Aesthetic edits for character animation

Our progress in the problem of making animated characters move expressively has been slow, and it persists in being among the most challenging in computer graphics. Simply attending to the low-level motion control problem, particularly for physically based models, is very difficult. Providing an animator with the tools to imbue character motion with broad expressive qualities is even more ambitious, but it is clear it is a goal to which we must aspire. Part of the problem is simply finding the right language in which to express qualities of motion. Another important issue is that expressive animation often involves many disparate parts of the body, which thwarts bottom-up controller synthesis. We demonstrate progress in this direction through the specification of directed, expressive animation over a limited range of standing movements. A key contribution is that through the use of high-level concepts such as character sketches, actions and properties, which impose different modalit...

Proceedings of the 2009 ACM SIGGRAPH/Eurographics Symposium on Computer Animation, 2009

Animation data, from motion capture or other sources, is becoming increasingly available and provides high quality motion, but is difficult to customize for the needs of a particular application. This is especially true when stylistic changes are needed, for example, to reflect a character's changing mood, differentiate one character from another or meet the precise desires of an animator. We introduce a system for editing animation data that is particularly well suited to making stylistic changes. Our approach transforms the joint angle representation of animation data into a set of pose parameters more suitable for editing. These motion drives include position data for the wrists, ankles and center of mass, as well as the rotation of the pelvis. We also extract correlations between drives and body movement, specifically between wrist position and the torso angles. The system solves for the pose at each frame based on the current values of these drives and correlations using an efficient set of inverse kinematics and balance algorithms. An animator can interactively edit the motion by performing linear operations on the motion drives or extracted correlations, or by layering additional correlations. We demonstrate the effectiveness of the approach with various examples of gesture and locomotion.

ACM Transactions on Graphics, 2016

We introduce staggered poses---a representation of character motion that explicitly encodes coordinated timing among movement features in different parts of a character's body. This representation allows us to provide sparse, pose--based controls for editing motion that preserve existing movement detail, and we describe how to edit coordinated timing among extrema in these controls for stylistic editing. The staggered pose representation supports the editing of new motion by generalizing keyframe--based workflows to retain high--level control after local timing and transition splines have been created. For densely--sampled motion such as motion capture data, we present an algorithm that creates a staggered pose representation by locating coordinated movement features and modeling motion detail using splines and displacement maps. These techniques, taken together, enable feature--based keyframe editing of dense motion data.

IEEE Transactions on Visualization and Computer Graphics, 2000

The squash-and-stretch describes the rigidity of the character. This effect is the most important technique in traditional cartoon animation. In this paper, we introduce a method that applies the squash-and-stretch effect to character motion. Our method exaggerates the motion by sequentially applying the spatial exaggeration technique and the temporal exaggeration technique. The spatial exaggeration technique globally deforms the pose in order to make the squashed or stretched pose by modeling it as a covariance matrix of joint positions. Then, the temporal exaggeration technique computes a time-warping function for each joint, and applies it to the position of the joint allowing the character to stretch its links appropriately. The motion stylized by our method is a sequence of squashed and stretched poses with stretching limbs. By performing a user survey, we prove that the motion created using our method is similar to that used in 2D cartoon animation and is funnier than the original motion for human observers who are familiar with 2D cartoon animation.

Cartoonists and animators often use lines of action to emphasize dynamics in character poses. In this paper, we propose a physically-based model to simulate the line of action's motion, leading to rich motion from simple drawings. Our proposed method is decomposed into three steps. Based on user-provided strokes, we forward simulate 2D elastic motion. To ensure continuity across keyframes, we re-target the forward simulations to the drawn strokes. Finally, we synthesize a 3D character motion matching the dynamic line. The fact that the line can move freely like an elastic band raises new questions about its relationship to the body over time. The line may move faster and leave body parts behind, or the line may slide slowly towards other body parts for support. We conjecture that the artist seeks to maximize the filling of the line (with the character's body)---while respecting basic realism constraints such as balance. Based on these insights, we provide a method that synth...

