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Orbaz Technologies Forum Index » Orbaz News » Particle Flow and Particle Flow Tools on the small screen
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Particle Flow and Particle Flow Tools on the small screen
PostPosted: Sat Nov 18, 2006 10:51 am Reply with quote
Oleg
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Joined: 26 Sep 2004
Posts: 5701
Location: The Hundredth Town, USA




SciFi is a favorite domain for Particle Flow and Particle Flow Tools. Sam Khorshid, FX artist and CG Animator at Blur, explains how they were used in the production of The Triangle a Sci Fi mini series:

There were over 9 hundred visual effects shots, including explosions, water dynamics, storms, and melting characters. Pretty much every complex effect they can throw at you.

Particle Flow and the accompanying PFlowTools Boxes were used extensively to create several of these effects. I will go over 2 of my favorites, the whaling ship explosion, and the melting sailor.

The idea behind melting sailor effect: our poor sailor found himself on the edge of a time space phenomenon, which liquefies his flesh and sends it swirling off. Mmm... sounds goopey.

We had a small amount of RnD time for this effect, so I started by first creating a generic melting set up. Using Particle Flow, a generic character mesh was covered in a dense surface of particles; the particle surface would represent the sailor’s skin. Using different selection methods, sections of the particle skin would slide of the mass, controlled by different forces, and collisions. Pwrapper (blob mesh tool from www.3daliens.com) was used to envelope the particles, which helps create that fluid feel of the flesh as it melts away.

Example 1: meltyman.mov (1.1MB)______________Example 2: meltskin.mov (0.9MB)




We had a film plate of the actor screaming at the camera, there was a lot of camera movement, so we stabilized the footage in Digital Fusion, creating a plate much easier to match our effect too.

Example 3: Live Action (0.2MB)_________________Example 4: Stable Footage (0.2MB)




Digital scans of the actor were taken, outputting a high resolution 3d mesh of the sailor. From that mesh, muscle layers and an underlying skeleton were built. These would be revealed as the flesh melts away. The sailor mesh’s then had to be rigged and animated to match the movement of the film plate.

Once a generic set up was working and approved, the effect could be applied to the shot.

The Skin and muscle layers of the sailor had the particle melt effect applied.
Once areas of melting were agreed upon, we used Pftools box 3 to cache these sections, giving us the ability to separate out section’s of the effect, and make real time updates under director supervision.

Using Pwrapper’s integration with Particle Flow’s event based nature, we were able to change the consistency of the sailors flesh depending on what state it was in. From the elastic firmness of skin, to the fluid viscosity of honey.

The shader was also controlled on an event basis. When the skin is attached to the face a camera mapped shader was used to project the film plate onto the mesh, as it peeled off it transitioned into a subsurface shader, letting background light pass threw the melting skin, helping integrate the overall effect.

Everything was rendered to layers using Brazil Rs, and composited together by Robin Graham using a whole lot of voodoo magic in Digital Fusion.

Example 5: Melt Final (6.7MB)




Now to the whaling ship destruction: underwater activity lifts the ship and tears it in two.

This sequence was especially tough, as we had to match the ocean and ship plates that precede the destruction.

Example 6:




We created a rough animatic of the sequence, and used this to figure out how much ocean we would need to create, and what kind of interaction we would need. With Siti Sini’s Dreamscape we were able to create a general sea surfaces and swell patterns. By using an adaptive mesh (which allows for less mesh density based on camera distance), we were able to apply higher frequency waves on the surface, but keep the details only in the foreground, making everything more manageable with out compromising quality (well at least not too much).

We were unable to emit particles from the adaptive sea surface. So we created low-resolution proxy surfaces, using displacement maps created from the adaptive sea surface. These were then used to emit particles, and gain the velocity/motion inherited information to create more realistic spray and splash movements.

Example 7: ocean.mov (0.5MB)______________Example 8: mist.mov (0.5MB)




Large scale splash interaction with the boat were created in Real Flow 3.0 but due to time constraints we were unable to get the simulation looking correct. We instead created a library of smaller generic splash elements in Glu 3d, and then set them up as Particle Flow birth events.

Now that we had the sims in PF we were able to do secondary splash elements based on spawns and boat collisions. The advantage to this method, we were able to quickly alter the look of the splash interaction without having to recalculate the whole thing.

Example 9: Triangle Whaling (6.7MB)




It was rendered out in Vray and comped by Ben Grosmann in After Effects.


The Triangle a Sci Fi mini series
Produced by Kelly van Horn, Volker Engel and Marc Weigert
Executive Producers Bryan Singer and Dean Devlin
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Particle Flow and Particle Flow Tools on the small screen
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