Dust to dust

04Mar09

Several different ways to make a dust.

quicktime movie

We need 3dsmax, vray, ae, physx, fumefx, krakatoa, a lot of time and disk space.

0. Simulation with PhysX.

Build a house from simple non-intersected blocks (bricks, ceiling, glass, roof tiling etc.).

Roof frames and other concave objects must be joined into groups.

Make all objects, except the floor, Dynamic RigidBodies, assign them different weights. Set initial speed and big weight for the demolition spheres.

Add all physical objects to the simulation and simulate for 250 frames with Auto Key button enabled. Render with Vray.

Make some hidden noised geometry behind pre-broken glass and push them away at the right moment.

1. Sprites dust with Particle Flow.

Make the sprites system – tons of camera oriented square particles with transparent texture.

Sprites should be born on the hi-speed moving objects and fly with the same direction. Also they should be decelerating and dissolving with age.

Stick a huge amount of particles to all the scene objects, and spawn the sprites from them when the parent particles will have certain velocity or acceleration.

The acceleration sprites will be born at the impact moment, like some clouds beating from parent objects.

Velocity sprites will escort the most active parent objects like a cloudy trails.

Make the dust material for the sprites with a radial gradient mixed with Smoke map for a opacity texture, dissolved with Particle Age.

We should have a lot of particles for an intersection artefacts minimisation, growing with age and then dying.

Make the Drag force for the sprites air decceleration, assign a Matte material for the geometry an render with Scanline.

2. Debris with Particle Flow.

Debris should be made from geometry particles (Tetra). They must be randomly scaled, and rotating.

Add the floor Deflector and a Gravity, kill the Drag.

Render with scanline.

3. Ground impacts dust with Vray, AE, Fumefx.

We need some kind of Realflow wetmap for a ground impacts dust.

First, render a ground Vraydirt map or any other occlusion texture from the top view. Hide for camera (not for render) all other objects.

Blend a couple of rendered texture copies with the Difference, shifted the top layer for one frame in AfterEffects, then precompose.

Blend about 10 copies of this Comp with Add or Screen and Blur them, shifting eath layer for one frame.

So we have the texture, white at the object’s movements near the ground. The texture should be a smoke emitter in the FumeFX.

Set the small Buoyancy and huge Diffusion for a more dusty look.

Render the smoke, lighted with direct light, placed at the same location as the Vraysun.

Add the blue light across the sun, for a more dramatic render.

Turn on the Fluid map before the FumeFX simulation for more detailed dust.

Don’t forget to turn on the Fluid map in Exporting channels, and add some Noise or Smoke textures in appropriate slots.

4. Turbulent dust with Particle Flow, FumeFX and Krakatoa.

Open the velocity Sprites scene and make the FumeFX smoke emitters from all of the particles.

Simulate smoke with FumeFX and save the cache. We need the Velocity channel in the Exporting channels enabled before the simulation.

Make new Pflow particle system, producing 5 millions of particles, that should be born on the scene objects with small random offset inside (to minimise the moire effects)

The FumeFX Follow operator will control particles speed, all we need is picking the FumeFX container wihtin the operator.

Cache all the animation to disk with Save Particles To File Sequence routine in Krakatoa GUI. The cache will take about 20 Gb of disk space.

This pass is very cool, but we need a geomerty matte for the compositing.

So make the Named Selection Set with all the scene geometry inside and point it as Matte Object in Krakatoa GUI.

Push the geomerty outside a little for assured particle coverage.

That is all.

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