臺灣博碩士論文加值系統

在計算機圖學領域裡，製作逼真的人臉模型及利用它們產生臉部表情動畫是一個熱門的研究領域，目前也還沒有一個好的解法。傳統上臉部塑形必須大費周章的以人力製作，並且在模型上加入特別的參數控制機制以便製作動畫。近年來，越來越多的研究開始使用三維掃描器來得到數位化的人臉模型，並且藉由人臉組織跟肌肉運動學特性的模擬，也得到了更真實的臉部表情動畫。然而，三維掃描器到目前為止，仍有一些實際應用上的缺點，需要以人工輔助修改模型，因此還需要一些改良的方法來建立適合合成臉部表情動畫的個人化模型。
在本論文中，我們提出一個基於解剖學結構的臉部模型建構及變形的方法，使之適合即時地合成臉部表情動畫。在我們的臉部模型裡，頭骨結構具有頭顱重建上常用的標記資料及其表皮厚度資料，表皮上也有相對應的標記資料，我們利用這些資料作模型上的變形，這讓表皮與骨頭的位置有解剖學上的依據。頭骨及表皮上具有肌肉在其上的位置資訊，因此我們可以快速並自動在臉部模型上建立肌肉。而表皮上的MPEG4特徵點用來變形使之近似掃瞄器得到的個人化臉部模型。所以在我們產生的個人化臉部模型中，都具備了內部頭骨資料及肌肉料，也就是說它們都有相同變形機制─肌肉，我們可以藉由控制肌肉收縮來合成臉部表情。
我們也進一步利用肌肉來達成臉部表情的重置與編輯，使得臉部表情動作資料的重複使用及產生新的動作資料可以更方便的達到。

Animating lifelike human facial expression is a challenging task in computer graphics. There are two major unsolved problems in it. One is how to construct lifelike human facial models and another is how to animate these models. Traditionally, facial models have been build painstakingly by manual digitization and animated by ad hoc parametrically controlled facial mesh deformations. More recently, the 3D scanner has been used to digitize facial models and they have achieved more realistic animation through the dynamic simulation of facial tissues and muscles. However, the facial models which from 3D scanning still required user assistance to construct individual facial models suitable for animating facial expression.
In this thesis, we present a construction and deformation method for head models with anatomical structure, suitable for real-time facial animation. Based on our facial modeling method, the skull is equipped with landmarks and skin thickness data of facial reconstruction and has the corresponding landmarks on skin, which allows us to deform the skull and skin in anthropometrically ways. We also have the muscle attachment points on skull and insertion points on skin, which allows us to automatically construct muscles. Finally, some feature points of MPEG4 on skin are used to deform our model to fit the individual facial model. On any deformed model, the underlying muscle and bone structure are adapted as well, such that the model is animatable using the same muscle contraction parameters.
We also use these muscles to achieve the expression retargeting and editing. Moreover, we show that the advantages of our algorithm are not only to reuse expression data but also to generate new expression data if muscle model is applied.

中文摘要
英文摘要 (Abstract)
致謝 (Acknowledgement)
目錄 (Contents)
圖形目錄 (Figures)
Chapter 1. 前言
1.1 研究動機
1.2 論文架構
Chapter 2. 相關成果介紹
2.1 虛擬人類 (Virtual human) 的相關標準
2.1.1 MPEG 4 -- SNHC (Synthetic/Natural Hybrid Coding)
2.1.2 H-ANIM (Humanoid Animation Working Group)
2.1.3 X3D (Extensible 3D Graphics)
2.1.4 HumanML (Human Markup Language)
2.1.5 FACS (Facial Action Coding System)
2.2 電腦臉部動畫的發展
2.2.1 臉部塑形 (Modeling faces)
2.2.2 電腦臉部動畫技巧 (Computer facial animation techniques)
Chapter 3. 基於肌肉之臉部表情合成法
3.1 臉部模型
3.1.1 解剖學
3.1.2 組成構造
3.1.3 中性臉部模型
3.1.4 個人化臉部模型
3.2 肌肉模型
3.2.1 線性肌函數
3.2.2 括約肌函數
3.3 臉部肌肉的建立
3.4 臉部表情的合成
3.4.1 表情資料的來源
3.4.2 表情資料的轉換
Chapter 4. 臉部表情之重置與編輯
4.1 表情的重置 (Expression Retargeting)
4.2 表情的編輯 (Expression Editing)
Chapter 5. 實驗結果與評量
Chapter 6. 結論與未來展望
參考文獻（Bibliography）

