Simulation and Fabrication

Summary: We introduce a new advection scheme for fluid animation. Our main contribution is the use of long-term temporal changes in pressure to extend the commonly used semi-Lagrangian scheme further back along the time axis. Our algorithm starts by tracing sample points along a trajectory following the velocity field backwards in time for many steps. During this backtracing process, the pressure gradient along the path is integrated to correct the velocity of the current time step. We show that our method effectively suppresses numerical diffusion, retains small-scale vorticity, and provides better long-term kinetic energy preservation.

Author(s): Takahiro Sato, The University of Tokyo
Christopher Batty, University of Waterloo
Takeo Igarashi, The University of Tokyo
Ryoichi Ando, National Institute of Informatics

Speaker(s): Takahiro Sato, The University of Tokyo

Summary: The computational cost of physically-based fluid simulation for generating realistic animations is expensive. Therefore, it takes a long time for an animator to create the desired animation. To reduce such costs, several methods have been developed that employ an approach in which turbulence is synthesized as a post process. Since, with this approach, global motion can be obtained using low-resolution fluid simulation, realistic animations with the desired behavior can be created at low cost. In the field of image editing, style transfer methods, which can efficiently achieve the desired stylization by transferring features of an example image to a user-specified image, have been proposed. We combine these concepts and present a novel style transfer method for turbulence by reusing the existing fluid animations. Our system allows the user to transfer turbulent motion from one flow field to other flow fields. We do this by extending example-based image synthesis methods to the flow field: a patch-based synthesis and an optimization-based texture synthesis. Our method is designed such that the resulting flow fields satisfy the incompressibility condition. Our method can intuitively and easily create high-resolution fluid animations with the desired turbulent motion.

Author(s): Syuhei Sato, UEI Research
Yoshinori Dobashi, UEI Research, Hokkaido University
Tomoyuki Nishita, UEI Research, Hiroshima Shudo University

Speaker(s): Syuhei Sato, UEI Research (DWANGO Co., ltd.)

Summary: In this paper, we present a method for computational design and fabrication of hanging structures. A hanging structure is composed of a series of linked rods, and forms a specific shape under gravity. Given a user-specified shape, our algorithm automatically optimizes the configuration of the rods, so that the resulting structure can resemble the target shape. The optimization is achieved by a two-phase iterative steps, including shape simulation and configuration optimization. Based on our structure designing algorithm, we fabricate the structure with a 3D printer. Hollow cavities and metal materials are embedded into plastic rods to finely adjust their weight. A set of simulation and fabrication results demonstrate the ability of our method to materialize various target shapes.

Author(s): Boyu Song, Peking University
Jie Feng, Peking University
Bingfeng Zhou, Peking University

Speaker(s): Boyu Song, Institute of Computer Science & Technology of Peking University