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HOLLOW MAN: Memoirs of an Invisible Motion Control Operator
A behind-the-scenes look at filming the visual effects.
By Les Paul Robley
August 10, 2000
words that strike fear and loathing in even the most seasoned film crews. The process traditionally takes longer than normal camera setups, and has suffers from a higher degree of Murphy's Law, despite the superior accuracy one gets from controlled movement. Nevertheless, it was a necessity for Columbia Pictures' new science fiction film, Hollow Man
, for director Paul Verhoeven (RoboCop, Total Recall
) decided that the only way to bring his invisible man to life was to have star Kevin Bacon on set for all the sceneseven when he couldn't be seen. This required that multiple takes of each shot be filmed, with and without the actor, and the only way to get perfect repeatability from take to take was with motion control.
One of the main requirements for motion control demanded by visual effects producer Scott Anderson, director of photography Jost Vacano, and director Verhoeven was that it not reveal itself as motion control. The equipment needed to be easy to set up and versatile enough to be effortlessly re-rigged as shots were modified on set. Most importantly, nearly every shot involving invisibility required a motion-controlled camerabut the film needed to look on-screen as if it had been shot with a free-moving camera!
'There was so much motion control on the first and second units of Hollow Man
that I made a point early on to try and have the equipment accepted by all departments as standard production gear,' recalled mo-co operator Eric Pascarelli. 'I have often encountered an 'Us vs. Them' mentality toward motion control on live-action sets, and I wanted to avoid it on such a long project. The equipment was designed logically and performed so well that by the end of the show, no one even thought of it as motion control. It was just another camera rig.'
To accomplish this, Sony Pictures Imageworks' silent, servo-driven 'Stealth Dolly' was used for the entire nine-month shoot, along with several special rigs made by General Lift of El Segundo, California. (The latter company also supplied motion control for Verhoeven's previous space epic, Starship Troopers
.) For scenes involving Kevin Bacon's invisibility, motion control was required because each take of him would be immediately followed by a 'clean-plate' pass to provide the background that had been obscured by the actor. Extra passes of the same shot might be used for other elements, such as smoke and fire, or splashes, bubbles and drips in the wet scenes. The track, boom, pan, tilt and focus axes were played back together for each of these clean passes without anyone in the plate, so that all camera movement would repeat precisely for the later digital compositing stage.
Bob Sterry and Bryce Shields of CompMagic worked as visual effects video assist operators on Hollow Man
. Chris Cundey's Redondo Beach company provided on-set video composites for some of the more complicated sequences, in order to make sure that the motion control repeated accurately. 'We triggered the mo-co with timecode, then played back the live-action passes with a simple video dissolve against the clean passes to make sure the moves lined-up precisely,' said Sterry.
The difficult shooting requirements for Hollow Man
may be considered special if for no other reason than this marked the first time a fully-immersed underwater motion-control camera rig was used in a feature film. 'This was actually the second time for General Lift,' explained owner Joe Lewis. 'The shots we did for Starship Troopers
became our first experience in dealing with moving a camera around under water and repeating the same move. We fabricated an underwater housing that contained the lens only, which had limited range of motion in how deep we could go. VCE of Sylmar, California, composited all the passes where Johnny Rico's [Casper Van Dien's] massive leg wound [prosthetic replacement] was made to appear as if it was being repaired by the biodoc in the stasis tank.'
For Hollow Man
, more ambitious shots were proposed requiring a greater range of motion. Because the camera was completely immersed, depth was not the usual restriction. The entire pan/tilt head, and all cabling, had to be waterproofed so that it could be submersed as far as necessary. The rig also had to facilitate shots beginning underwater and breaking the surface. It needed to be very fast and powerful so it could handle the sudden changes in buoyancy.
'Hollow Man's use of wet motion control, or 'Hydrodynamic Motion Control' as I called it, was required for two different sequences,' explained Lewis. 'One was a swimming pool at a suburban Washington DC home (on stage 12 at Sony Studios in Culver City); the other involved the secret subterranean lab corridors beneath the city (stage 15). I met with Sony Imageworks' visual effects supervisor Scott Anderson and visual effects producer Susan MacLeod, along with overall production visual effects producer Kenneth Silverstein, early in the spring of 1999 to discuss requirements for the show. We came up with a set of specifications based on the storyboards, which we used as a guide. Later, as the production entered December of 1999, Phil Tippett and Craig Hayes of Tippett Studios in Berkeley, CA were brought in to take over these sequences.'
The action in the pool involved the violent drowning of the character played by William Devane by the invisible Kevin Bacon. The system needed to be versatile enough to travel with the action as it moved from above to below the water's surface. As with the dry motion control, all axes were controlled with encoders by the same crew of operators. Chris Paxson and Dan Besocke of General Lift acted as mo-co technicians for the pool shoot and supervised the primary machining and fabrication. Pascarelli handled all of the data record and system playback functions using the same Kuper software.
'The underwater motion control shoot took place almost a year into the schedule and had to work the same way as everything that preceded it,' Pascarelli pointed out. 'We had achieved a certain pace and method of working that needed to be maintained. Joe Lewis responded to this with a very fast, powerful and versatile underwater rig. The panning and tilting were surprisingly nimble. Not even Paul Verhoeven's whip pans became a problem.'
Kevin Bacon performed practically all of the green-screen passes himself. He was not replaced by a stand-in or double, as is normally the case for an actor inside a green suit. The only shot where a stunt double became necessary occurred when the invisible man is engulfed in flames. For this dangerous scene, two motion-controlled cameras were employed in order to get different angles and not have to reshoot the action twice. One was operated by Pascarelli, the other by yours truly, Les Paul Robley.
The lab Rain Corridor shots employed a high-flow sprinkler system that sprayed about 4-5 gallons of water per second, revealing the invisible man's form by virtue of the water running off his body. As the sprinklers were running, the set floors would flood enabling Kevin Bacon's feet to be seen splashing in the water. As with the pool sequence, the motion control system was controlled entirely by the crew via encoders. What special problems did Lewis and crew encounter while shooting underwater? 'If water can leak or seep in somewhere...it will,' he confided. 'Areas that I thought were going to be potential problemssuch as water dragwere not. Once the system's performance was determined, we established an envelope to work within and, I admit, it worked better than I ever expected.'
The crew's overall consensus toward the underwater mo-co was positive. 'With all that could go wrong mixing electricity and water (and cameras), nothing did,' Pascarelli concluded. 'The humidity was intense and the space was limited on our pool set at Sony. Joe Lewis and all of the others involved should take it as a compliment that while we were working on the wet sequences, no one seemed to notice we were shooting motion control!'Les Paul Robley has been involved in the special effects industry for many years. Occasionally, he writes articles about the technology used in his work.