K-Sketch: A Kinetic Sketch Pad for Novice Animators Richard C. Davis Electrical Engineering and Computer Sciences University of California at Berkeley Technical Report No. UCB/EECS-2008-171 http://www.eecs.berkeley.edu/Pubs/TechRpts/2008/EECS-2008-171.html December 18, 2008 Copyright 2008, by the author(s). All rights reserved. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission. K-Sketch: A Kinetic Sketch Pad for Novice Animators by Richard Christopher Davis B.S. (Massachusetts Institute of Technology) 1995 M.Eng. (Massachusetts Institute of Technology) 1995 A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Computer Science in the GRADUATE DIVISION of the UNIVERSITY OF CALIFORNIA, BERKELEY Committee in charge: Professor James A. Landay, Co-chair Professor John Canny, Co-chair Professor Carlo H. Séquin Professor Stephen Palmer Fall 2008 The dissertation of Richard Christopher Davis is approved: ___________________________________________________________________ Co-chair Date ___________________________________________________________________ Co-chair Date ___________________________________________________________________ Date ___________________________________________________________________ Date University of California, Berkeley Fall 2008 K-Sketch: A Kinetic Sketch Pad for Novice Animators © 2008 by Richard Christopher Davis 1 ABSTRACT K-Sketch: A Kinetic Sketch Pad for Novice Animators by Richard Christopher Davis Doctor of Philosophy in Computer Science University of California, Berkeley Professor James A. Landay, Co-chair Professor John Canny, Co-chair Animation is a powerful communication and visualization medium that is accessible to few, because current tools for creating animation are extremely complex. Simple animation tools exist, but they severely restrict the types of motion that can be expressed. To help novices create a wide range of animations quickly, I have developed a general-purpose, informal, 2D animation sketching system called K-Sketch, a kinetic sketch pad. My investigation began with field studies that explored the many uses of short, rough animations both by expert animators and would-be animators. The most significant results of these studies were evidence of the need for K-Sketch and a library of 72 usage scenarios for such a tool. These scenarios show how rough animation can be useful both to experts creating prototypes of animations and to novices creating animations for entertainment, visualization, or communication of dynamic concepts in a wide variety of educational or business settings. 2 While analyzing my library of scenarios, I identified 18 primitive animation operations that cover the most natural ways of expressing the motions and transitions in the animations I collected. To make K-Sketch simultaneously fast, simple, and expressive, I developed a novel interface optimization analysis method. I used this to visualize the tradeoffs of supporting various combinations of animation operations and choose a small but powerful set of capabilities for K-Sketch. This method and the tools I developed can be applied to many other domains. The final K-Sketch system uses pen input for sketching objects, intuitive demonstration of motion, and a suggestive interface for resolving ambiguous operations. In one laboratory experiment that compared K-Sketch to a more formal novice animation tool (PowerPoint), participants worked three times faster, needed half the learning time, and reported significantly lower cognitive load with K-Sketch. Another laboratory comparison with a less formal novice tool (The TAB Lite) showed that K-Sketch allows novices to express a wide range of animations quickly and intuitively. K-Sketch has been released to the world and is being used by over a thousand people to create rough animations. __________________________________________________ Professor James A. Landay Dissertation Committee Co-chair __________________________________________________ Professor John Canny Dissertation Committee Co-chair i For my twin brother William Rhett Davis in gratitude for years of creative energy Table of Contents ii Table of Contents CHAPTER 1 INTRODUCTION 1 1.1 Contributions 3 1.1.1 Concepts and Techniques 5 1.1.2 Artifacts 7 1.1.3 Study Results 10 1.2 Dissertation Outline 12 CHAPTER 2 RELATED WORK 14 2.1 Animation Culture 15 2.1.1 Amateur Animation for Entertainment 15 2.1.2 Novice Animation for Education 16 2.1.3 Animation Tools for Experts 20 2.1.4 Animation Tools for Novices 22 2.2 Pen-based Interfaces: Why and How 25 2.2.1 Sketching in Design 26 2.2.2 Creativity