Issue: November 1, 2009


AUKLAND, NEW ZEALAND — While New Zealand might be known as home of visual effects giant Weta Digital, there is another large VFX entity in the country that keeps just as busy with film, commercial, television work and more.
Auckland’s PRPVFX Ltd. (www.prpvfx. com), the second largest visual effects house in the country (yes, Weta is the largest), recently provided more than 300 shots for Disney XD channel’s made-for-TV movie, Skyrunners, which follows two brothers who find a friendly UFO while out on an evening drive.
Of the 320 shots that PRPVFX supplied for this sci-fi feature, one-third were completely CG. The studio’s main shots on Skyrunners included the “dogfight” sequence, the “alien’s lair,” an alien morph, and a scene involving CG dodgeballs that will make any of us ever forced to play this violent gym game shudder. Weta Workshop, in Wellington, was hired for the alien creature design and provided the practical alien creature effects.
In the dodgeball scene, our hero Tyler is being tormented by bullies in gym class who don’t realize that a UFO ride in space has left him with super-human strength and abilities. As they whip dodgeballs at him, he is able to slow everything down, making evasive moves with cat-like agility.
“This sequence was quite involved,” explains VFX supervisor Carol Petrie, adding that PRPVFX created 3D simulations, via Autodesk 3DS Max, of all the dodgeballs. “Footage from the Phantom camera was used, so everything was slow motion. Our sims with CG dodgeballs had to match that slo-mo footage. The challenge was getting the CG dodgeballs to look the same as the real ones and matching reflections on the shiny gym floor.” PRPVFX also provided wire removal on these scenes — the young actor playing Tyler was on wires, which allowed him to move in superhuman ways.


PRPVFX artists used the practical UFO set piece as a basis for its CG model of the boys’ spaceship, built in 3DS Max. Concept art was used to create the alien UFO, which tries to shoot down the boys. According to Petrie, “The boys’ practical UFO has a glass canopy that could be removed, so when they shot the dogfight greenscreen, we took the canopy off and replaced it with a CG one in order to control reflections and the environment they were flying through.”
Another challenge on the greenscreen shoot was all the movement involved in making it look like the boys were flying the practical spacecraft. “We had tracking markers on the UFO so we could track the canopy, but a lot of the time the boys would be moving around, so we had to do hand tracking to get it to match,” explains Petrie. “It was tricky to get the canopy on and have it look exactly right. We used SynthEyes when we could but not every track will work perfectly, so we had to rely on animators to match-move by eye.”
Petrie points to quality previs created at the storyboard stage in making the dogfight sequence work smoothly. “Our on-set VFX supervisor Giles Molloy built previs scenes and had those QuickTimes on set during the shoot to make sure we were getting right angles,” she explains. “It was refined, and Giles would try a few different cameras and moves, and take it back on set and run it by the director [Ralph Hemecker] again.”


To match to concept art provided of how the producers wanted the alien hive to look, PRPVFX built it from scratch in CG using a combination of 3D modeling and 3D compositing.
“There was an underlying theme so it looked corrosive and twisted, like a yucky toxic environment,” describes Petrie. “We kept getting feedback and refining that look with producers; we were refining right up until delivery.”
She says getting the feeling of scale was biggest challenge for this sequence, which was meant to look like a humongous bug factory. “It would be like if the Titantic landed in a cave vertically. We needed to show the factory as the focal point, but there was a hive of activity spreading out from the central focus, so there were lots of depth cues added. However it was a challenge not to let any of the elements we were using betray the immense scale we were trying to convey.”


In one scene, the NSA agent who has been after the boys turns out to be an alien, and we know this because he morphs into one right before our eyes.
“We tried to get a chrysalis feeling, where the alien was breaking out of the skin,” explains Petrie, “and the challenge was to get the alien peeling off the real guy. We had one person — Stephen Donoghue— working on that entire sequence, trying things out. We didn’t want it to look too grotesque but more organic and natural. We got an interesting look that hasn’t been seen before. It’s definitely not your standard morph.”
PRPVFX’s 3D tool of choice was Autodesk 3DS Max. They even created digital versions of the aliens and boys in the software. Autodesk Combustion was used for compositing and The Foundry’s Nuke was called on to compile elements.
Petrie credits early intervention with making the project go smoothly. “Because we talked so much with producers [Richard C. Okie and Janine Dickins] and the director before hand, we understood what they wanted.”
She calls the preproduction process invaluable. Something else that helped was getting high definition QuickTimes of shots before the cut was locked so PRPVFX artists could start trying things out.
“And once we got the DP’s [Rob Marsh] proper footage we could replace it and carry on, so there was no break in the process. We try to do that with everything we work on,” she concludes.