Final Render
Tornado Effects R&D | Houdini from Yanni Fong on Vimeo.
Reference
Particles Sourcing
The particles look like a boring spiral, so I use some VEX code to make it more organic, mapping circle to spiral.
Original | Modified | Reference (Fibonacci sequence in nature) |
VEX Code used |
Volume Sourcing
I converted the particles to volume, and then run a simple pyro simulation to get more complex and detailed pre-roll volume.
Particles | Simulated ( As a pre-roll) |
Dopnet (for pre-roll volume)
Use density as the control field for gas disturbance. Stronger disturbance at where it has lower density. | Disturb velocity field to get a nicer look. |
Simulation
Dopnet for main pyro simulation |
Rim Detail
The tornado constantly drawing air into its center and the cloud at the edge are changing constantly. Therefore, I animated a turbulence noise moving in y-axis and use VEX to map it into a spiral-like noise. Then, use distance from the tornado center to mask out the unwanted part.
Turbulence noise deformed by point VOP | Volume applied noise, masked out according to the point’s distance to center |
Point VOP used to deform the noise, offsetting the original position in the direction along the tangent.
Observation about Shadow
My first few attempts looks very flat lighting-wise because the volume is not ‘deep’ enough. The tornado has more depth than what its look like. By scaling up y-axis, of the volume, it gains more depth and the lights immediately cast darker shadow. Changing the lighting condition does not help to define the cloud shape.
Flat cloud | More defined cloud shape |