The arrival of destructive beings on the west coast of the U.S. in Battle: Los Angeles is heralded by a unique take on alien spaceship technology: mysterious smoke rings. The rings, used heavily in the film’s marketing, were created by Cinesite and from their visual effects supe Ben Shepherd.
fxg: So one of the key images at the beginning of the film are these enormous clouds forming over Santa Monica. What exactly are they?
Shepherd: Well it turned out to be one of the major design elements in the film. The aliens arrive in these mysterious meteorites which break off a little bit as they fly through the sky. When they get within about 100 yards of impact, they fire some sort of mysterious retro breaking rocket, which forms this huge mushroom cloud and smoke ring.
fxg: How did that look come about?
Shepherd: We were out shooting in Louisiania for a later sequence, where there’s almost like a Magnificent Seven last stand and they’re trying to laser designate the alien command and control center, and call in an airstrike. In that whole section, there were lots of practical effects going off that we enhanced or augmented. You’ll see a shot of a missile coming in and blowing up the antenna – there was a big huge practical fireball effect, which we augmented with shockwaves and a whole CG ground that shakes.
Well, Michelle Rodriguez who plays one of the soldiers, was looking at one of the explosions and pointed it out, so we all looked up and there was this 20 meter wide smoke ring just sort of gently floating away after one of the fireball effects. Everett Burrell (the film’s overall visual effects supervisor) turned around to me and said, ‘Hey, cool man, but if you made that in CG no one would believe you would they?’ At which point Jonathan Liebesman (the director) said, ‘Cool, that’s great! I want that in my movie!’ And that was the birth of the smoke ring that came off the meteorite.
fxg: Was there any thought in doing them as practical explosions and layering them in?
Shepherd: Well, Jonathan had also laid down a challenge that he could spot any CG smoke, so not only did we have to make the impossible, we had that challenge as well. But we needed to control them, so we had to get the right look of the meteorites and the look of the smoke rings and the meteorites finally smash into water and produce big splashes almost like depth charges in the sea.
fxg: How did you end up realizing the rings in CG?
Shepherd: We basically used Maya Fluids and proprietary fluid renderer and RenderMan. We also had our new smoke system, csSmoke. There’s a couple of shots where they look from the helicopter down into the on-going battle in Santa Monica. The aliens use this smokescreen as a defence mechanism, so we see CG explosions, CG tanks and CG crowds and smoke. You get subtle glimpses of the ongoing battle as the explosions push the mist away with shockwaves. And there’s a whole sequence where our heroes are under attack in the helicopters and out of the window there’s flack going off and they fly through the smoke rings.
fxg: Can you tell me more about the techniques you used to complete the rings?
Shepherd: Since Maya Fluids is now multi-threaded and now that you’ve got these spanking 16 core machines, you can really do big 3D fluid simulations. However, Maya Fluids is a very world-oriented system, so if you want to make a smoke ring it will always float up, but we had to make something that was stationary. The rings really look more like a jellyfish. It basically goes ‘bang’, but there’s no fire. It just sits there and dissipates.
The 3D smoke rings were pretty much out of the box without too much fixing in compositing. We just had to tidy some of the hold-outs and added extra phosphorous falling elements and flash lens flares.
All images copyright © Columbia Pictures.