在本篇論文中，我們提出一種基於影片的動畫模仿系統，透過
擷取影片中人物之動作，我們可以將此動作再利用；首先，我們使
用動畫師一開始給定的二維骨架作追蹤，之後再將動作套用到新的
角色上，藉由以影片當來源，一段新的動畫會被產生，其新的角色
會模仿原影片的人物動作，但卻會有完全不一樣的外表。
動畫模仿系統是由以下幾個步驟所完成，首先，我們會要求動
畫師在影片的第一個影格點選出所有關節點，並將關節點組合成一
骨架，之後系統利用Optical Flow 計算出關節在接續影格中 的 位
置，接下來，捕捉下來的動作資訊將會輸入到一二維形變的演算法，
最後產生基於原影片的動畫。
動畫模仿系統結合這些既有的演算法藉以產生動畫，最後的動
畫雖然粗略，卻可讓動畫師基於此動畫做進一步的修改，節省動畫
師許多寶貴的時間。

In this thesis, we propose a new system for capturing animation by detecting character motions in a single video stream We track the motion by using the skeleton model that animators provide and retarget the motion onto 2D drawings. By using video sequences as the source, a new animation is created with a different look but will imitate the movement of the original character in the video.
The animation imitate process is done through first track the motion by calculating the optical flow of succeeding frames, for this step we will ask animators to specify all the feature points and join the feature points to be a 2D skeleton model with hierarchical structure. We then apply a shape deformation method that will keep the shape rigidity of the original 2D retargeting character. By combining these existing methods, our system can produce rough animations that an animator can then further modify the animations and do some additional refinements.

[1] John Lasster. Principles of Traditional Animation Applied to 3d
Computer Animation. In Proceedings of SIGGRAPH 1987.
[2] Johnston and Thomas. The Illusion of Life: Disney Animation. Disney
Editions 1995.
[3] D.M Gavila. The Visual Analysis of Human Movement: A Survey. Computer
Vision and Image Understanding 1999.
[4] Jean-Yves Bouguet. Pyramidal Implementation of the Lucas Kanade
Feature Tracker Description of the Algorithm. Technical Report 2000.
[5] Alexa M. As-Rigid-As Possible Shape Interpolation. In Proceedings of
ACM SIGGRAPH 2000.
[6] Michael Gleicher. Evaluating Video-Based Motion Capture. In
Proceedings of Computer Animation 2002.
[7] Christoph Bregler. Turning to the Masters: Motion Capture Cartoons.
In Proceedings of ACM SIGGRAPH 2002.
[8] James Davis. A Sketching Interface for Articulated Figure Animation.
In Proceedings of ACM SIGGRAPH/Eurographics Symposium on Computer
Animation 2003.
[9] Ignacio Llamas. Twister: A Space-Warp Operator for the Two-Handed
Editing of 3D Shapes. ACM Transactions on Graphics 2003.
[10]Aseem Agarwala. Keyframe-Based Tracking for Rotoscoping and
Animation. In Proceedings of ACM SIGGRAPH 2004.
[11]Matthew Thorne. Motion Doodles: An Interface for Sketching Character
Motion. ACM Transactions on Graphics 2004.
[12]Laurent Favreau. Animal Gaits From Video. In Proceedings of ACM
SIGGRAPH/Eurographics Symposium on Computer Animation 2004.
[13]Takeo Igarashi. As-Rigid-As Possible Shape Manipulation. ACM
Transactions on Graphics 2005.
[14]Ignacio Llamas. Bender: A Virtual Ribbon for Deforming 3D Shpaes in
Biomedical and Styling Aplications. In Proceedings of ACM Symposium
on Solid and Physical Modeling 2005.
[15]Schaefer S. Image Deformation Using Moving Least Squares. In
Proceedings of ACM SIGGRAPH 2006
[16]Jue Wang. The Cartoon Animation Filter. In Proceedings of ACM SIGGRAPH
2006.