected images, we use a geometric transform that pre-warps the images in the projector frame, such that these images appears rectangle with known aspect ratio after being projected on the wall. Besides, we implement the virtual buttons that allow users to interact with the computer. The virtual buttons means that when the camera detect the laser point is on the virtual buttons, computer triggers the event as the virtual button being pushed. This paper uses point-matching pairs to obtain the homography between camera image frame and source image frame. The homography, that is the fundamental of calibrating perspective distortions also help us to search the position of the laser point.

中文摘要 i
ABSTRACT ii
目錄 iii
圖目錄 iv
表目錄 vi
第一章 簡介 1
第一節 序論 1
第二節 相關研究 2
第三節 系統流程 6
第二章 理論與原理 8
第一節 特徵點擷取 8
第二節 投影機-相機之對應矩陣(Homography) [6] 14
第三節 投影影像校正[6] 16
第四節 虛擬按鍵(Virtual Buttons) 23
第三章 方法與實驗 25
第一節 建立對應矩陣 25
第二節 投影影像校正 41
第三節 虛擬按鍵實作 58
第四章 結論 67
第一節 討論 67
第二節 結論 69
第五章 參考文獻 71
英文文獻 71
中文文獻 73

英文文獻:
[1] S. Seitz “Camera calibration” SIGGRAPH’99 course on 3D photography,
http://www.cs.cmu.edu/~seitz

[2] Z. Sun and C. Rayburn, “Camera calibration”, Internship with UNR & Ford Motor Company, June 2001
http://arti.vub.ac.be/~bartj/vision.html

[3] Z. Zhang. “A flexible new technique for camera calibration.” IEEE Transactions on Pattern Analysis and Machine Intelligence, 22(11), pp.1330-1334, 2000

[4] M. Sonka, V. Hlavac, R. Boyle, "Image Processing，Analysis and Computer Vision", Second Edition，PWS publishing, Chapter 9.2 Geometry for 3D vision, pp. 448-457

[5] R. Raskar and P. Beardsley, "A Self-Correcting Projector", IEEE Computer Society Conference on Computer Vision and Pattern Recognition, Vol. 2, pp. 504-508, December 2001

[6] R. Sukthankar, R. G. Stockton, M. D. Mullin, "Automatic Keystone Correction for camera-assisted Presentation interface", Proceedings of International Conference on Multimedia Interfaces, pp. 601-714, 2000

[7] M. Sonka, V. Hlavac, R. Boyle, “Image Processing，analysis and computer vision”, (Second Ed.), PWS publish, Region identification, pp. 232-234, 1999.

[8] R. C. Gonzalez, “Digital Image Processing”, (Second Ed.) Prentice Hall, Chapter 10, pp. 568-569

[9] D. Csetverikov, "Basic algorithms for Digital Image analysis: A course", Class Notes,
http://ssip2003.info.uvt.ro/lectures/chetverikov/corner_detection.pdf.

[10] B. Zitov´a, J. Flusser, J. Kautsky, G. Peters,“Feature point detection in multiframe images”, Proceedings of the Czech Pattern Recognition Workshop 2000, Perslak, Czech Republic, pp. 117-122, February 2000

[11] D. R. O. Jr and T. Nielsen, "Laser pointer Interaction", Proceedings of SIGCHI conference on Human Factors in Computing Systems, Seattle, Washington, United States, pp. 17-22, 2001

[12] R. Sukthankar, R. G. Stockon, M. D. Mullin, “Self-Calibration Camera-Assisted Presentation Interface”, Proceedings of international conference on control, Automation, Robotics and Vision, pp. 247-253, 2000.

[13] C. Kirstein and H. Muller, “Interaction with a Projection Screen Using a camera-tracked Laser-pointer”, Proceedings of the 1998 Conference on Multimedia Modeling, pp. 191, 1998.

[14] R. Sidharta and J. Hero, ”Laser Point Auditorium Interaction”, Laser Pointer Audience Interaction, Final Report.
http://www.vrac.iastate.edu/~heroje/574/

[15] J.Y. Oh and W. Stuerzlinger, ”Laser Pointers as Collaborative Pointing Devices”, Proc. Graphics Interface, pp. 141-150, May 2002.

[16] J. Denton and J. R. Beveridge, “Two Dimensional Projective Point Matching“, Fifth IEEE Southwest Symposium on Image Analysis and Interpretation, Santa Fe, New Mexico, pp. 0077, April 7-9 2002.

[17] C. Wren, A. Azarbayejani, T. Darrell and A. Pentland, “Pfinder： tracking of the Human body”, IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol. 19, no 7, pp. 780-785, July 1997.

[18] Zi Cai Li, Tien Dai Bui, Yuan Yan Tang and Ching Y. Suen, “Computer Transformation of Digital Images and patterns”, World Scientific Press, Singapore, New Jersey, London, Bi-Quadratic and Bi-Cubic models, pp. 61-69, 1989

[19] Zi Cai Li, Tien Dai Bui, Yuan Yan Tang and Ching Y. Suen, “Computer Transformation of Digital Images and patterns”, World Scientific, Singapore, New Jersey, London, Splitting-Shooting Methods, pp. 95-135, 1989

[20] Kevin J. Steven "Probability and statistics". Addison Wesley.

[21] Zi Cai Li, Tien Dai Bui, Yuan Yan Tang and Ching Y. Suen, “Computer Transformation of Digital Images and patterns” World Scientific, Singapore, New Jersey, London, Perspective transformations, pp. 87-94, 1989

[22] U. Stilla and E. Michaelsen, “Detection of vehicles in video sequences from airborne thermal imager”, International Society For Photogrammetry And Remote sensing (ISPRS) Commission III Symposium, Graz Austria, September 9-13 2002.

中文文獻:
[A] 鐘國亮，“影像處理與電腦視覺”，東華書局
[B] 陳治宇，”虛擬滑鼠:以視覺為基礎之手勢辨識”，碩士論文，2003
[C] 中村拓男著，張士新譯，”Delphi於繪圖與圖形處理上的實習應用”，第四章點陣圖，博碩文化
[D] 錢達智，"Delphi 學習筆記 win32 基礎篇"，第六章，??峯出版