Real-time Generation of CG and Sound of Liquid with Bubblefharhad/ganbatte/siggraph...3 Automatic...
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Real-time Generation of CG and Sound of Liquid with Bubble Masataka Imura ∗ Yoshinobu Nakano Yoshihiro Yasumuro Yoshitsugu Manabe Kunihiro Chihara Graduate School Information Science, Nara Institute of Science and Technology 1 Introduction Recently, we can render real-time CG of liquid which shows various phenomena by global lighting and physical simulation according to the improvement of the computing power. However, the effect sound for real-time CG of liquid should be made corresponding to all the behavior of the liquid beforehand. Therefore, it is difficult for high reproducibility to be made for all sounds by hand. In liquid, the sound is generated according to the change of the radius of the moving bubble. Therefore, making the effect sound of liquid should consider the movement of bubbles. In this paper, we propose the technique for enhancing Smoothed Particle Hydrodynamics(SPH), expressing the liquid with bubbles by introducing the particles that compose the liquid and the gas. Moreover, the technique for outputting the effect sound by syn- chronizing with rendering of CG is proposed. This technique dis- tinguishes the number of bubbles spatially generated by using the proximity-area search lattice of SPH. In addition, this technique can automatically generate the effect sound for real-time CG of the liq- uid by obtaining the characteristic frequency from the bubble size. The proposal technique enables to generate animation and the effect sound of the liquid with bubbles in real-time. 2 Enhancing Smoothed Particle Hydrody- namics Figure 1 shows the block diagram of the proposed system. The system can be divided into computation fluid dynamics simulation module, graphics rendering module and sound rendering module. To make appropriate sound from physical simulation of liquids, the movement of bubbles, which are main sources of the sound, must be integrated into the simulation. We enhance Smoothed Particle Hydrodynamics, one of the particle-based fluid simulation meth- ods, to treat two phases: gas and liquid. In SPH, the Navier-Stokes equation is discretized into particle-particle interaction. In the en- hanced SPH, there are interaction between gas-liquid particles and liquid-liquid particles, but no interaction between gas-gas particles. Physical Simulator Position of Particles Sound Rendering Unit Bubble (List, Radius, Position) Graphic Rendering Unit Sound Judgment Model of Generation Model of Explosion Wave Selector Frequency Modulation Output Module (OpenAL) ♪ Wave Select Flag Radius Wave Frequency Marching Cubes Shadow curved surface is generated. Shader that considers bubbles Surface Rendering. Enhanced SPH To treat two kinds of particles. The frequency is calculated from the radius of the bubble. Effect Sound is generated ! System System System System Table of Waves The position of liquid and air particles is calculated. The parameter of the bubble is calculated by clustering of air particle. Generation and explosion of bubbles are judged. The shape of waves is selected. radius frequency Rendering Shadow Curved Surface Figure 1: Proposed System ∗ e-mail: [email protected] 3 Automatic Generation of Sound of Liquid To find the position and size of bubbles in liquid, we use clustering of gas particles. For clustering, first we map the gas particles into regular lattice, then merge neighboring grids which contain gas par- ticles. The position of a certain bubble is the center of gravity of the particles which consist of one bubble and the radius of the bubble is the maximum distance between particles in the bubble. The po- sitions of bubbles are tracked frame by frame, then the generation and extinction of bubbles, which are the event accompanied with sound, are detected. Figure 2 shows the typical result of cluster- ing of gas particles. The particles which belong to the same cluster have the same color. Figure 2: Result of Clustering The typical sound of bubble generation and extinction are recorded beforehand and are used as sound source. However, the principal frequency of the liquid sound depends on the size of the bubble. In the proposed system, the appropriate sound source is selected based on the event type (generation or extinction), then the frequency of the selected sound source is modulated based on the bubble radius. After modulated, the sound is outputted using three-dimensional sound generation system. 4 Result The prototype system was constructed with OpenGL for graphics rendering and OpenAL for sound rendering on Intel Core2 Duo PC. We used 6750 liquid particles and 1000 gas particles. Figure 3 shows the typical result of the generation of graphics and sounds. We can render the proper graphics with bubbles inside the liquid and the sound is added to the animation. The speed of calculation and rendering is about 15 frames per second. Average Delay time : 15 ms Average FPS : 15 fps Figure 3: Result
Transcript of Real-time Generation of CG and Sound of Liquid with Bubblefharhad/ganbatte/siggraph...3 Automatic...
