Real-time deformation brings 3D characters to life. Methods developed in recent years abound throughout computer games, film production, medical simulations and augmented reality systems. This course examines the motivation and methodology behind the state-of-the-art deformation techniques. Traditionally, animators articulate a 3D character by propagating the deformations of an internal skeleton made of rigid bones to the "skin" of the character. The character's geometry might be arbitrary complex but so long as the number of bones is small "skinning" a character is fast. Many linear and non-linear techniques were introduced to blend contributions of individual bones using either the rest-pose alone or a database of example shapes. The blending weights used to be painted manually but several automatic techniques are now available. This course summarizes these recent developments including the application of skinning to arbitrary animations. The course is organized into two parts. We first review the traditional skinning pipeline, discussing a variety of linear and non-linear transformation blending methods. Next we show how manual skeleton construction and hand-painting can be avoided with automatic methods. We categorize desired qualities and demonstrate how each may be modeled as a continuous energy or constraint resulting in a optimization discretized using finite-element method and solved efficiently with modern sparse quadratic programming solvers. Lastly, we direct audience members to our course page http://skinning.org for more detailed information and additional lectures on example-based skinning and skinning for mesh animation decomposition.

Level

Prerequisites

N/A

Intended Audience

The intended audience of this course are computer graphics practitioners and researchers, from technical directors to programmers or students.

Presenter(s)

Alec Jacobson, Columbia University
Yotam Gingold, Rutgers University

Alec Jacobson is a post-doctoral researcher at Columbia University. He received a BA and an MA in Mathematics and Computer Science from the Courant Institute of Mathematical Sciences, New York University, and a PhD in Computer Science from ETH Zurich. His thesis on real-time deformation techniques for 2D and 3D shapes was awarded the ETH Medal and the Eurographics Best PhD award. His research incorporates finite-element method and constrained optimization to design automatic weighting functions for skinning. He is also interested in novel input devices for character animation and robust meshing techniques for 3D volumes. He has published several papers in the proceedings of SIGGRAPH.

Yotam Gingold is an Assistant Professor in the computer science department at George Mason University. He runs the Creativity and Graphics Lab (CraGL), whose mission is to solve challenging visual, geometry, and design problems and pursue foundational research into human creativity. His work is supported by the National Science Foundation and Google. Previously he was a post-doctoral researcher in the computer science departments of Columbia University, Rutgers University, Tel-Aviv University, and Herzliya IDC. Yotam earned his Ph.D. in Computer Science from New York University in 2009, where he was awarded the Janet Fabri Prize for most outstanding dissertation.