Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/8748
標題: 多投影機自動拼貼系統
Auto-calibration multi-projectors system
作者: 黃冠鈞
Huang, Kuan-Chun
關鍵字: projector;投影機;image calibration;edge blending;homography;Webcam校正;影像柔邊;影像變形;影像拼貼
出版社: 電機工程學系所
引用: Reference [1] David A. Forsyth, Jean Ponce, “Computer Vision A modern Approach”, Prentice Hall, 2003. [2] Rafael C. Gonzalez, Richard E, Woods, Steven L. Eddins, “Digital Image Processing Using Matlab, 1st Edition”, Prentice Hall, 2004. [3] A. Majumder, Zhu He, H. Towles, G. Welch, “Achieving color uniformity across multi-projector displays”, Visualization Proceedings, pages 117-124, 2000. [4] Fang-Tien Chen, “Automatic color matching for tiled multiple projectors”, NCU-CSIE, Master''s Thesis, 2006 [5] Chao Li, Hai Lin, Jiaoying Shi, “A Survey of Multi-Projector Tiled Display Wall Construction”, Image and Graphics Proceedings, Third International Conference, pages 452-455, 2004. [6] A. Raij, M. Pollefeys, “Auto-calibration of multi-projector display walls”, Pattern Recognition Proceedings, the 17th International Conference , vol. 1, pages 14-17, 2004 [7] B. Sajadi, M. Lazarov, M. Gopi, A. Majumder, “Color Seamlessness in Multi-Projector Displays Using Constrained Gamut Morphing”, Visualization and Computer Graphics, IEEE Transactions, vol. 15, Issue 6, pages 1317-1326, 2009. [8] Richard I. Hartley, “In Defense of the Eight-Point Algorithm”, Pattern Analysis and Machine Intelligence, IEEE Transactions, vol. 19, Issue 6, pages 580-593, 1997. [9] Heckbert, Paul S., “Fundmentals of Texture Mapping and Image Warping”, Technical Report Identifier: CSD-89-516, June 17, 1989. [10] Wun-Yi Lee, “Low-Cost Smart Projector for Home Entertainment”, MCU-CCE Master''s Thesis, 2007. [11] Ezekiel S., Bhasker, Pinaki Sinha, Aditi Majumder, “Asynchronous Distributed Calibration for Scalable and Reconfigurable Multi-Projector Displays”, Visualization And Computer Graphics, IEEE Transactions, vol. 12, Issue 5, pages 1101-1108, 2006. [12] Schikore D.R., Fischer R.A., Frank R., Gaunt R., Hobson J., Whitlock B., “High-resolution multiprojector display walls”, Computer Graphics and Applications, IEEE Transactions, vol. 20, Issue 4, pages 38-44, 2000. [13] Raskar R., Brown M.S. , Ruigang Yang, Wei-Chao Chen, Welch G., Towles H., Scales B., Fuchs H., “Multi-projector displays using camera-based registration”, Visualization ''99. Proceedings, pages 161-522, 2009. [14] Ezekiel Bhasker, Ray Juang, Aditi Majumder, “Registration Techniques for Using Imperfect and Partially Calibrated Devices in Planar Multi-Projector Displays”, Visualization and Computer Graphics, IEEE Transactions, vol. 13, Issue 6, pages 1352-1359, 2007. [15] Han Chen, Sukthankar R., Wallace G., Kai Li, “Scalable Alignment of Large-Format Multi-Projector Displays Using Camera Homography Trees”, Visualization, 2002. VIS 2002. IEEE vol. 13, Issue 6, pages 339-346, 2002. [16] Paul Bourke, “Edge blending using commodity projectors”, http://local.wasp.uwa.edu.au/~pbourke/texture_colour/edgeblend/, 2004.
摘要: 
隨著投影機的生產製造技術的蓬勃發展,相關的投影機應用也開始如雨後春筍般不斷湧現。靠著投影的光學特性,投影機不僅能做到平面顯示器大部份的應用,還能透過適當的影像處理來創造額外的視覺效果,如電影劇院、3D投影、環場影像投影、投影表演秀以及投影建構虛擬實境等,在在都是一般平面顯示器難以做到的應用,也因此奠定了投影機在這一方面需求上難以撼動的地位。然而,在這一方面的應用往往必須仰賴大尺寸高亮度高解析的投影機才能達成。因此,多投影機系統的相關研究也逐漸開始受到重視。
本文將在第一章首先探討目前現有的多投影機系統,有些是透過調整投影機擺放方式,使投影畫面邊緣剛好接合;有些則是透過高解析攝影機,來回授各投影機的擺設情況。然而這兩種常見的方式,都有其好處與缺點,因此本文針對這部分,提出了一個多投影機自動拼貼系統與其架構。
由於多投影機在拼貼時,往往除了會因各投影畫面間有所重疊而形成重疊區亮度較非重疊區處來得亮,還有可能因投影機擺設不當而造成投影畫面扭曲。因此在決定了系統架構後,為使最後的合成影像能夠看來平順連續,本文將在第二章簡介能夠調和重疊區影像亮度的影像柔邊技術,以及用來修正投影畫面扭曲的投影轉換矩陣。
在對於這兩項技術有初步的了解後,第三章首先提出多投影機自動拼貼系統的系統流程,並將深入探討第二章所提到的相關原理與技術。原始的影像柔邊技術直接套用到投影重疊區中,往往反而會使其影像亮度過低,而本文在此利用webcam做為回授,觀察投影機間特性,建立修正的影像柔邊權重表。再同樣透過webcam觀察各投影畫面扭曲情況,搭配適當修改的投影轉換矩陣,預先修正輸入影像。接著為進一步提高拼貼準確性,本文在此以投影測試圖樣的方式,不僅能提高影像解析程度,並能避免使用webcam影像中不理想的部分。
本文將在第四章中進行多個實驗以驗證第三章所提出的各項技術。首先以單投影機修正實驗確保透過webcam所獲得的投影轉換矩陣能夠正確地修正畫面扭曲;接著以webcam觀察投影機間特性,來建立正確的影像柔邊權重表,並透過實際測試來驗證;再來則將前兩項實驗結果套用在2×2的多投影機,並驗證修正後的結果是否符合預期;最後,為使得系統更容易擺設,本文將透過webcam校正實驗先針對其擺設所造成的拍攝影像扭曲做修正。第五章則針對各項實驗結果,提出能更進一步提升影像品質的方法。
預計本文的研究成果將能以更低成本的方式實現易於安裝且操作簡單的多投影機自動拼貼系統,進而更進一步提升投影機的應用。

