Shooting The 3D Waterworld Of “Sanctum”

Cannes Film Festival

Universal Pictures

When Alister Grierson agreed to direct "Sanctum," he inherited a bundle of overwhelming challenges.  In addition to the difficulty created by shooting a 3D epic in low-light conditions underwater with a tight budget and safety concerns restricting location shooting, a particular producer named James Cameron was overseeing the entire project.  

"Jim wasn’t going to put his name on the picture unless we delivered a film that met a minimum level of technical and aesthetic production value," said Grierson.  "We had a sense of that throughout the shoot, but I wouldn’t want to make a movie like that anyway."

Andrew White, who wrote the "Sanctum" script based on his own two day cave entrapment experience, had been working with James Cameron on the project with the goal to shoot it in America.  The project was put to the side when Cameron began working on "Avatar."  White then saw Grierson’s directorial debut, "Kokoda."  Inspired by the production values of the low budget war epic, Grierson shot in the Australian jungle, he passed the film on to Cameron who was immediately impressed.  


"When I read the script for ‘Sanctum,’ I had no idea that James Cameron or 3D was involved, it was just a great story," said Grierson.  "Jim saw ‘Kokoda,’ brought me out to Wellington and I spent about a week with him on the set of ‘Avatar.’ I really wanted to bring my cinematographer over, because I thought it might be his only opportunity to actually see this 3D system working.  Jim said ‘Yep, bring him over,’ so I flew Jules over and we spent about a week with Jim just watching him work."



Grierson outfitted his crew with production professionals he previously worked with on "Kokoda."  In addition to cinematographer Jules O’Loughlin, twenty year production vet Nicholas McCallum returned as production designer.  Grierson contacted recent Australian transplant and Oscar nominated editor Matt Warner (Driving Miss Daisy, Lara Croft: Tomb Raider) to cut the film, and veteran sound designer Paul Pirola (Kung Fu Panda, Knight and Day) jumped on board to handle the film’s challenging audio components.



"It’s hard to do water movies, because the temptation is to use the sound of water.  Then you’re left with this mono-chromatic audio landscape, this white noise," said Grierson.  "The way Paul takes you through the water in the scenes is amazing.  There are 20-30 different ways he’s built the water noises.  It’s amazing work."



Balancing organization with spontaneity was key to Grierson and his crew as they began pre-production. Using the storyboard as a guide for action sequences, Grierson found building a 3D replica of the scenes proved more effective in both planning out the shots and finding ways to build sets that trimmed the budget.  Working closely with McCallum, Grierson mapped out tunnel construction that included extensions and angles, allowing the sets to double as multiple locations.  Accuracy in the shooting of the tunnels was crucial, for once the sets were removed there was no means of reconstructing them for pickup shots.



Of the 61 day shoot, roughly 15 days were spent underwater.  To prepare for this, Grierson and the cast and crew went through scuba training and cave diving.  While they couldn’t shoot in actual caves for safety and regulation purposes, Grierson incorporated real locations as much as possible.



"We did things like build a cliff in the jungle to shoot the edge of the doline scene, then we made an extension of that in CG to create the exterior cave environment," said Grierson.  "That gave us huge savings in terms of trying to shoot that on a stage.  For me it was important to capture that on location because it feels real; it feels more like you are in the moment." 



Lighting the cave scenes was a complicated challenge, both logistically and in capturing authenticity.  The caves, in actuality, are completely dark.  Minimal lighting was bounced onto the actors and highlighting the cave surfaces.  The lighting crew developed a system of running portable lights with the actors in the scene, all while having the heavy battery packs and reflectors shielded from the water.



"It was a bizarre dance between the lighting guys.  Shooting some of the labyrinth stuff we had lighting guys that had to be jammed into rocks holding fleck boards while someone else was pointing a light to bounce into the actor’s face, with water spraying everywhere," said Grierson.



The movie was shot with the Pace Fusion 3D camera system.  It allows the converging at either point of focus and makes it easier for a stereographer to alter the final image. But even this phenomenal camera could not overcome the damage that sprays of water might inflict.



"Water and 3D don’t mix, because if you get an aberration on your lens, such as water on your left eye, then you’re buggered," said Greirson. 



To overcome the water sprays that were constantly threatening to obstruct the lenses, key grip Adam Cooper built what the crew called the "air eye system."  A generator operated an air compressor just off set.  The hard, compressed air was sent along pipes up the arm of cranes that affixed to the camera lenses with small hooks.  A sheet of air blew over the camera lens that deflected water off its surface.  Additionally, the camera crew developed specially fitted hoods to cover the cameras and prevent water from going into the camera bodies. Unfortunately, the hoods also held in heat, resulting in over-heating problems.  To compensate for cameras that might over-heat, two cameras were utilized for every shot. 



Most of the shots were done hand-held.  To assist with removing some of the weight of the camera body in the constricting sets, the camera crew rigged a series of cords to the ceiling of the set, acting like a bungie cord, to alleviate the weight of the cameras.  Each camera was realigned daily to correct any camera modifications that might affect the delicate alignment needed to ensure quality 3D.



By shooting the film in Queensland Australia with an Australian crew, as well as performing all post work in Victoria, Australia, a variety of tax credits were utilized that kept the production financially afloat. While the budget was very tight and the 3D required more visual effects than Grierson originally anticipated, he and his crew found ways to save costs while never compromising the quality of the film’s asthetic.  He credits the success of making "Sanctum" to keeping a level head about all aspects of production.



"I tend to be a fairly intense person, a rather serious person, but I’m also a very organized person," said Grierson.  "And I think there’s’ just a level of intensity on set that kind of drives me.  I think if you are as bit flakey, you’re going to be in trouble with twenty set ups a day under a waterfall."