Papers by Theodore Kim


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Analytic Eigensystems for Isotropic Distortion Energies

Breannan Smith, Fernando de Goes, Theodore Kim
September 2018

Many strategies exist for optimizing non-linear distortion energies in geometry and physics applications, but devising an approach that achieves the convergence promised by Newton-type methods remains challenging. In order to guarantee the positive semi-definiteness required by these methods, a numerical eigendecomposition or approximate regularization is usually needed. In this paper, ... more

Paper (PDF)

Additional materials: [movie.mov], [Matlab.zip], [supplement.pdf]


Clean Cloth Inputs: Removing Character Self-Intersections With Volume Simulation

Audrey Wong, David Eberle, Theodore Kim
August 2018

Simulation artists frequently work with characters that self-intersect. When these characters are sent as inputs to a cloth simulator, the results can often contain terrible artifacts that must be addressed by tediously sculpting either the input characters or the output cloth. In this talk, we apply volume simulation to character ... more

Paper (PDF)


Example-based Turbulence Style Transfer

Syuhei Sato, Yoshinori Dobashi, Theodore Kim, Tomoyuki Nishita
August 2018

Generating realistic fluid simulations remains computationally expensive, and animators can expend enormous effort trying to achieve a desired motion. To reduce such costs, several methods have been developed in which high-resolution turbulence is synthesized as a post process. Since global motion can then be obtained using a fast, low-resolution simulation, ... more

Paper (PDF)

Additional materials: [FluidStyleTransfer_Supplemental.mp4], [FluidStyleTransfer.mp4]


Robust Skin Simulation in Incredibles 2

Ryan Kautzman, Gordon Cameron, Theodore Kim
August 2018

Robustly simulating the dynamics of skin sliding over a character's body is an ongoing challenge. Skin can become non-physically "snagged" in curved or creased regions, such as armpits, and create unusable results. These problems usually arise when it becomes ambiguous which kinematic surface the skin should be sliding along. We ... more

Paper (PDF)


Scalable Laplacian Eigenfluids

Qiaodong Cui, Pradeep Sen, Theodore Kim
August 2018

The Laplacian Eigenfunction method for fluid simulation, which we refer to as Eigenfluids, introduced an elegant new way to capture intricate fluid flows with near-zero viscosity. However, the approach does not scale well, as the memory cost grows prohibitively with the number of eigenfunctions. The method also lacks generality, because ... more

Paper (PDF)

Additional materials: [ScalableEigenFluidSupplementalVideo.mp4], [supplement.pdf], [ScalableEigenFluidMainVideo.mp4]


Stable Neo-Hookean Flesh Simulation

Breannan Smith, Fernando de Goes, Theodore Kim
December 2017

Non-linear hyperelastic energies play a key role in capturing the fleshy appearance of virtual characters. Real-world, volume-preserving biological tissues have Poisson's ratios near 1/2, but numerical simulation within this regime is notoriously challenging. In order to robustly capture these visual characteristics, we present a novel version of Neo-Hookean elasticity. Our ... more

Paper (PDF)

Video

Additional materials: [snh_code.tar.bz2], [stable_neo_hookean_supplement.pdf]

Accepted to ACM Transactions on Graphics


Dispersion Kernels for Water Wave Simulation

Jose Angel Canabal, David Miraut, Nils Thuerey, Theodore Kim, Javier Portilla, Miguel Otaduy
December 2016

We propose a method to simulate the rich, scale-dependent dynamics of water waves. Our method preserves the dispersion properties of real waves, yet it supports interactions with obstacles and is computationally efficient. Fundamentally, it computes wave accelerations by way of applying a dispersion kernel as a spatially variant filter, which ... more

Paper (PDF)


Eulerian Solid-Fluid Coupling

Yun Teng, David I.W. Levin, Theodore Kim
December 2016

We present a new method that achieves a two-way coupling between deformable solids and an incompressible fluid where the underlying geometric representation is entirely Eulerian. Using the recently developed Eulerian Solids approach [Levin et al. 2011], we are able to simulate multiple solids undergoing complex, frictional contact while simultaneously interacting ... more

Paper (PDF)


Compressing Fluid Subspaces

Aaron Demby-Jones, Pradeep Sen, Theodore Kim
May 2016

Subspace fluid simulations, also known as reduced-order simulations, can be extremely fast, but also require basis matrices that consume an enormous amount of memory. Motivated by the extreme sparsity of Laplacian eigenfunctions in the frequency domain, we design a frequency-space codec that is capable of compressing basis matrices by up ... more

Paper (PDF)


Subspace Condensation: Full Space Adaptivity for Subspace Deformations

Yun Teng, Mark Meyer, Tony DeRose, Theodore Kim
May 2015

Subspace deformable body simulations can be very fast, but can behave unrealistically when behaviors outside the prescribed subspace, such as novel external collisions, are encountered. We address this limitation by presenting a fast, flexible new method that allows full space computation to be activated in the neighborhood of novel events ... more

Paper (PDF)

Additional materials: [paper_0089.mov]

To appear in SIGGRAPH 2015.

Available as Pixar Technical Memo #15-03