Treat no.2 for VFXer's- An insight on Sorcerer's Apprentice

For The Sorcerer's Apprentice, visual effects supervisor John Nelson oversaw more than 1200 shots featuring plasma ball fights, a Chinese dragon, car chases, magical creatures and the re-creation of the famous Disney Fantasia sequence. We take a look at some of the key work by the two lead facilities, Asylum and Double Negative.

The film tells the story of sorcerer Balthazar Blake (Nicolas Cage) who recruits unlikely physics student Dave Stutler (Jay Baruchel) as his apprentice. Together they help defend New York against the evil Maxim Horvath (Alfred Molina) who is trying to release other sorcerers from the Grimhold, a magical prison similar to a nesting doll. To conjure up the visual effects for the film, director John Turtletaub looked to John Nelson to consider that both magic and science can sometimes be indistinguishable. "One of the things we wanted to develop is that magic is physics and physics is magic," said Nelson. "Physics is basically magic that has been quantified and explained specifically, but there's many things in magic that are waiting to be discovered." Nelson split the work between Asylum, Double Negative, Method Studios, Rising Sun Pictures, Company 3 and an in-house team.

This effect in which hundreds of thousands of streaming cockroaches are forming into a human mass, Asylum handled the cockroach transformation as a large behaviour simulation. Other effects included an animated dragon ring, a remote sword fight between Barthazar and Horvath and particle simulation shots of the two being sucked into an urn

 Asylum augmented the wolves to make them more vicious. A traditional Chinese parade version on the street was turned into a living, breathing monster, a transition created by Asylum.

A car chase sequence through New York featuring morphing vehicles and a magical Hungarian mirror was also handled by Asylum. After a small accident on the first night of location shooting, production could only drive the cars up to 25 miles per hour. Along with constant rain, this meant Asylum had to add more CG shots and create speed ramps for the chase.

For a scene in which Dave plays music to Becky via large Tesla coils in his lab, Double Negative created the necessary lightning effects. They designed a system where they could choose particular frames where the bolts connected and that would be the hero frame.

Using the actual bronze bull as reference, Double Negative obtained a 3D scan and built a model using Zbrush, Mudbox and Maya. Initially they tried to match it with the original satue but ultimately they made a few changes to make it a bit more intimidating, like sharpening the horns. There was a balance to be struck between having realistic muscles and skin sliding, and trying to give it a more rigid feel to reflect the metallic nature of the bull. The lighting was primarily image based. They had great access on set to acquire HDRI light probe images and the bronze material of the bull leant itself to this kind of lighting. They were also re-projecting the scans onto rough geometry of the location and ray-tracing against that to get realistic ground reflections.