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Advected textures

Advected textures. Fabrice Neyret EVASION - GRAVIR / IMAG - INRIA Grenoble, France. Purpose: amplifying fluid simulation. Purpose: amplifying fluid simulation. Why not simply increase resolution ?. Cost: N log(N) / time step with N=1000^3 Storage

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Advected textures

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  1. Advected textures Fabrice Neyret EVASION - GRAVIR / IMAG - INRIA Grenoble, France

  2. Purpose: amplifying fluid simulation

  3. Purpose: amplifying fluid simulation

  4. Why not simply increase resolution ? • Cost: N log(N) / time step with N=1000^3 • Storage • Problems with CFD for CG [Lamorlette&Foster 02] • Unknown small scale phenomena vsartist desires + phenomenological knowledge

  5. Why not simply increase resolution ? • Cost: N log(N) /timestep with N=1000^3 • Storage • Problems with CFD for CG [Lamorlette&Foster 02] • Unknown small scale phenomena vsartist desires + phenomenological knowledge

  6. Why not simply increase resolution ? • Cost: N log(N) / timestep with N=1000^3 • Storage • Problems with CFD for CG [Lamorlette&Foster 02] • Unknown small scale phenomena vsartist desires + phenomenological knowledge

  7. Why not simply increase resolution ? • Cost: N log(N) / timestep with N=1000^3 • Storage • Problems with CFD for CG [Lamorlette&Foster 02] • Unknown small scale phenomena vsartist desires + phenomenological knowledge

  8. Advecting textures • = Advecting u,v [Max&Becker 96, Stam 99] • Regeneration • blending 3 dephased textures (illusion of motion) • latency = life duration

  9. Problems with texture advection 1 2 3 • Choosing the latency • Blending textures • Sub-animation

  10. Problems with texture advection 1 2 3 • Choosing the latency • Blending textures • Sub-animation

  11. Problems with texture advection 1 2 3 • Choosing the latency • Blending textures • ghosting effects • Sub-animation

  12. Problems with texture advection 1 2 3 • Choosing the latency • Blending textures • Sub-animation

  13. Problems with texture advection 1 2 3 • Choosing the latency • Blending textures • Sub-animation

  14. 1. Advecting textures • A latency value is ok for a range of velocities (V) • bad motion illusion if V < • texture stretching if V >

  15. 1. Advecting textures • Adapting latency locally • Layers of given latency + masks • Local criterion • cumulated deform = particle integral of |e| • Target deform d*

  16. 1. Advecting textures • Adapting latency locally • Layers of given latency + masks Layer 1: lat1 Layer 2: lat2 (>lat1) Layer 3: lat3 (>lat2) • Local criterion • cumulated deform = particle integral of |e| • Target deform d*

  17. 12 3 1. Advecting textures • Adapting latency locally • Layers of given latency + masks • Local criterion • cumulated deform = particle integral of |e| • Target deform d*

  18. 2. Blending textures • Image textures • Procedural textures

  19. 2. Blending textures: image textures • What to do ? (morphing ?)

  20. Our solution: 2. Blending textures: procedural textures

  21. 3. Sub-animation • Flownoise [Perlin&Neyret 01]

  22. 3. Sub-animation • Flownoise for sub-scales • rotations  vorticity spectrum • Kolmogorov cascade

  23. 3. Sub-animation • Flownoise for sub-scales • rotations  vorticity spectrum < > • Kolmogorov cascade

  24. E CFD sub-grid microscale k = 2p/l k0 ke 3. Sub-animation • Flownoise for sub-scales • rotations  vorticity spectrum < > • Kolmogorov cascade

  25. < > < > 3. Sub-animation • Vorticity energy transfer through scales • distribution law for ( power law ) • only needs to scale it ( estimate ) • Our case: • heterogeneous fluid ( locality -> no Fourier ) • not at equilibrium ( transfer delay -> time ) • user control • relaxation

  26. < > < > 3. Sub-animation • Vorticity energy transfer through scales • distribution law for ( power law ) • only needs to scale it ( estimate ) • Our case: • heterogeneous fluid ( locality -> no Fourier ) • not at equilibrium ( transfer delay -> time ) • user control • relaxation (user-defined parametersbkandgk )

  27. Results

  28. Conclusion • Mixing lo-res CFD and hi-res animated texture: • A model efficient & controllable • Future work: • 3D applications: detailed clouds & avalanches • Better flownoise control • Manage empty space • Hardware procedural shader

  29. Advected textures Fabrice Neyret EVASION - GRAVIR / IMAG - INRIA (Grenoble, France)

  30. Sub-animation parameters • parametersbkandgk: • small b: reactive high b: inertial • small g: viscous high g: light

  31. 1. Advecting textures

  32. 3D

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