The correlative applications are proposed increasingly with the improved technique of projector manufacture. The projectors can not only provide functions of flat panel display, but also create special visual effect, for instances movie theaters, 3D projection, surrounding display, projection performance, and visual reality, which are hardly implemented by flat panel displays. However, this kind of applications depends on high-level projectors. Gradually, the researches about multi-projectors system are taken seriously therefore.
First, the conventional multi-projectors system are discussed in the chapter one of this study, some of them makes the projections side by side through regulating the placements of projectors; others feedback the position of projectors by using a high-resolution camera. However, these two common methods have their own advantages and defects. Hence, an Auto-Calibration Multi-projectors System aimed to the situation above is provided in this paper.
When combining the projections of multi-projectors, brighter regions are usually appearing due to the overlaps of projections, and the projections are distorted by the keystone effect because of improper projector placements. Consequently, after building the system structure, to ensure the final combined projection is smooth and continuous for vision, the edge blending technique for removing the brighter regions and homography matrix in order to calibrate the distortion of projection are introduced in the chapter two.
After simply understanding the two techniques, the chapter three first proposes the system flow of the Auto-Calibration Multi-projectors System and deeply expatiates on the principles and theories mentioned in chapter two. Nevertheless, the brighter region turns into darker contrarily if the original edge blending technique is applied directly to the projection overlap. Therefore, a webcam is used to observe the properties between projectors and build a corrected edge blending weighting table. On the other hand, the pre-calibrated images are obtained by utilizing modified homography matrix according to distortion of each projector fedback from the webcam. To further improve the accuracy of projection combination, a projection test pattern is adopted to enhance the relative resolution and avoid using the unideal part of webcam image.
The chapter four provides experiments to prove the techniques mentioned in chapter three. The first experiment is single projection calibration which makes sure the homography matrix obtained from webcam calibrates the projection correctly; next, edge blending weighting tables are built from the properties between projectors, and then put the tables into test; the third experiment applies the result of the former two to 22 multi-projectors and checks the exactitude of outcomes; finally, in order to improve the convenience of the system, webcam calibration is proposed and calibrates the distortion due to improper webcam placement. The chapter five concludes each experiment and proffers solutions.
Expect the achievements of this paper can implement a low-cost and simple Auto-Calibration Multi-Projectors System to advance the practicability of projectors
URI: http://hdl.handle.net/11455/8748
其他識別: U0005-0208201001281700
Appears in Collections:電機工程學系所

Show full item record
 

Google ScholarTM

Check


Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.