在3D遊戲中，讓虛擬角色能夠在場景中自主的和使用者進行即時互動，一直是一個非常有挑戰性的問題。過去在此方面的相關研究雖然為數不少，但大多數的研究不是用效能來換取角色動作的規劃品質，就是屈就於效能而決定犧牲品質，能妥善的在兩者之間取得平衡的系統並不常見。本論文所提出的系統，便是一個能在兩者之間取得不錯平衡的角色動作規劃器。我們的規劃器會根據使用者的操作命令來預測角色未來可行的行動空間，並搭配時間預算的概念，將這些預測結果儲存在一種稱為可行動作樹的資料結構，從這些預測結果中搜尋出最符合使用者操作要求的角色動作。我們利用這個規劃器實作了兩種不同的應用，並測試了它們的效能。我們相信這個運動模組能實用在一般如遊戲的即時動畫環境中，提昇動畫角色的互動性與動畫品質。

Allowing a virtual character to interact with the user autonomously in a 3D game has been a challenging problem for long. There has been much research in this direction but most of them have to trade interactivity of control with the quality of the generated motions or the other way. It is rare to see a system that can find a good balance between these two factors. In this thesis, we propose an interactive system consisting of a motion planner aiming to find a good balance between these two factors. Our planner attempts to predict the feasible motion space in the near future according to user commands. We use the concept of time-budgeted computing to maintain a data structure called Feasible Motion Tree representing the feasible motion space. This tree is maintained in an incremental fashion and is used to select the most appropriate motion clip when the current motion clip comes to the end. We have used this motion planning module to implement two different applications and verify its efficacy and efficiency. We believe that this motion planning module can be used in a real-time virtual environment, such as a game, for the improvement of the interactivity and the quality of motion control.

[1] A. Bruderlin and T. W. Calvert, “Goal-Directed, Dynamic Animation of Human Walking,” in Proc. of the ACM SIGGRAPH, 1989.
[2] A. C. Fang and N. S. Pollard, “Efficient Synthesis of Physically Valid Human Motion,” in Proc. of the ACM SIGGRAPH, 2003.
[3] B. L. Callennec and R. Boulic, “Interactive Motion Deformation with Prioritized Constraints,” in Proc. of the ACM SIGGRAPH / Eurographics Symposium on Computer Animation, 2004.
[4] B. Salomon, M. Garber, M.C. Lin and D. Manocha, “Interactive Navigation in Complex Environments Using Path Planning,” in Proc. of the Symposium on Interactive 3D Graphics, p41-50, 2003.
[5] C. K. Liu and Z. Popovic, “Synthesis of Complex Dynamic Character Motion from Simple Animations,” in Proc. of the ACM SIGGRAPH, 2002.
[6] CMU Graphics Lab Motion Capture Database
http://mocap.cs.cmu.edu/
[7] E. Hsu, Kari Pulli and Jovan Popovic, “Style Translation for Human Motion,” in Proc. of the ACM SIGGRAPH, 2005.
[8] G., V. den Bergen, “Efficient Collision Detection of Complex Deformable Models Using AABB Trees,” Journal of Graphics Tools, 2, (4): 1-14, 1997.
[9] H. C. Sun and D. Metaxas, “Automating Gait Generation,” in Proc. of the ACM SIGGRAPH, 2001.
[10] H. Ko and Norman I. Badler, “Animating Human Locomotion with Inverse Dynamics,” IEEE Transaction on Computer Graphics, 16(2), pp.50-59. 1996.
[11] H. Li, W. Tang and D. Simpson, “Behaviour Based Motion Simulation for Fire Evacuation Procedures,” in Proc. of the Theory and Practice of Computer Graphics, 2004.
[12] J. K. Hodgins, “Three-Dimensional Human Running,” in Proc. of the IEEE Conference on Robotics and Automation, 1996.
[13] J. K. Hodgins, W. L. Wooten, D. C. Brogan and J. F. O'Brien, “Animating Human Athletics,” in Proc. of the ACM SIGGRAPH, 1995.
[14] J. Lee and K. H. Lee, “Precomputing Avatar Behavior from Human Motion Data,” in Proc. of the ACM SIGGRAPH / Eurographics Symposium on Computer Animation, 2004.
[15] J.Y. Chang and T.Y. Li, "Simulating Crowd Motion with Shape Preference and Fuzzy Rules," in Proc of International Symposium on Artificial Life and Robotics, 2007.
[16] L. Kavraki, P. Svestka, J.C. Latombe and M. H. Overmars, “Probabilistic Roadmaps for Path Planning in High-Dimensional Configuration Space,” in IEEE Trans. On Robotics and Animation, 12, (4): 566-580, 1996.
[17] L. Kovar, M. Gleicher and F. Pighin, “Motion Graphs,” in Proc. of the ACM SIGGRAPH, 2002.
[18] M. Gleicher, H. Shin, Lucas Kovar and Andrew Jepsen, “Snap-Together Motion: Assembling Run-Time Animations,” in Proc. of Symposium on Interactive 3D Graphics. 2003.
[19] M. Kallmann, A. Aubel, T. Abaci, and D. Thalmann, “Planning Collision-Free Reaching Motions for Interactive Object Manipulation and Grasping,” in Proc. of Eurographics, 2003.
[20] M. Lau and J. Kuffner, “Behavior Planning for Character Animation,” in Proc. of the ACM SIGGRAPH / Eurographics Symposium on Computer Animation, 2005.
[21] M. Lau and J. Kuffner, “Precomputed Search Trees: Planning for Interactive Goal-Driven Animation,” in Proc. of the ACM SIGGRAPH / Eurographics Symposium on Computer Animation, 2006.
[22] M.H. Overmars and P. Svestka, “A probabilistic Learning Approach to Motion Planning,” in Proc. of the Workshop on Algorithmic Foundations of Robotics, p19-37, 1995.
[23] O. Arikan and D.A. Forsyth, “Interactive Motion Generation from Examples,” in Proc. of the ACM SIGGRAPH, 2002.
[24] S.M. Lavalle, “Rapidly-Exploring Random Trees: A New Tool for Path Planning,” Technical Report, Computer Science Dept., Iowa State University, 1998.
[25] S.W. Hsu and T.Y. Li, "Third-Person Intelligent Control of Humanoid with Real-Time Motion Planning Algorithm," in Proc of IEEE International Conference on Intelligent Robots and Systems, 2006.
[26] T.Y. Li, P.F. Chen and P.Z. Huang, “Motion Planning for Humanoid Walking in a Layered Environment.” in Proc. of the IEEE Int. Conf. on Robotics and Automation, p3421-3427, 2003.
[27] T. Simeon, J.-P. Laumond. and C. Nissoux, “Visibility-based probabilistic roadmaps for motion planning,” Advanced Robotics Journal, 14(6).
[28] W. Shao and D. Terzopoulos, “Autonomous Pedestrians,” in Proc. of the ACM SIGGRAPH / Eurographics Symposium on Computer Animation, 2005.
[29] M. Sung, L. Kovar and M. Gleicher, “Fast and accurate goal-directed motion synthesis for crowds,” in Proc. of the ACM SIGGRAPH / Eurographics Symposium on Computer Animation, 2005.
[30] J. Lee and L.H Lee, “Interactive Control of Avatars Animated with Human Motion Data,” in Proc. of the ACM SIGGRAPH, 2002.
[31] A. P. Witkin and Z. Popovic, “ Motion warping,” in Proc. of the ACM SIGGRAPH, 1995.