Real-time Generation of CG and Sound of Liquid with Bubble
Masataka Imura∗ Yoshinobu Nakano Yoshihiro Yasumuro Yoshitsugu Manabe Kunihiro Chihara
Graduate School Information Science, Nara Institute of Science and Technology
1 Introduction
Recently, we can render real-time CG of liquid which shows variousphenomena by global lighting and physical simulation accordingto the improvement of the computing power. However, the effectsound for real-time CG of liquid should be made corresponding toall the behavior of the liquid beforehand. Therefore, it is difficultfor high reproducibility to be made for all sounds by hand. In liquid,the sound is generated according to the change of the radius of themoving bubble. Therefore, making the effect sound of liquid shouldconsider the movement of bubbles.
In this paper, we propose the technique for enhancing SmoothedParticle Hydrodynamics(SPH), expressing the liquid with bubblesby introducing the particles that compose the liquid and the gas.Moreover, the technique for outputting the effect sound by syn-chronizing with rendering of CG is proposed. This technique dis-tinguishes the number of bubbles spatially generated by using theproximity-area search lattice of SPH. In addition, this technique canautomatically generate the effect sound for real-time CG of the liq-uid by obtaining the characteristic frequency from the bubble size.The proposal technique enables to generate animation and the effectsound of the liquid with bubbles in real-time.
2 Enhancing Smoothed Particle Hydrody-namics
Figure 1 shows the block diagram of the proposed system. Thesystem can be divided into computation fluid dynamics simulationmodule, graphics rendering module and sound rendering module.
To make appropriate sound from physical simulation of liquids, themovement of bubbles, which are main sources of the sound, mustbe integrated into the simulation. We enhance Smoothed ParticleHydrodynamics, one of the particle-based fluid simulation meth-ods, to treat two phases: gas and liquid. In SPH, the Navier-Stokesequation is discretized into particle-particle interaction. In the en-hanced SPH, there are interaction between gas-liquid particles andliquid-liquid particles, but no interaction between gas-gas particles.
Physical Simulator
Position of Particles
Sound Rendering Unit
Bubble (List, Radius, Position)
Graphic Rendering Unit
波形テーブル波形テーブル Sound Judgment
Model of Generation
Model of Explosion
Wave Selector
Frequency Modulation
OutputModule
(OpenAL)
♪♪♪♪
Wave
Select
Flag
Radius
Wave
Frequency
Marching CubesShadow curved surface is generated.
Shader that considers bubblesSurface Rendering.
Enhanced SPHTo treat two kinds of particles.
The frequency is calculated from the radius of the bubble.
Effect Soundis generated !
SystemSystemSystemSystem
Table of Waves
The position of liquid and air particles is calculated.
The parameter of the bubble is calculated by clustering of air particle.
Generation and explosion of bubbles are judged.The shape of waves is
selected.
radiusfrequency
α＝Rendering
Shadow Curved Surface
Figure 1: Proposed System
∗e-mail: [email protected]
3 Automatic Generation of Sound of Liquid
To find the position and size of bubbles in liquid, we use clusteringof gas particles. For clustering, first we map the gas particles intoregular lattice, then merge neighboring grids which contain gas par-ticles. The position of a certain bubble is the center of gravity of theparticles which consist of one bubble and the radius of the bubbleis the maximum distance between particles in the bubble. The po-sitions of bubbles are tracked frame by frame, then the generationand extinction of bubbles, which are the event accompanied withsound, are detected. Figure 2 shows the typical result of cluster-ing of gas particles. The particles which belong to the same clusterhave the same color.
Figure 2: Result of Clustering
The typical sound of bubble generation and extinction are recordedbeforehand and are used as sound source. However, the principalfrequency of the liquid sound depends on the size of the bubble. Inthe proposed system, the appropriate sound source is selected basedon the event type (generation or extinction), then the frequency ofthe selected sound source is modulated based on the bubble radius.After modulated, the sound is outputted using three-dimensionalsound generation system.
4 Result
The prototype system was constructed with OpenGL for graphicsrendering and OpenAL for sound rendering on Intel Core2 DuoPC. We used 6750 liquid particles and 1000 gas particles. Figure 3shows the typical result of the generation of graphics and sounds.We can render the proper graphics with bubbles inside the liquidand the sound is added to the animation. The speed of calculationand rendering is about 15 frames per second.
Average Delay time : 15 ms Average FPS : 15 fps
Figure 3: Result
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