[1] Justine Cassell, Catherine Pelachaud, Norman Badler, Mark Steedman, Brett Achorn, Tripp Becket, Brett Douville, Scott Prevost, Matthew Stone. "ANIMATED CONVERSATION: Rule-based Generation of Facial Expression, Gesture & Spoken Intonation for Multiple Conversational Agents". Computer Graphics Proceedings, Annual Conference Series, 1994.
[2] P. Ekman and W. V. Friesen. “Manual for the Facial Action Coding System”. Consulting Psychologists Press, Inc., Palo Alto, CA, 1978.
[3] Marc Escher, Nadia Magnenat Thalmann. "Automatic 3D Cloning and Real-Time Animation of a Human Face". Computer Animation ''97, Geneva, Switzerland, 1997.
[4] H.D. Kochanek and R.H. Bartels. "Interpolating splines with local tension, continuity and bias control". Computer Graphics, 3(18):33-41, 1982.
[5] Yuencheng Lee, Demetri Terzopoulos, and Keith Waters. “Realistic Modeling for Facial Animation”. SIGGRAPH 95, 1995.
[6] N. Magnenat-Thalmann, N. E. Primeau, and D. Thalmann. “Abstract muscle actions procedures for human face animation”. Visual Computer, 3(5):290-297, 1988.
[7] F.I. Parke. "Parameterizes Models for Facial Animation". IEEE Computer Graphics and Applications, 2(9):61-68, November 1982.
[8] F.I. Parke. “Techniques for facial animation”. In N. Magnenat-Thalmann and D. Thalmann, editors, New Trends in Animation and Visualization, pages 229-241. John Wiley, Chichester, 1991.
[9] F.I. Parke, K. Waters. "Computer Facial Animation". A K Peters, 1996.
[10] Bartels, R. H., Beatty, J. C., and Barsky, B. A., An Introduction to Splines for Use in Computer Graphics and Geometric Modeling. Morgan Kaufmann Publishers, Inc., 1987.
[11] Demetri Terzopoulos, Keith Waters. "Physically-based Facial Modelling, Analysis, and Animation". Journal of Visualization and Computer Animation, 1(4):73-80, March 1990.
[12] Keith Waters. "A Muscle Model for Animating Three-dimensional facial expressions". Computer Graphics (SIGGRAPH ''87), 21(4):17-24, July 1987.
[13] Bruderlin, A and Williams, L. Motion Signal Processing. Proceedings SIGGRAPH ''95
[14] Popovic, Z and Witkin, A. Motion Warping. Proceedings SIGGRAPH ''95
[15] Pighin, J. Hecker, D. Lischinski, Szeliski R, and D. Salesin. Synthesizing realistic facial expressions from photographs. In Computer Graphics Proceedings SIGGRAPH’98, pages 75—84, 1998.
[16] V. Blanz and T. Vetter. A morphable model for the synthesis of 3D faces. In Computer Graphics Proceedings SIGGRAPH’99.
[17] Guenter, C. Grimm, D. Wolf, H. Malvar, and F. Pighin. Making faces. In Computer Graphics Proceedings SIGGRAPH’98, pages 55—66, 1998.
[18] M. Jones and T. Poggio. Multidimensional morphable models: A framework for representing and matching object classes. In Proceedings of the Sixth International Conference on Computer Vision, Bombay, India, 1998.
[19] D. DeCarlos, D. Metaxas, and M. Stone. An anthropometric face model using variational techniques. In Computer Graphics Proceedings SIGGRAPH’98, pages 67—74, 1998.
[20] Lance Williams, Performance-driven facial animation. Conference proceedings on Computer graphics, SIGGRAPH 90, Pages 235 - 242
[21] Mark J. L. Orr, Introduction to Radial Basis Function Networks, http://www.anc.ed.ac.uk/~mjo/rbf.html
[22] J. P. Lewis, Matt Cordner and Nickson Fong, Pose space deformation: a unified approach to shape interpolation and skeleton-driven deformation, Conference proceedings on Computer graphics, SIGGRAPH 2000, Pages 165 - 172
[23] Karan Singh and Eugene Fiume, Wires: a geometric deformation technique, Conference proceedings on Computer graphics, SIGGRAPH 98, Pages 405 — 414
[24] Thomas W Sederberg and Scott R Parry, Free-form deformation of solid geometric models, Conference proceedings on Computer graphics, SIGGRAPH 86, Pages 151 — 160
[25] SILVA, F., VELHO, L. and GOMES, J., Motion Reparametrization. In EUROGRAPHICS''98 Technical Note (short-papers proc.), pages 1.5.1-1.5.4, Lisbon, september 1998. Springer-Verlag
[26] Dierckx, P., Curve and Surface Fitting with Splines. Oxford University Press,New York, 1993.
[27] Michael Gleicher. Retargeting Motion to New Characters, Proceedings of SIGGRAPH 98,Computer Graphics Proceedings, Annual Conference Series, pp. 33-42 (July 1998, Orlando, Florida). Addison-Wesley. Edited by Michael Cohen.
[28] Witkin, A., and Popovic, Z., Motion Warping. In Computer Graphics (SIGGRAPH''95 Proceedings), 1995, pp. 105-108.
[29] O. Saligon, A. Le Mehaute, C. Roux, Facial Expression simulation with RBF, International Workshop on SNHC and 3D Imaging, Rhodos, Greece, September 1997.
[30] C.A. Micchelli, Interpolation of scattered data: distance matrices and conditionally positive definite functions, Construction Approximation 2 (1986) 11—22.
[31] Powell,M.J.D. Radial basis functions for multivariable interpolation:A review.In Algorithms for Approximation ,J.C.Mason and M.G.Cox,Eds.Oxford University Press,Oxford,UK,1987,pp.143 —167.
[32] Stanley Rhine. Tissue thickness measures: American caucasoids, amer-ican blacks, southwestern indians. Physical Anthropology Labratories, Maxwell Museum of Anthropology, University of New Mexico, 1982,1983,1984.
[33] F.Ulgen,A Step Toward Universal Facial Animation via Volume Morphing, 6th IEEE International Workshop on Robot and Human Communication, 1997,358-363
[34] Junyong Noh, Ulrich Neumann .Expression Cloning ,Proceeding of SIGGRAPH 2001, pages 277-288 ,August 2001
[35] W. Martin and J. Aggarwal, Motion Understanding Robot and Human Vision, Kluwer Academic Publishers,1988.
[36] Byoungwon Choe and Hyeong-Seok Ko. Analysis and Synthesis of Facial Expressions with Hand-Generated Muscle Actuation Basis. In the Proceedings of Computer Animation 2001 , pp. 12-19, Seoul, Korea, November 7-8, 2001
[37] P. Cignoni, C. Montani, R. Scopigno. A comparison of mesh simplification algorithms.Computers & Graphics 22,1,37-54
[38] G. Sannier, N. Magnenat-Thalmann. A User-Friendly Texture-Fitting Methodology for Virtual Humans. CGI 1997