By Lisa Mohan and Itay Neeman
 
After completing her undergraduate math degree at DePauw University in her home state of Indiana, Aleka McAdams ventured to the West Coast seeking a graduate program in applied mathematics and milder winters. At the UCLA Math department's open house for prospective graduate students, she found an inviting research climate. Says Aleka, "I was interested in image processing when I initially came to UCLA. I had done some research in that as an undergraduate, and the UCLA image processing group is very strong. I was also impressed that this wasn't the only thing the applied math group does that is highly ranked." In 2006 when Aleka began her studies, U.S. News & World Report's best graduate schools survey ranked the department's applied math research program at number four in the nation. In the latest 2010 survey, it stands at number two.

Aleka shifted direction in her first year after taking a computational fluid dynamics class and discovering simulation, which has numerous applications in engineering, atmospheric sciences and special effects for the film and television industry. Soon after, Joseph Teran, one of the most promising young computational scientists in the country, joined the department's applied math faculty. Aleka found that Teran's focus on scientific computing and physics-based simulations were a good fit for her newfound interest. Teran quickly became her PhD advisor. Inspired by his graduate seminar in continuum mechanics, Aleka began her specialization in physics-based simulation and computer graphics for movie special effects. Says Aleka, "The big thing that started me off was when Joey helped me land an internship with Walt Disney Animation Studios, and I began doing research for hair simulation." Her efforts resulted in a paper with Teran and Disney collaborators that was accepted by the 2009 SIGGRAPH conference on computer graphics and interactive techniques. "Detail Preserving Continuum Simulation of Straight Hair" presented a method to tackle hair simulation, one of the most challenging aspects of creating virtual characters for the movie industry. The massive number of hairs interacting and colliding makes the simulation especially challenging, and although many approximations for simulating hair exist, they typically fail to provide the amount of detail that real hair exhibits. Their technique presented a hybrid Eulerian/Lagrangian approach to handling both self and body collisions with hair efficiently while still maintaining detail.

Aleka's hair simulation results led to her next research and development internship at Weta Digital, film director Peter Jackson's visual effects company in New Zealand. There, she collaborated on a second paper focusing on a multigrid Poisson solver for high resolution fluid simulations. The method can be used to simulate phenomena such as smoke and water animations. Says Aleka, "The idea is to adapt to new computer architectures by coming up with an algorithm which is highly parallelizable, which means that it can run in parallel on multiple processors at the same time to increase speed." The source code has been published and adapted for use by movie studios.

Returning to Disney for her final student internship, Aleka focused on using deformable object simulation for animated characters. In particular, she and her collaborators were interested in skeleton-driven character skinning, which allows animators to define the motion of a character's skin by moving its underlying skeleton. By using elasticity simulation techniques, they could produce life-like deformations such as muscle bulges in character animations. While many such techniques exist, they are typically too computationally expensive for animation. To this end, they developed a new highly parallelizable algorithm for elasticity simulation.

Aleka enjoys the challenge of physical simulation techniques for special effects, which differ from those developed for more classical applications in physics and engineering. Engineers designing a bridge, for example, run simulations to test building materials for real outcomes. In movies, the artistic vision of a scene requires a high level of controllability in the outcome of a simulation. Says Aleka, "In special effects, you know that you want the bridge to collapse and there are certain parts of it that you want to control where they fall and what happens, so you want to use simulation to create a more real looking result but also make it easily directable by the artist."

The internships and industry experience landed Aleka a permanent position at Walt Disney Animation Studios, where last June she started as a senior software engineer in the Look, Effects and Dynamics department. In addition to continuing her work on specific simulation techniques, she has turned her focus to tools for rendering, the process of transforming data into final images. While many of her Disney colleagues have computer science backgrounds, Aleka credits her UCLA applied math education and the connections it provided for boosting her up the career ladder: "I had the opportunity to learn about industry-level problems, which was really useful. Also, the UCLA applied math program can be very computational, so I gained a lot of valuable experience with programming."

Published in Winter 2012