Category: Uncategorized

“The isosurface stuffing algorithm fills an isosurface with a uniformly
sized tetrahedral mesh whose dihedral angles are bounded
between 10.7◦ and 164.8◦, or (with a change in parameters) between
8.9◦ and 158.8◦. The algorithm is whip fast, numerically robust,
and easy to implement because, like Marching Cubes, it generates
tetrahedra from a small set of precomputed stencils. A variant
of the algorithm creates a mesh with internal grading: on the boundary,
where high resolution is generally desired, the elements are fine
and uniformly sized, and in the interior they may be coarser and
vary in size. This combination of features makes isosurface stuffing
a powerful tool for dynamic fluid simulation, large-deformation
mechanics, and applications that require interactive remeshing or
use objects defined by smooth implicit surfaces. It is the first algorithm
that rigorously guarantees the suitability of tetrahedra for
finite element methods in domains whose shapes are substantially
more challenging than boxes. Our angle bounds are guaranteed by
a computer-assisted proof. If the isosurface is a smooth 2-manifold
with bounded curvature, and the tetrahedra are sufficiently small,
then the boundary of the mesh is guaranteed to be a geometrically
and topologically accurate approximation of the isosurface.”

Isosurface Stuffing: Fast Tetrahedral Meshing with Good Dihedral Angles

Again, although this is a geometry paper at heart, it has obvious applications to fluids and finite element simulation, so it’s definitely relevant. And allow me to editorialize for a moment and say, wow, that’s fast.

Tim Rowley and Ke-Sen Huang jointly maintain an updated list of upcoming SIGGRAPH papers as they get posted. Apparently there were 108 papers accepted this year, so odds are a healthy chunk of those will be filed under physics-based animation.

SIGGRAPH 2007 papers on the web

So far:

• A Finite Element Method for Animating Large Viscoplastic Flow
• Many-Worlds Browsing for Control of Multibody Dynamics
• Simulation of Bubbles in Foam With The Volume Control Method
• Adaptively Sampled Particle Fluids
• FastLSM: Fast Lattice Shape Matching for Robust Real-Time Deformation
• Volume Conserving Finite Element Simulation of Deformable Models
• Wrinkled Flames and Cellular Patterns
• Curl-Noise for Procedural Fluid Flow
• A Variational Approach to Eulerian Geometry Processing
• A Fast Variational Framework for Accurate Solid-Fluid Coupling
• Continuous Collision Detection for Articulated Models using Taylor Models and Temporal Culling
• TRACK: Toward Directable Thin Shells
• Isosurface Stuffing: Fast Tetrahedral Meshing with Good Dihedral Angles
• Efficient Simulation of Inextensible Cloth

 “We present a fast method for simulating, animating, and rendering lightning using adaptive grids. The “dielectric breakdown model” is an elegant algorithm for electrical pattern formation that we extend to enable animation of lightning. The simulation can be slow, particularly in 3D, because it involves solving a large Poisson problem. Losasso et al. recently proposed an octree data structure for simulating water and smoke, and we show that this discretization can be applied to the problem of lightning simulation as well. However, implementing the incomplete Cholesky conjugate gradient (ICCG) solver for this problem can be daunting, so we provide an extensive discussion of implementation issues. ICCG solvers can usually be accelerated using “Eisenstat’s trick,” but the trick cannot be directly applied to the adaptive case. Fortunately, we show that an “almost incomplete Cholesky” factorization can be computed so that Eisenstat’s trick can still be used. We then present a fast rendering method based on convolution that is competitive with Monte Carlo ray tracing but orders of magnitude faster, and we also show how to further improve the visual results using jittering.”

Fast Animation of Lightning Using an Adaptive Mesh

“The Symposium on Computer Animation (SCA) is the premier forum for innovations in the software and technology of computer animation. This annual event brings together researchers and practitioners working on all aspects of time-based phenomena. The intimate size, the single track program , and comfortable surroundings make this symposium an ideal opportunity to exchange research results and implementation experiences, and to witness some of the best research in computer animation.”
It’s collocated with SIGGRAPH this year, August 3-4, in San Diego.

SCA 2007

Having a strong personal interest in physics-based animation, I thought it would be interesting to start a blog that aids in collecting and disseminating information related to physics-based animation, taking inspiration from the GPGPU site. Since I’m starting this in March of 2007, I’m not going to bother collecting papers preceding, say, January 2007, but if you have any new papers, conferences, books or courses you would like to see noted here, please consider leaving a comment on the About page.