In this paper we describe how to simulate geometrically complex, interactive, physically-based, volumetric, dynamic deformation models with negligible main CPU costs. This is achieved using a Dynamic Response Texture, or DyRT, that can be mapped onto any conventional animation as an optional rendering stage using commodity graphics hardware. The DyRT simulation process employs precomputed modal vibration models excited by rigid body motions. We present several examples, with an emphasis on bone-based character animation for interactive applications.

Animations for which sound effects were automatically added by our system, demonstrated in the accompanying video. (a) A real wok in which a pebble is thrown; the pebble rattles around the wok and comes to rest after wobbling. (b) A simulation of a pebble thrown in wok, with all sound effects automatically generated. (c) A ball rolling back and forth on a ribbed surface. (d) Interaction with a sonified object. We describe algorithms for real-time synthesis of realistic sound effects for interactive simulations (e.g., games) and animation. These sound effects are produced automatically, from 3D models using dynamic simulation and user interaction. We develop algorithms that are efficient, physicallybased, and can be controlled by users in natural ways. We develop effective techniques for producing high quality continuous contact sounds from dynamic simulations running at video rates which are slow relative to audio synthesis. We accomplish this using modal models driven by contact forces modeled at audio rates, which are much higher than the graphics frame rate. The contact forces can be computed from simulations or can be custom designed. We demonstrate the effectiveness with complex realistic simulations.

and compelling sounds that correspond to the motions of rigid objects. By numerically precomputing the shape and frequencies of an object's deformation modes, audio can be synthesized interactively directly from the force data generated by a standard rigid-body simulation. Using sparse-matrix eigen-decomposition methods, the deformation modes can be computed efficiently even for large meshes. This approach allows us to accurately model the sounds generated by arbitrarily shaped objects based only on a geometric description of the objects and a handful of material parameters. We validate our method by comparing results from a simulated set of wind chimes to audio measurements taken from a real set.

A new paradigm for rigid body simulation is presented and analyzed. Current techniques for rigid body simulation run slowly on scenes with many bodies in close proximity. Each time two bodies collide or make or break a static contact, the simulator must interrupt the numerical integration of velocities and accelerations. Even for simple scenes, the number of discontinuities per frame time can rise to the millions. An efficient optimization-based animation (OBA) algorithm is presented which can simulate scenes with many convex threedimensional bodies settling into stacks and other “crowded” arrangements. This algorithm simulates Newtonian (second order) physics and Coulomb friction, and it uses quadratic programming (QP) to calculate new positions, momenta, and accelerations strictly at frame times. The extremely small integration steps inherent to traditional simulation techniques are avoided. Contact points are synchronized at the end of each frame. Resolving contacts with friction is known to be a difficult problem. Analytic force calculation can have ambiguous or non-existing solutions. Purely impulsive techniques avoid these ambiguous cases, but still require an excessive and computationally expensive number of updates in the case of

Simulating sounds produced by realistic vibrating objects is challenging because sound radiation involves complex diffraction and interreflection effects that are very perceptible and important. These wave phenomena are well understood, but have been largely ignored in computer graphics due to the high cost and complexity of computing them at audio rates.

We describe and test methods to construct modal resonance models for solid objects, suitable for the real-time synthesis of soundeffects in simulation and animation. Measurements on typical everyday objects such as a metal vase or a bowl result in several hundred modes, of which only a small fraction is perceptually relevant. We have proposed several heuristics, inspired by psycho acoustical data, to select the modes by perceptual relevance and to order them so that one can increase the quality by adding more modes, at the price of additional computational complexity (progressive synthesis). The resulting synthetic sounds are tested on human subjects in order to determine the quality of the sounds relative to the target sound which they are designed to approximate. The resulting data is used to verify and tune the mode selection methodologies, and to increase our understanding of what determines the subjective quality of a synthetic sound effect. 1.

This article describes banded waveguides, a way of synthesizing sounds made by solid objects and an alternative method for treating two- and three-dimensional objects. It belongs to the synthesis algorithms known as physical models, and in particular, it is a departure from waveguide synthesis. Physical modeling of musical instruments is a synthesis technique that is well established in computer music. Physical models are historically related to computationally expensive algorithms (Ruiz 1969) but have become more efficient with faster methods such as waveguide synthesis (Smith 2003). Digital waveguide models provide discretetime models of distributed media such as vibrating strings, bores, horns, and plates. We begin by outlining related synthesis methods with emphasis on traditional waveguide synthesis, which motivated the creation of this new structure. To simulate sustained and transient excitations such as striking, bowing, and rubbing, different excitation models are also proposed in this article. Instruments that have been modeled

An example of aerodynamic sound generated by swinging swords. Sound wave (below) is computed based on the motion and shape of the swords. The motion blur is artificially added to visualize the motion of the swords. In computer graphics, most research focuses on creating images. However, there has been much recent work on the automatic generation of sound linked to objects in motion and the relative positions of receivers and sound sources. This paper proposes a new method for creating one type of sound called aerodynamic sound. Examples of aerodynamic sound include sound generated by swinging swords or by wind blowing. A major source of aerodynamic sound is vortices generated in fluids such as air. First, we propose a method for creating sound textures for aerodynamic sound by making use of computational fluid dynamics. Next, we propose a method using the sound textures for real-time rendering of aerodynamic sound according to the motion of objects or wind velocity. CR Categories: I.3.7 [Computer Graphics]: Three-Dimensional

This thesis proposes banded waveguide synthesis as an approach to real-time sound synthesis based on the underlying physics. So far three main approaches have been widely used: digital waveguide synthesis, modal synthesis and finite element methods. Digital waveguide synthesis is efficient and realistic and captures the complete dynamics of the underlying physics but is restricted to instruments that are well-described by the one-dimensional string equation. Modal synthesis is efficient and realistic yet abandons complete dynamical description and hence cannot used for certain types of performance interactions like bowing. Finite element methods are realistic and capture the behavior of the constituent physical equations but on current commodity hardware does not perform in real-time. Banded waveguides offer efficient simulations for cases for which modal synthesis is appropriate but traditional digital waveguide synthesis is not applicable. The key realization is that the dynamic behavior of traveling waves, which is being used in waveg-uide synthesis, can be applied to individual modes and that the efficient computational

Figure 1: Crash! Our physically based sound renderings of thin shells produce characteristic “crashing ” and “rumbling ” sounds when animated using rigid body dynamics. We synthesize nonlinear modal vibrations using an efficient reduced-order dynamics model that captures important nonlinear mode coupling. High-resolution sound field approximations are generated using far-field acoustic transfer (FFAT) maps, which are precomputed using efficient fast Helmholtz multipole methods, and provide cheap evaluation of detailed low- to high-frequency acoustic transfer functions for realistic sound rendering. We propose a procedural method for synthesizing realistic sounds due to nonlinear thin-shell vibrations. We use linear modal analysis to generate a small-deformation displacement basis, then couple the modes together using nonlinear thin-shell forces. To enable audiorate time-stepping of mode amplitudes with mesh-independent cost, we propose a reduced-order dynamics model based on a thin-shell cubature scheme. Limitations such as mode locking and pitch glide are addressed. To support fast evaluation of mid-frequency modebased sound radiation for detailed meshes, we propose far-field acoustic transfer maps (FFAT maps) which can be precomputed using state-of-the-art fast Helmholtz multipole methods. Familiar examples are presented including rumbling trash cans and plastic bottles, crashing cymbals, and noisy sheet metal objects, each with increased richness over linear modal sound models.