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研究生:江欣益
研究生(外文):Xin-Yi Jiang
論文名稱:建立表面材質之反射特性以輔助多重三次元掃描之合併
論文名稱(外文):Recovery of Reflectance Properties for Merging Multiple 3D Scans
指導教授:張鈞法
指導教授(外文):Chun-Fa Chang
學位類別:碩士
校院名稱:國立清華大學
系所名稱:資訊工程學系
學門:工程學門
學類:電資工程學類
論文種類:學術論文
論文出版年:2003
畢業學年度:91
語文別:中文
論文頁數:34
中文關鍵詞:三次元掃描反射特性
外文關鍵詞:3D ScansReflectance Property
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3D電腦圖學在近幾年來的應用非常廣泛,但是建立3D模型這個步驟非常耗費時間、人力,因此有人設法簡化建立模型的方法,其中利用相機及Laser Scanner製作模型可以說是既快速又方便的方式,但是這個方法有個嚴重的缺點,就是在在不同觀察角度所取得的模型,其相片之間往往存在著很大色差、斑點,因此消除這些色差、斑點就成了一個重要的研究議題。
在本文中,我們將會提出一個方法來還原一個3D模型的表面反射特性;我們使用3D laser scanner跟相機,從不同觀察角度取得這個model的3D幾何資訊跟材質的照片,利用這些資訊跟一個簡化的Reflectance Model,透過我們的方法來還原這個3D模型的反射特性,其中包括它的Ambient、Diffuse及Specular的參數,並且利用這組參數來還原每個模型的底色,然後我們可以把不同角度所取得的模型結合起來,得到一個色差比較小的合併結果;此外,我們也可以利用這些還原回來的反射特性,把這個模型套用在各種不同打光的條件之下,得到各種不同打光的結果。

3D computer graphics had been widely used, but the construction of 3D content is still time consuming. In recent years, a geometry and image-based rendering approach is proposed to represent 3D models. According to this approach, we can construct realistic 3D models fast and conveniently. But when we are acquiring the 3D models from different viewing directions, the unstable environmental and man-made conditions will result in heavy color inconsistency and other artifacts. Therefore, the elimination of color inconsistency and artifacts of the merged model became a very important issue today.
In this thesis, we propose a method to eliminate the artifacts. In our method, we use the geometry and texture image of a model to find its reflectance properties. Then we can recover the ambient, diffuse, and specular intensity respectively. And we can apply the recovered reflectance properties to relight in different lighting conditions and to merge several models acquired from different viewing directions.

Index
Index of Figures and Tables
Abstract(Chinese)
Abstract(English)
Chapter 1 Introduction
Chapter 2 Related Work
Chapter 3 Method
§ 3-1 Simplified Phong Model
§ 3-2 Reflectance Modeling
§ 3-3 3D Texture Blending
Chapter 4 Implementation and Results
§ 4-1 Reflectance Modeling
§ 4-2 3D Texture Blending
Chapter 5 Conclusion and Future Work
Acknowledgement
References

[Boivin01] S. Boivin and A. Gagalowicz. “Image-based rendering of diffuse, specular and glossy surfaces from a single image,” Computer Graphics (Proceedings of SIGGRAPH 2001), pages 107—116.
[Chou&Chen02] H.L. Chou and C.C. Chen. “Texture Extraction and Blending without Prior Knowledge of Lighting Conditions,” In proceedings of 2002 IEEE Pacific-Rim Conference on Multimedia (PCM 2002), pages 1049—1056.
[Curless96]B. Curless, and M. Levoy. “A volumetric method for building complex models from range images,” In Computer Graphics, SIGGRAPH 96 Proceedings, 303—312.
[Debevec96] P. E. Debevec, C. J. Taylor, and J. Malik. “Modeling and Rendering Architecture from Photographs: A Hybrid Geometry- and Image-Based Approach,” Proceedings of SIGGRAPH 96, pages 11—20, August 1996.
[Levoy00] M. Levoy et al. “The digital Michelangelo project: 3D scanning of large statues,” Computer Graphics (Proceedings of SIGGRAPH 2000), pages 131—144.
[Sato97] Yoichi Sato, Mark D. Wheeler, and Katsushi Ikeuchi. “Object shape and reflectance modeling from observation,” Computer Graphics (Proceedings of SIGGRAPH 97), pages 379—388. Addison Wesley, August 1997.
[Ward92] G. J. Ward, “Measuring and modeling anisotropic reflection,” Computer Graphics (Proceedings of SIGGRAPH 92), volume 26, pages 265—272. ACM Press, July 1992.
[Yu99] Y. Yu, P. Debevec, J. Malik, and T. Hawkins, “Inverse global illumination : Recovering reflectance models of real scenes from photographs,” Computer Graphics (Proceedings of SIGGRAPH 99), volume 19, pages 215—224. August 1999.

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