Just released in the UK, Tooth Fairy presented a number of vfx challenges, including a classic that has been a corner stone of visual effects for decades, – as part of a tooth raid Dwayne Johnson character needed to be shrunk down and invade a child’s room while being no bigger than a match book. We spoke to VFX Jake Morrison as to how they solved it.
Jake Morrison and the team at CIS Vancouver solved many problems for Director Michael Lembeck’s kids film Tooth Fairy, from particle systems to flying rig removal.
The film solved many problems old school, for example nearly all the fairy wings in the film are practical elements.
One of the most interesting sequences involves Shrinking Paste for a tooth fairy raid on a child’s bedroom. The challenge is one that has been addressed by many great visual effects artists over the years, in movies such as Gulliver’s Travels, Honey I Shrunk the Kids, The Borrowers, The Indian in the Cupboard, Tom Thumb, Night at the Museum, Land of the Giants and many, many others.
The problem is one not just easily solved by computer graphics, rather it is best served by a combination of old and new school techniques.
For Jake Morrison, he started the process of solving this particular scene by referencing many of the films that have tackled this problem before, and cutting together a reel of shots and elements that both worked and some that didn’t. From this he compiled a set of rules or guides for creating this type of shot.
Scale: The most obvious point is the need to establish a scale and build to that. In this case, it was decided that a 12:1 scale was ideal.
Camera: Morrison decided that ideally Dwayne Johnson should be shot from above wherever possible, “You need to shoot from just above them if possible, as that always helps with the sense of scale,” he explained. Matching the camera angles very acurately between setups and plate photography is important. The key to selling the shots was a reduced depth of field Morrison determined early on, giving the viewer the sense of macro photography. Additional depth of field was added to many shots in post.
Weight and scale: As foreground elements were often oversized, getting the materials, textures and scale right was vital. If cloth was to be scaled, the master Dwayne Johnson props would need very large weave, stiffness and weight. Any wood grain needed to be giant, any stitching needed to be vast, and of course fabric patterns needed to be made to the correct scale.
Interaction: “Most important for me was the interaction,” pointed out Morrison. As Dwayne Johnson was surrounded by real props – the actual blend line or key line was nowhere near where the audiences eyes would hopefully be looking in the shot. It also had the added benefit that the actors weight coud cause the ‘bed’ under him to depress, and the pillow he climbs under to completely react to his movement. “Props and art department design did a great job, making sure the big props looked right – hair on the toys clumped correctly etc. as much as was possible… but there is only so far you can take that…and if it was not looking completely believable, then the guys at CIS Vancouver would track in cloth, weave and detail and deform it as his feet pressed down on it,” he explained. This digital matte painting style overlay added a much higher level of realism.
Lighting: Not only is it key to keep the light direction and intensity correct, but the quality of light changes. “At that scale even a single light blub becomes an area light,” thus all of the lighting matches for Dwayne Johnson needed to be softened and broadened, as “you expect softer shadows.” The film is a comedy, so while the entire sequence is meant to be lit only by moonlight, the director was quite specific that the stars of the film needed to be seen. “We cheated a bit – did things like make the wand glow – but definitely the director wanted the audience to see everything.” Mainly the team was concerned with scaling the height of the lights to get them high enough in the studio space they had – and similarly not film both sides of the plates so that they did not need to have to dig trenches to get the camera low enough on a matching background.
Greenscreen: It was decided to minimize the use of greenscreen as this often lead to very unrealisitic composites. The costume of the Fairies was satin so greenscreen would always be difficult due to reflections and spill. When comps were done, they were ideally designed so that a significant part of the foreground would be included as part of the composite, which in turn added key weight to the art department requirements.
There was some greenscreen work of course. The film was shot on Kodak 5219 which “makes for good latitude for greenscreens, but I find it quite a ringy, noisy stock, esp. for darker bluescreens…the latitude is much kinder to the DOP, but we do need to start scanning EXRs to get the full range, otherwise we’re clipping the neg for VFX,” commented Morrison.
Frame rate: A trained cat also made the team’s life complex, since it needed to be over cranked to at least 48 fps to add scale and weight thus helping to sell the scale of the cat from Dwayne Johnson’s characters’ point of view, which also ran into limits of available light. “As you know as you increase the frame rate, you lose your light and you lose your focus.” Morrison would ideally have shot as high as 120 fps but light limits would not allow the crew to go above 48fps – while maintaining any chance of the focus puller managing to hold focus as the camera was moving back on a dolly in front of a running cat. “The only problem with very shallow depth of field – even if it would be right – is that it starts to look like rear projection…which is why we put in a few pull focuses to break the planes up. It is the same problem with people jumping from planes, when you are traveling with the jumper – it is just hard to make that shot look right – that is one point where if Dwayne’s character had had some trailing pixie dust or something to break the multiplane – it would have helped, but the sequence is so.
Shadows: To get the correct shadows and avoid just having composited fake shadows, a special floor was made so that if the special studio floor could not be used in the shot then at least a special shadow could be rotoscoped and matched rather than just faking a shadow. As the wood grain needed to match in two different directions this 48 x 40ft floor was built on rollers so it could be rotated to give the correct wood grain for which ever way the action was playing out on screen. “We shoot out one angle – then everyone – the grips, the crew, everyone – would push this floor around so we could shoot back again into the greenscreen in the studio. It was fun if nothing else,” he joked.
For Morrison, one of the great aspects of this production was how keen the lead actor Dwayne Johnson was to get the effects right, “He’s done this before, he gets it. He was always wanting to check his eye line and know what it was going to look like, ” Morrison explains. “Oh and one other thing – he has amazing muscle memory! There is a sequence when his fairy costume comes on for the first time…that was done with maybe ten passes of motion control – layer upon layer upon layer of costume – and while we did nail his shoes to the ground(!) – he is still moving in the shot. He looks down and tilts his head back and it was just spooky watching that back on playback- every single pass was spot on – his acting identical to the previous take – his muscle memory was amazing,” recalled Morrison.
Frantic Films, Entropic, Evil Eye Pictures, and Hydraulx (LA) also contributed to the visual effects of this film.
Tooth Fairy is in UK Cinemas now and on DVD in the USA and elsewhere.