Support Research 28 2.2.3 A Brief History of Pen-based Interfaces 33 2.2.4 Sketching and Gesturing for Animation 38 2.2.5 Tools and Techniques 42 2.3 Motor and Perceptual Issues in Animation Sketching 46 2.3.1 Perception of Animations 46 2.3.2 Motor Control Issues in Animation Demonstration 48 2.4 Related Work Summary 50 CHAPTER 3 FIELD STUDIES 52 3.1 Interviews with Animators 54 3.2 Interviews with Non-Animators 64 3.3 Library of Usage Scenarios 74 Table of Contents iii 3.3.1 Gathering Scenarios 74 3.3.2 User Categories 77 3.3.3 Goal Categories 79 3.3.4 Animation Operations 81 CHAPTER 4 INTERFACE OPTIMIZATION 86 4.1 Coding the Scenario Library 88 4.2 Optimization Procedure 93 4.3 Interpreting Optimization Results 95 4.4 Generalizing and Improving Interface Optimization 103 CHAPTER 5 K-SKETCH DESIGN AND IMPLEMENTATION 107 5.1 The K-Sketch User Interface 108 5.1.1 Mode Switching in K-Sketch 110 5.1.2 Basic Animation 112 5.1.3 Selecting and Manipulating Objects 113 5.1.4 Overwriting and Adding Relative Motions 120 5.1.5 Cut, Copy, and Paste of Objects and Motions 131 5.1.6 Recording Drawings 137 5.1.7 Simplified Recording Controls 138 5.1.8 Speed Control 140 5.1.9 Simplified Time Navigation Controls 141 5.2 Examples of K-Sketch in Action 144 5.2.1 Scenario 55—Chemistry: Particle Collisions with K-Sketch 144 5.2.2 Scenario 30— Faerie Adventures 147 5.2.3 Scenario 46—Plane Story 148 5.2.4 Scenario 51— Detection of Distant Planets 151 5.3 Implementation 152 CHAPTER 6 FORMATIVE EVALUATIONS 160 6.1 Design Iterations 160 6.1.1 Early Design Sketches 161 6.1.2 Selection 164 6.1.3 Object Handle 168 Table of Contents iv 6.1.4 Recording Controls 170 6.1.5 Time Slider Bar 178 6.1.6 Adding Motions in New Reference Frames 183 6.2 Expert Animator Study 189 6.3 Formative Laboratory Evaluation 194 6.3.1 Method 195 6.3.2 Participants and Environment 197 6.3.3 Results 199 6.3.4 Discussion 201 CHAPTER 7 LABORATORY EVALUATIONS 204 7.1 Laboratory Study 1: Speed and Simplicity 206 7.1.1 Method 206 7.1.2 Participants 211 7.1.3 Environment 213 7.1.4 Results 214 7.1.5 Discussion 227 7.2 Laboratory Study 2: Expressivity 230 7.2.1 The TAB Lite 231 7.2.2 Method 233 7.2.3 Participants 242 7.2.4 Environment 244 7.2.5 Results 245 7.2.6 Discussion 265 CHAPTER 8 REAL-WORLD EVALUATIONS 275 8.1 Analysis of Usage Logs and Animation Files 276 8.1.1 Collecting Usage Logs and Animation Files 277 8.1.2 Comparing Against the Coded Scenario Library 281 8.1.3 Deeper Analysis of Files 289 8.2 Case Studies 297 8.2.1 User Interface Design Case Study 297 8.2.2 Science Learning Case Study 303 CHAPTER 9 FUTURE WORK 314 Table of Contents v 9.1 K-Sketch Enhancements 314 9.2 Improving Interface Optimization 317 9.3 Wizard of Oz Simulations of Dynamic Interface Behavior 318 9.4 End-user Prototyping of Games and Simulations 320 9.5 Managing Ideas Throughout Their Life Cycle 322 CHAPTER 10 CONCLUSION 325 10.1 Contributions 326 10.2 Toward Ubiquitous Animation 330 BIBLIOGRAPHY 332 APPENDIX A FIELD STUDY DATA 351 A.1 Animator 1 351 A.1.1 Notes on Initial Contact 352 A.1.2 Interview Questions 352 A.1.3 Images and Artifacts 353 A.2 Animator 2 360 A.2.1 Notes on Initial Contact 360 A.2.2 Interview Questions 360 A.2.3 Images and Artifacts 362 A.3 Animator 3 370 A.3.1 Notes on Initial Contact 371 A.3.2 Interview Questions 371 A.4 Animator 4 372 A.4.1 Notes on Initial Contact 373 A.4.2 Interview Questions 373 A.4.3 Images and Artifacts 374 A.5 Animator 5 375 A.5.1 Notes on Initial Contact 375 A.5.2 Interview Questions 375 A.5.3 Images and Artifacts 377 Table of Contents vi A.6 Animator 6 377 A.6.1 Notes on Initial Contact 378 A.6.2 Interview Questions 378 A.6.3 Images and Artifacts 379 A.7 Animator 7 380 A.7.1 Notes on Initial Contact 380 A.7.2 Interview Questions 380 A.7.3 Images and Artifacts 382 A.8 Animator 8 382 A.8.1 Notes on Initial Contact 383 A.8.2 Interview Questions 383 A.9 Non-animator 1 383 A.9.1 Notes on Initial Contact 383 A.9.2 Interview Questions 384 A.10 Non-animator 2 384 A.10.1 Notes on Initial Contact 385 A.10.2 Interview Questions 385 A.10.3 Images and Artifacts 386 A.11 Non-animator 3 388 A.11.1 Notes on Initial Contact 389 A.11.2 Interview Questions 389 A.11.3 Images and Artifacts 390 A.12 Non-animator 4 391 A.12.1 Notes on Initial Contact 391 A.12.2 Interview Questions 391 A.12.3 Images and Artifacts 392 A.13 Non-animator 5 392 A.13.1 Notes on Initial Contact 392 A.13.2 Interview Questions 392 A.13.3 Images and Artifacts 393 A.14 Non-animator 6 395 A.14.1 Notes on Initial Contact 395 A.14.2 Interview Questions 395 Table of Contents vii A.14.3 Images and Artifacts