In comparison to traditional animation techniques, motion capture allows animators to obtain a large amount of realistic data in little time. The motivation behind our research is to try to fill the gap that separates realistic motion from cartoon animation. With this, classical animators can produce high quality animated movies (such as Frozen, Toy Story, etc.) and non-realistic video games in a significantly shorter amount of time. To add cartoon-like qualities to realistic animations, we suggest an algorithm that changes the animation curves of motion capture data by modifying local minima and maxima. We also propose a curve-based interface that allows users to quickly edit and visualize the changes applied to the animation. Finally, we present the results of two user studies that evaluate both the overall user satisfaction with the system's functionality, interactivity and learning curve, and the animation quality. vii

2005

Character animation remains a very challenging task despite many years of research on improved tools and algorithms. Production-quality animation is extremely slow to produce and only a small number of skilled animators are capable of creating it. This thesis Dedicated with love to my mother, Diane Neff, my grandma and grampa, Ken and Eunice Whiteley, and my sister, Christine. v Eugene Fiume has served as my advisor throughout my time at the U of T. I doubt this work would have been possible working under someone else. Eugene gave me the freedom to work outside of the normal orthodoxy of computer science and ceaselessly encouraged my efforts. Rare was a time that I would leave his office and not be more excited about my work than when I had entered. Eugene also set very important standards for what constitutes quality research and encouraged me to constantly question the position and impact of my work. I've learnt a great deal from Eugene-many things having little to do with computer science. As a young animation researcher, I had a Dream Team for a Ph.D. committee that along with Eugene included Demetri Terzopoulos, Michiel van de Panne and Craig Boutilier. It has been a privilege to hear their thoughts on my work. I would like to particularly thank Michiel for being consistently generous with his time, both when he was a stalwart of DGP in the early days of my thesis, and later when he had moved west. Norman Badler served as the external appraiser for this thesis and was the consummate professional, all on a very short timeline. I appreciate his efforts. Stephen Johnson-a professor at the Graduate Centre for Studies in Drama, a former teacher and a friend-provided important guidance to the arts literature during the early stages of this work. DGP has been a rich environment in which to conduct my graduate work and there are a great number of people worth mentioning that have helped make it so. I'll only highlight a few who were particularly significant to my work, with apologies to the rest: Petros Faloutsos and Victor Ng-Thow-Hing (the fathers of DANCE and generous tutors); Joe Laszlo (paper collaborator and man of endless ideas); Sageev Oore (research collaborator and great for all things artistic, musical or zany); Dave Mould, Glenn Tsang and Chris Trendall (many discussions on all things computer science and not); Qinxin Yu (many vi discussions and an always positive disposition as my desk neighbour during the last few years). John Hancock and Alan Rosenthal have also provided excellent support as lab administrators. Financial support which made this work possible was provided by NSERC and the Department of Computer Science. It is hard to imagine a more rich and enjoyable community than is provided by Massey College. Many of my best memories from the U of T were there and I thank my college friends for discussions and distractions both. Hopefully we will share a beer again. Gene was my roommate throughout my entire time at grad school and, incredibly, never complained about my changing moods or stressed out moments during the process of this work-a true friend indeed. A big cheers as well to the rest of the Perth crowd:

Intelligent Virtual Agents, 2015

We present a Matlab toolbox for synthesis and visualization of human motion style. The aim is to support development of expressive virtual characters by providing implementations of several style related motion synthesis methods thus allowing side-by-side comparisons. The implemented methods are based on recorded (captured or synthetic) motions, and include linear motion interpolation and extrapolation, style transfer, rotation swapping per body part and per quaternion channel, frequency band scaling and swapping, and Principal/Independent Component Analysis (PCA/ICA) based synthesis and component swapping.

The Rise of the Creative Economy. The 23th Society for Animation Studies Annual Conference, 2013

The current paper develops a researching line connecting arts, new technologies and animation, as part of a wider project that delves into disrupting languages and Theory of Animation, focusing on artistic and experimental animation. This paper is indebted to the invaluable contribution of numerous animation artists, who shared with us via an open survey their experiences and opinions concerning the newly available technologies, and how they have influenced — or not — the evolution of their animation style: new resources and possibilities of digital production, advantages have they discovered, and which disadvantages they endure, ultimately providing innovative ideas to achieve better results.