Guided Control of Intelligent Virtual Puppets Daniel Alexander Taranovsky A thesis subniitted in conformity with the requirements for the degree of Master of Science. Graduate Department of Cornputer Science University of Toronto O Copyright by Daniel Alexander Taranovsky 2001 National Library Bibliothèque nationale 141 of Canada du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. rue Wellington Ottawa ON K1A ON4 Ottawa ON K1A ON4 Canada Canada Your a7 votm nllefeme Our file Noire réMnmce The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant a la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or seil reproduire, prêter, distribuer ou copies of this thesis in microfonn, vendre des copies de cette thèse sous paper or electronic formats. la forme de rnicrofiche/film., de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts from it Ni la thèse ni des extraits substantiels may be printed or otherwise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Abstract Guided Control of Intelligent Virtual Puppets Daniel Alexander Taranovsky Master of Science, 200 1 Graduate Department of Computer Science, University of Toronto Controlling the motion of virtual characters with many degrees of freedom can be difficult and time consuming. For some applications, cornplete control over dljoints at every time step is not necessary and actually hinders the creative process, However, endowing the character with autonomous behaviour and decision-making capabilities completely absolves the user of clearly speciQing his intentions. In many circumstances the ideal level of control dlows the user to specify motion in terms of high-level tasks with timing and stylistic parameters. The user is not encumbered by low-level details, while retaining complete control over the motion's semantic interpretation. This relatively unexplored level of motion specification is terrned "guided control", and is the focus of our work, We present the issues and results encountered from implementing a prototype animation system with guided control of a virtud Puppet. Acknowledgements Knowlege: Ye euery man whan ye to deth shall go But not yet for no maner of daunger. Eueryman: Gramercy, Knowlege, with al1 my herte- Knowlege: Nay, yet 1 wyll not from hens departe Tyll 1 se where ye shall become. Everyman, Scene 17. John Skot (1521-1537?) 1 am most thankfûl for my mother, father, and brother, whose unfaltering support and encouragement has made everything possible. This thesis is dedicated to them. I am privileged to have worked arnong the talented, dedicated people at the Dynarnic Graphics Project. 1 thank my supervisor Michiel van de Panne for his patient and knowledgeable advice. Professor van de Panne's comments and constructive scrutiny greatly improved the work. My second reader, James Stewart, also diligently read my thesis. L am grateful to both of these men for their guidance and suggestions. Petros Faloutsos and Joe Laszlo were always generous with their time and deserve special thanks for their technical help. 1 acknowledge the financial support of the Govemment of Ontario, the University of Toronto, and the Department of Computer Science. Table of Contents 1 Introduction ............................................................................................................ 1 1.1 Motivation ....................................................................................................... 2 1-2 Thesis Contributirons ........................................................................................ 4 1.3 Potential Applicaitions .................................... .... 5 1-4 Thesis Organizati. on ...................................................................................... 5 1.5 Summary ............ - ............................................................................................. 6 2 Literature Survey...... -............................................................................................ -7 2.1 Characterizing Animation Techniques............................................................. 8 2.2 Kinematic SpeciEcation of Articulated Figures ....................................... 12 2.3 Keyframing Techmiques ................................................................................. 15 2.4 Positioning Articlalated Figures with Inverse Kinematics ............................. 17 2.5 Motion Capture arid Motion Processing ........................................................ 20 2.6 D ynamic Techniqwes ..................................................................................... -22 2.7 Behavioural Techmiques ................................................................................. 25 2.8 Interactive Controd ......................................................................................... 26 2.9 Ergonomies .................................................................................................... 31 2.10 Biomechanics ........................................ .... .................................................. -32 2.1 1 Sumrnary ......... .. .... ,. ..................................................................................... 41 3 System Overview ................................................................................................ -42 3 -1S ystem Architecture ...................................................................................... -44 3 -2 System Modules ...................................................... 3.2.1 Interface .................................................. ............................................. 46 3.2.2 Motion Scheduler ................................................................................. 47 3 .2.3 Posture Generator................... .............................................................. 47 3-3 User Input ....................................................................................................... 48 3.4 Environment ....... ... .................................................................................-.-- 49 3.5 Virtual Puppet ..................... ....... .......................................................... 52 3.6 Motion Queue *.......*............ ... .................................................................. 56 3.6.1 Motion Building Blocks ............ ..... .......... .... .............................. 57 3.6.2 Cyclic Motion ...................................................................................... 59 3.6.3 Critical Body Segments ....................................................................... 60 3.7 Summary ........................................................................................................ 61 4 Motion Scheduling ............................................................................................... 62 4.1 Introducing Motion Concurrency................................................................... 63 4.2 Motion Scheduler Operation .......... ... ......................................................... 65 4.3 Motion Concurrency Algorithm .................................................................... 71 4.4 Removing Tasks ............................................................................................. 77 4.5 Animating the Virtual Puppet ........................................................................ 82 4.6 Surnmary ............................ ... .................................................................. 86 5 Posture Generator ................................................................................................. 87 5.1 Solving Inverse Kinematics ........................................................................... 89 5.2 Overview of M Algorithm .............. ... ............................................................ 96 5.3 2D Inverse Kinematics ................................................................................... 96 5.4 Properties of the Algorithm........................................................................... 96 5.5 3D Inverse Kinematics................................................................................. 102 5.6 Coping with ColIisions ................... .. ...................................................... 107 5.7 Natural Postures ........................................................................................... 111 5.7.1 Estimating Arm Position ........... .... ............................................... 114 5.7.2 Estimating Torso Position .................................................................. 115 5.7.3 Weight Schemes................................................................................. 118 5.7.4 Score Functions ................................................................................. 131 5.7.5 Distributing Iterations .......................... .... ........................................ 124 5.8 Summary ...................................................................................................... 128 6 Motion Interface ........... .... ................................................................................ 129 6.1