A Data-driven Approach for
Synthesizing High-resolution
Animation of Fire
Syuhei Sato
Takuya Morita
Yoshinori Dobashi
Tsuyoshi 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 highresolution 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 lowresolution 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