STEVE'S CATCH DUST & DIRT FX BREAKDOWN
Proximity Based Activation
Vellum grains are all inactive initially (i@stopped=3). As the Collider (Ship) gets within a user defined distance, the grains activate.
Aside from slight performance gains, this helps the tub of grains keep its shape and not crumble away especially around the borders.
Red means it's active. This clip is just a visualization. The activation actually happens together in the sim.
A stripped down version of the ship is brought in as a volume collision (Converted into a VDB in SOPs).
A ground plane was also brought in so the grains don't fall into oblivion.
Smoke Sim using Grains as a source
The simulated grains are then used as a source for the smoke. Only grains above a certain speed and will be used as a source for the smoke sim.
Using the Volume Rasterize Attributes node, attributes from the grains simulation (v, pscale) and additional attributes (density) are used to create volumes. These volumes are then sourced into the smoke sim.
Effects Out of Houdini
The finalized effects are then rendered separately using mantra to be comped in Nuke.
The reason it was not rendered all together was because there was no way to import volumes into Maya (where everything else is rendered) at the time.
The lighting setup from Maya had to be replicated and the necessary environment geometry was used to create the shadows.
The Effects were comped in Nuke by the brilliant Lighting, Compositing and Rendering team.
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