London-based Peerless Camera Co. and Digiscope discuss creating the signature "push" effect and more for Push.
Not unlike TV's Heroes or last year's Jumper, Push (from Summit Ent.) involves a group of young people who were born with psychic powers. Some can see the future, others can see the history of an object and some can temporarily change the shape of things, wipe away memory or put thoughts into other people's heads. And some are able to move people and objects via telekinesis -- which leads to highly unusual confrontations.
Originally, director Paul McGuigan's intent was to use practical effects as much as possible, and minimize the use of visual effects. But as it often happens, the modest initial shot count grew to more than 400 vfx shots. Visual Effects Supervisor Kent Houston and VFX Producer Mary Stuart divided up the sequences between London-based Peerless Camera Co. and Digiscope in California. At Peerless, the project was shepherded by Digital Supervisor John Swinnerton, Digital Producer Marianne Speight, CG Supervisor Ditch Doy, 2D Supervisor John Swinnerton, and Animation Supervisors Tim Ollive and Jamie Tremelling.
The telekinetic fights presented some serious challenges, as characters had to be seen hitting walls, crashing into ceilings and falling down staircases in a most brutal manner. "We worked very closely with Second Unit Director and Stunt Supervisor Nick Powell to do as many of these effects as possible in camera," Houston explains. "We assisted where needed doing wire removal, painting out specially-prepared pieces of set, and enhancing bodily impacts where required. The stunts were very physical and extremely brutal. In some cases, the sets were built to yield slightly to prevent injury to cast or stunt crew. In post, we made everything look much more rigid by either painting out or replacing anything that appeared to give. This made the bodily impacts appear much more jarring. In general, the wire rigs were designed to be well concealed, in or above the set. We did do a lot of additional paintwork covering up the various slots, arms and wires, and favored this technique over construction of CG sections of the set. In the end, we didn't need any CG doubles for those scenes."
Digiscope tackled a majority of the telekinesis shots. Digital Supervisors Dion Hatch and Brent Prevatt oversaw the effort, along with Digital Producer Terron Pratt. "For nearly all of these shots, we simply worked the effect over the stunt action," Hatch says. "There were a few cases where we had to rotoscope the stunt performers and change either their trajectory or speed. We also added CG debris and dust on some of the shots to enhance their impact with the walls or the bamboo scaffolding."
One of the trickiest aspects of the project was locking down the design of the "mover" effect. Some of the psychics have the ability to produce bursts of pure energy, a concept that proved difficult to visualize. "The script originally described the effect as 'air warps'," Houston recalls. "Paul McGuigan was very clear that he didn't want any kind of ripple effect. So, after many different tests, we managed to establish a technique that, although very brief, was extremely complex and custom-conformed for each shot."
The team at Digiscope was deeply involved in developing the final look of the 'mover' and 'push' effects. "We knew he didn't want superheroes; the characters needed to be human and act human," Hatch notes. "We started with our standard arsenal of plug-ins, from GenArts and The Foundry, to get through some initial do's and don'ts. Then, we tried image manipulations, extended bicubics, warp-meshes, and we also tested looks in 3D using volumetric light effects and fluid simulations. We did at least a hundred tests on the 'mover' and 'push' effects, and we just put them all in front of Paul. He picked his favorite bits, ultimately favoring an initial chromatic burst that we combined with slight image warping and time shifting of the backgrounds to simulate the paranormal event. Then, even though we had a formula, it had to be customized for each shot. There was a lot of painting involved, as this procedural effect would often not be focused enough to the target, or its dissipation rate might be to slow, kind of like trying to wrangle particles. In order to correct for this, we had to do quite a bit of paint back to the original. We used either Flame, Inferno or After Effects, creating a shared methodology that would work on all of these platforms."
The same set of tools was used in both facilities: Syntheyes for tracking and matchmove, Maya (plus XSI at Peerless) for modeling, rigging and animation and mental ray for rendering. Peerless employed Shake or Fusion for compositing, while Digiscope worked with Flame, Combustion and After Effects.
