A Data-driven Approach for Synthesizing High-resolution Animation of Fire
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Transcript of A Data-driven Approach for Synthesizing High-resolution Animation of Fire
A Data-driven Approach for Synthesizing High-resolution Animation of Fire
Syuhei SatoTakuya Morita
Yoshinori DobashiTsuyoshi Yamamoto
Hokkaido University
DigiPro '12 Proceedings of the Digital Production Symposium
Introduction
• Animators try to create the desired motions by repeating fluid simulations with different parameters until a satisfactory result is obtained.– Expensive computational cost
Relative Work
• Control the fluid simulation to create the desired motion
• Covert the low resolution into high resolution• Control the high resolution with low resolution• Combining noise into low resolution
Less realistic than those obtained by physical simulations
Motivation
• Similar flow pattern at different times and positions on different scales during animations of gaseous objects.
• Preprocessing step: database of high-resolution velocity field(2D)
• High resolution velocity field is synthesized from the low resolution with linear combination of the precomputed velocity field.
Features• The database is created by 2D fluid simulation. We use 2D
velocity fields to add small-scale detail to the 3D low-resolution velocity field. This results in a significant reduction in computational costs for both precomputation and the run-time process.
• Using our synthesis method recursively, animations can ideally be synthesized with arbitrarily high resolution.
• The method is highly suitable for parallel computation. The low-resolution velocity field is subdivided into small blocks
and the high-resolution velocity field can be synthesized in parallel for each block.
Overview
Database Construction
• Constructed by 2D fluid simulation– Divide into nb X nb blocks– Apply PCA(principal component analysis) to get
PVF(principal velocity fields)• Cannot synthesize detailed turbulence in 3D
simulation if such turbulence is not included in 2D simulation.
Synthesizing a High-resolution 3D Velocity field
• A low resolution 3D fluid simulation is executed and converted into high resolution by PVF.
• Each output velocity is generated slice by slice and each slice is divided into blocks.– The blocks overlap in order to reduce the
discontinuity.
Converter
Compute the weight for PVF• Apply the above process three times: xyz – Horizontal component in 2D: u is used for horizontal
components in 3D: x, y– Vertical component in 2D:v is used for vertical components
in 3D: z• Solve three minimization problems
Recursive Synthesis
• The method fails when the resolution ratio is too high. From the experience, the ratio should less than 4
• Solution: vl(input) is converted to v1, then v1 is converted to v2…..
Results