Griff The Invisible - INVINCIBLY INVISIBLE

City Lights
The camera move and transition appear effortless, but VFX Supervisor Phil Stuart-Jones at FSM explained that it turned out to be quite a complex shot to create. “To get the dissolving quote to reform into the city lights, we exploded the matte painting of the city buildings and then reversed that explosion, transitioning from the particles of the quote into the city particles. Meanwhile the camera continues to move back through the window frame, into the flat past Griff who stands looking out, and pans through the rooms in one long continuous shot as the credits start.” The compositing and most other effects work was achieved in Flame, and the particles and other elements created in After Effects. 

The overall brief to FSM from Director Leon Ford was fairly open. His principle concern was differentiating between the looks of Griff’s two attempts at invisibility. Because his first experiment involved impregnating a white boiler suit with a homemade invisible ink made of lemon juice and baking soda, its invisibility effect needed a softer, organic look, but when Griff progresses to his electro-magnetic ‘black hole’ technology using wires, the effect needed electrical impact with an impression of something being sucked into a black hole.

Plate Distortions
Starting with the organic look, the challenge was to make someone invisible but still detectable to the audience. The night sequences, shot when Griff sneaks into his employer’s darkened office, were the most difficult. “We had to shoot Griff twice – once in his white boiler suit, as he was dressed in the story, and then in a green suit we made, allowing us to use green screen techniques to create a hole in the clean plate. We could use the wrinkles in the green suit’s fabric to apply distortions to the plate image that created the effect of an invisible Griff moving through the scene,” said Phil.

“Due to the small budget of this project, we relied heavily on previs. We started working with Leon and the production on the best approach to visual effects for ‘Griff’ a full year ahead of the shoot. All shots and techniques were carefully worked out and tested in advance of the shoot, including camera tests prompted by concern that the night shots in the office wouldn’t provide enough light for the green suit to look green in the image. The two live action passes comprised a very low light pass with Griff wearing his white suit - plus goggles, shoes and small props that were to remain visible so that we had low light references for these - and a fully lit pass to illuminate Griff performing the same moves in his green suit. We also shot the clean plates.”

Time Warp
To make sure the camera moves for the clean plate shots of the darkened office set would work with the performance, some of these were locked off and appropriate camera motion was added in post. Phil handled the invisible Griff’s interactions with office furniture himself by hiding behind a photocopier, for example, and puppeteering the lid up and down.

“Time warps helped ensure that these actions matched Griff’s green screen performance. The temporal plug-in Kronos from FURNACE was used to re-time any actions, such as the difference between Ryan opening the photocopier in two stages and me lifting it in one step while puppeteering from the floor. We used Flames' Stabiliser and FURNACE F-Align to align the multiple plates,” explained Phil. “Although our budget was tight, we did have time to plan these details and managed to complete the shoot efficiently. We also knew in advance that we had to allow time to pull the green screen to create the invisible look within that space, and to rotoscope the goggles and other elements.”

Electro-Magnetic
Later in the story, after his invisible-ink suit gets him into trouble, he tries again with the electro-magnetic suit he devises, inspired by the theory of black holes. The onscreen invisibility was achieved in much the same way. They shot Griff in his new suit, making note of his foot marks from the point at which he opens the office door. Then he repeated this same action, dressed in a green suit, leaving the FSM team to transition between Griff in his ‘black hole’ suit and Griff in the green screen suit in exactly the same position, again using this green screen performance to create a blank space to contain the invisibility effect.

Thus, the composite again consisted of a clean plate shot as the door was puppeteered open, then Griff in the green screen suit, and finally Griff in his invisibility suit. In this case, the distortions were hand animated in order to control all pieces in the shot to follow his path. It was combined with an electrical zap and a sound effect, and made to look as if everything from around his body were being sucked into a tunnel – or black hole.
“The effect itself helped us hide the transition details but the final shot needed lots of cleanup of stray elements and shadows on the walls and stairs. Both types of invisibility distortions were created through Flame, which was also used for compositing throughout the project.

Top Hat
“We used Maya’s particles, however, for the final transition in an action scene when the imaginary villain Top Hat is about to clobber Griff with his cane before exploding into a shower of particles. Clean plates were shot, plus plates with Griff, but with this sequence’s lighting conditions – very dark with bright flashing lights – no green screen was possible.
“All elements had to be rotoscoped and Kronos was used to slow Top Hat down into his final position behind Griff, as he gradually realizes that the whole incident was imagined. Once it reached a certain point, we took the slow motion portion of the footage into Maya and exploded the character with Maya’s particles. Then we wrapped this effect around Griff and dissipated it as he became fully visible to the viewer.”

This was not only a complex shot but differed substantially from the previs – planned as a shot of a fist punching toward Griff’s point of view. Phil and his team had been on set every other day of the shoot except this one. News of the change came via a frantic phone call, but once the work was done everyone agreed the slow motion and particle dissolve added to the drama and communicated Griff’s transition to reality more effectively. The high action nature of this sequence, employing the flashing light and no locked off shots, required using the F_ Align plug-in as well to realign the three plates in the shot, plus hand animation to compensate for the flashing. Meanwhile, the camera was also zooming in and back out.

Film Grain
The overall look of the film, shot on 16mm, often combines comic book looks and compositions with the lighting and camera angles of a Hitchcock thriller. The film medium caused some problems for the team, whose digitally generated shots contained edges that were too smooth to match the film grain. A substantial level of noise and grain had to be added back in to the edges of matte shapes in the composites to help them sit naturally into the images. They used the Genarts Sapphire plug-in, carefully tweaking the results.

