A fractured fairytale: Hansel and Gretel

Actors on broomsticks, an animatronic giant troll, plus ‘fun’ blood and gore – these were just some of the effects challenges for Norwegian director Tommy Wirkola with his first big-budget film, Hansel and Gretel: Witch Hunters. Visual effects supervisor John Farhat tells us how the work – finished in stereo – was done.

The black comedy take on the classic Brothers Grimm story turns the tale on its head with Hansel (Jeremy Renner) and Gretel (Gemma Arterton) becoming witch bounty hunters. Production took place in Germany at the Babelsberg Studio, and on location in a forest near Berlin and in Braunschweig. Principal photography was shot on the ARRI Alexa (with this being one of the first shows to capture in the ARRIRAW format) using Stereotec rigs. Most of the visual effects plates were acquired with Red One and EPIC cams. Stereo D handled post-conversion.

Watch the trailer for Hansel & Gretel: Witch Hunters.

How to make witches fly

On the trail of evil witch Muriel (Famke Janssen), who has been orchestrating the abduction of several children, Hansel and Gretel encounter several broomstick-riding foes. Scenes of the flying witches were generally filmed with actors against greenscreen and then combined with cable-cam footage shot in the forest. In one scene, the siblings set up a bunch of wires between two trees as a trap for one of the witches, leading to her being sliced up as she passes through.

To film the background plate, Farhat oversaw the cablecam shoot of a RED camera flying along a quarter mile of forest. The greenscreen shoot then incorporated rolling broomstick rigs and a Technocrane used to glide past them. “We couldn’t necessarily fly them around on broomsticks,” notes Farhat, “so we would sometimes be flying the environment around them, rather than flying them in an environment.”

See how the cablecam rig was used in the forest.

Hammerhead, the main visual effects house on Hansel and Gretel, then combined the plates, painting out cable rigs, cleaning up the ground and adding CG wires and a blowing trail of leaves and debris behind the broomstick. At that point the witch is seen coming straight to camera, with body parts, including her head, flying in different directions – for comedic effect the witch’s head retains a horrific look as it enters the audience’s 3D space.

An earlier shot of Muriel attacking a village with a fireball featured a CG city and greenscreen plates of Janssen on her broom. “We did an animatic of what we wanted the witch to do first,” explains Farhat. “So we had a previs witch and then on stage we used an Encodacam system where they rigged every axis on the Technocrane, encoded the axes, and we could comp that in realtime against the previs.”

Watch a short clip from the greenscreen shoot showing a broomstick scene.

“We took the camera information and generated a motion path of the camera out of the previs and then we were able to build the camera’s track and motion on stage to make it move like the motion path in the previs,” adds Farhat. “Then once you put it together, it went together well, and we just had to tweak it in comp. For the explosion shot we had a crane with an EPIC on the backlot for the house that was destroyed. We literally blew up the house with a giant fireball and we could pull out that explosion and place it into the CG city.”

Enhancing Edward

An eight foot tall troll, Edward, is at first a slave to Muriel but soon helps Hansel and Gretel defeat the witches. Spectral Motion, under creature and makeup effects artist Mike Elizalde, crafted Edward with incredible skin detail and servo operation to be able to deliver an on-set performance and interact with the actors. Spectral was also behind the various prosthetic witch makeups.

For shots requiring the troll to share an intimate moment with Gretel, and for other scenes, Hammerhead augmented the animatronics in CG. Hammerhead also created an entirely digital Edward – based on photo reference and early scans that had to be ‘dirtied’ up – for a scene of the troll crashing through trees to rescue Gretel. “So we added subtle expressions to give him a soul and then also built the CG version of Edward as well as the trees he comes through,” says Farhat. “It made a big difference to being able to have him act face to face with Gretel and then be a violent character when he’s stomping around and ripping people apart.”

Filming Spectral Motion’s Edward on-set.

Extra effects

Hammerhead ultimately produced around 400 effects for Witch Hunters, which also included matte paintings, witch morph transitions, CG gore and explosions, some growing vines, bullets and arrows and wand effects – many of which play out in the film’s finale. Framestore delivered some late-in-the-schedule CG architecture for the candy house Hansel and Gretel visit early in the film as children. And Luma Pictures worked on the post-credits sequence in which a newly formed team of witch hunters deliver some killer blows in a desert setting – here Luma worked on the ‘double exposure’ shot of a witch flipping over to dodge Gretel’s projectiles. “It’s definitely a fun blood and gore film,” says Farhat. “Heads blow up and witches get killed but it’s all very tongue in cheek.”

In this series of shots, Gretel attacks one of the witches. VFX by Hammerhead.