The mutants' eyes played a key role in the action, as whenever a specific power was exerted, the character's eyes would change color and shape. "For instance, there is a criminal group called the Popboys who have the ability to smash objects using ultrasonic sound they can emit," Hatch adds. "We had to alter their eyes each time they screamed. First, we warped their irises inward to look reptilian, then we ran a textural displacement across the eye. The effect is high-energy creep, but we have to be watching closely to catch it. For the 'push' eye effect, we knew it would have to emanate from the pushers' eyes. Though pupil dilation is a standard in our industry, we ran all types of tests looking for something unusual, but it seemed that the more complex we made this effect, the more ridiculous the result! Ultimately, we combined paint and warp brush techniques together on the convex meniscus fluid of the eye. It gave an impression that the under structure of the eye was actually changing. Once again, we specifically created a look that could be shared on both Combustion and After Effects."
High Rise Showdown
All those techniques were in high demand for the end sequence, where all protagonists meet and a dramatic series of fights ensue in an atrium at the top of an unfinished skyscraper. To start with, the building never existed -- it had to be created via CGI. "The sequence required that we constructed a 60-story building and dropped it into the middle of downtown Hong Kong. When we started working on the sequence, I was amazed to learn that in China, all the scaffolding, even on the tallest skyscrapers, is made of bamboo, and this in turn, is covered with a green mesh safety netting. Kent supervised the shoot and supplied us with hundreds of textural and environmental references. The lower exterior would have to match the location building, and the top of our building would have to match the look of the stage set, with two-story-high orange and blue windows, as well encompassed in the scaffolding.
"The CG building was used in seven shots, including two aerial flyovers, and had to be dressed for day and night shots. We used a park location in downtown as our anchor point, tracking in a matte painting of a ground construction site, and then compositing in our CG building on top. We spent special attention to the exterior elevator shaft on the side on the building. In particular, we added lights along the metal railing to give a sense of scale for the night shots. The CG building was created in Maya in 64-bit on Linux Fedora Core 5 -- which was a nice learning curve for our IT team. In order to get maximum control in composite, we rendered out the ambient occlusion and alphas separately. We did run into some sampling flicker issues with the fine detail of the netting, which we corrected via 4K renders on a few shots."
For the interior of the building, Digiscope created what became known as the "void," a large central shaft that fell away 60 floors to the ground below. The final confrontation takes place on a partially constructed glass flooring suspended over this void. "We originally planned to do these shots with the shaft being a 2.5D projection, but as Paul began to add and subtract features, we shifted over to a fully-3D construct," Hatch explains. "Kent asked that the lighting be irregular, some floors dark, while others would only be lit by work lights. He also wanted lights running down the sides of the shaft to enhance a sense of vertigo. To make sure that we got the best look of the void, we rotoscoped all the actors, so we could control the density of the glass floor."
In the end, the ultra high scream of Pop Father brings about a tremendous collapse of the bamboo scaffolding. The majority of the effect was achieved in-camera using large-scale practical effects. "We added CG bamboo that fell close to the actor, and amped up the dust in the foreground. Some were rigid body simulations, but we also had a few bamboo sticks that broke apart, for which we used traditional key frame animation."
What started as a small side project ended up being a major endeavor for Houston. "This film was made with a relatively tight budget and a short shooting schedule, so we had to be very efficient on set, and were also required to be very prudent with our vfx budget. I very much enjoyed the experience of shooting in Hong Kong, and I'm also very happy with the look of the film. Director of Photography Peter Sova and Production Designer Francois Seguin created a wonderful environment for us to embellish." Adds Hatch, "Working with Paul and Kent was an enjoyable collaboration, and I think that, in the end, we reached their mandate: create paranormal events that are visually exciting, but never over the top."
Alain Bielik is the founder and editor of renowned effects magazine S.F.X, published in France since 1991. He also contributes to various French publications, both print and online, and occasionally to Cinefex. In 2004, he organized a major special effects exhibition at the Musée International de la Miniature in Lyon, France.