The grain of the 16mm film also made the chroma keying more challenging. Fortunately for the purposes of this film they didn’t need such a clean edge but were mainly after the form and shape, and were able to pick up the high and low lights in the original green screen suit to base the distortion on. Nevertheless, the tests, previs and look development all stood them in good stead.

On Location
Virtually all of the locations and much of the action the audience sees are real. Actor Ryan Kwanten playing Griff performed almost all of his own stunts as he runs through the dark streets of Sydney clad in his shining black superhero’s suit, and only a few wire removals were needed for the fight scenes. The office window shots revealing expansive views of Darling Harbour were also real. The production took over a vacated office overlooking the harbour for these sequences.
Phil said, “We found a suitably small, dingy property in Balmain to use as the set for the flat interior, although the alleyway outside it was shot in the city. The ‘flat’ was actually a ground floor cottage on the grounds of the old Balmain hospital. To save the VFX budget for other shots, we used a large Duratrans to provide the city backdrop in all scenes except the opening shot. The monitor replacements of black hole images for Griff’s home IT lab were created in Smoke and composited.”

Particle Physics
Griff’s girlfriend Melody is as fascinated with particle physics as Griff is with invisibility. Her research convinces her that the particles comprising solid objects should be able to re-arrange themselves to allow a person to pass through them. FSM’s job was to prove her theory correct. In a critical sequence, their visual effects allow her to fall through Griff’s door and into his flat without harming herself or the door. They first shot her leaning back against the door, and then with the door replaced with green screen, falling backwards on wires. But in the end, they found they needed to rotoscope most of the elements needed for the sequence.
“The hardest aspect was working out the plane along which she and the door should intersect as she fell through it. To tackle this, I built a 3D model of her, using geometric block shapes, and then matched her movements so we could determine the correct location of the intersecting plane – both where the door starts to give way, and where she would start to disappear from view as she passed through it. In post, the composite of Melody and the door included hand-animated mattes and distortions to soften the edges of the door around her, and a particle effect.”

Frame Morphing
Phil had wanted to shoot this sequence overcranked for slow motion but as the production was running short on stock, no one was keen. It was shot at 24fps as normal but, of course, Leon came back to them afterwards regretting the decision. So once again they created the slow motion in the final shots using Kronos, which required a lot of retouching. “Kronos is good for morphing between frames, adding the missing frames in between, but distortions inevitably occur, especially where objects intersect. So many of the frames generated needed hand painting. This is why we had to do a lot of rotoscoping – once we had retouched Melody’s falling shots through the door, the green screen wasn’t so relevant.”

The camera position started outside the flat in the hallway in front of the door with Melody leaning back against it and a hole cut into it for her to put her head back into. Then the shot cuts to inside the flat, looking at the door from the interior as her shape starts to form as she falls through, with a slight particle effect. Then the camera returns to the hallway, to shoot her falling back toward the green screen before finally shifting back inside to shoot her complete fall to the floor.

“With hindsight and a bigger budget,” Phil considered, “I would have set up a witness camera to clearly see the required angles, but by the time they were shooting the sequence, time and film stock were running out. The late decision to slow the footage later added another unexpected dimension to the job.”

“Instead, we shot a clean plate to capture the empty cardboard interior of the box, and then shot Griff in front of the box with a fluorescent light inside for the interactive lighting. His hand and actions were rotoscoped from this plate as reaches out to touch the suit. We made a full animated plate of the CG ‘universe’ to use in the composite, and a real suit was also shot to help define the folds and creases to apply to the animation to complete the suit,” said Phil. “Applying the right amount of movement and swirling to this shot took several iterations, and having all the elements in place gave us the flexibility to reveal part of the box interior as he touches the suit.”

Invisible World
Melody is the only person in the story who doesn't see Griff when he is invisible, and dons a special pair of glasses to be able to see him. We share her point of view through the glasses and see Griff standing in a pure white ‘invisible world’. “We shot him against a white screen and also shot a clean plate of his flat where they were standing, and then composited in traces of that image around and through the edges of the white background to suggest that he was occupying a special, physical state,” Phil said.

‘Griff The Invisible’ waited quite some time for its March 2011 release after it was shot during November 2009. FSM’s first meetings with Leon Ford took place in December 2008, when they discussed feasibility, budget and what would best be achieved in-camera and using visual effects. In the end, they completed just over 70 VFX shots. “I was sometimes talking myself out of a particular task purely because we thought that, given his budget and the story, some sequences would look better shot as live action.

Facing Facts
“For example, when Griff finally has to face the fact that he  is not a superhero crime fighter and that his gleaming, high-tech IT lab - capable of everything from criminal surveillance to research into black holes – is just a collection of shabby, outdated computer hardware and cardboard boxes, the audience too suddenly sees the reality of its condition. Griff lashes out and sweeps it all aside in a dramatic and emotional shot panning around his little flat. We urged Leon to capture it all in camera, telling him we couldn’t heighten the drama further with VFX. I think the result in the film proves we were right.”

Phil said, “The team’s detailed previs, testing and onset supervision were major factors in keeping to Leon’s budget. With that planning stage behind us, the DP Simon Chapman and crew were able to do all of our green screen shoots for us and understood why scenes had to be shot twice, lit two different ways. We had the two set-ups ready to go and could do the takes back to back, which helped make them as similar as possible. We had all seen the tests and knew the results we were looking for.”www.fsm.com.au

Words: Adriene Hurst
Images: Courtesy of Transmission Films

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