Sanctum which caves

And then our trapped companions would do the same from below. You make it sound so easy… If you had about another two hours, I could tell you an embellished version would be terrifying. What did you learn about survival from that experience? The inspiration for the movie came from how the people responded after the collapse, how they worked together to survive.

It was like in the Chilean mine disaster. If the community of people there started to break apart, irrespective of drilling holes in the earth and plucking them out to safety, they would have never survived.

And the same way, the people in the Nullarbor basically worked together to get through the issues of the group. And some of the people who you think would be the leaders at the forefront hunker down and become very quiet and accepting of their fate. How did you pull that off? My background is actually in agricultural science.

I worked in that capacity for nearly ten years. The cave diving was really just a hobby. The filmmaking actually started with the expedition when the cave collapsed.

And that will pay for it? So that was my first film. And had it not been for the cave collapse, it would have been pretty ordinary.

So near-death launched your film career? Not this story: So we went to the cave, everyone got on really well, we dove until the end, and nothing happened. But for us, the cave collapsed! So the film that resulted from that was like, wow, really exciting. But I also realized that I knew nothing about making films, so I better learn as much as I can. When did the 3-D interest enter the picture?

That was when I met Jim, which was ten years ago now. Really he had just started embarking on this crusade to learn how to build cameras to film the world in 3-D. So I jumped on board and have been doing it ever since. Now an action adventure movie? We humans see the world in color through two eyes, in stereo. We are trying to create a reality on the screen. Set designers used photographs from real caves to create a CAD model of the set, then built a scale model, in clay, of what they intended to build at the Warner Bros.

Finally, it was time to construct the actual set pieces and put them together in the facility's huge tank. There was flowing water, boulders, rocks.

If you fell over, you were going to hurt yourself. If you didn't know you were inside a studio, you would really think you were in a cave. The pieces were later recycled into a putt-putt golf course. Filmmakers used four stereoscopic cameras: Studio shots were captured with two split-beam rigs created for Avatar, while two side-by-side rigs were used for helicopter shots and underwater photography in the caves of Australia's Mount Gambier. Multiple cameras, however, were used to get various angles of stunts.

Getting the 3D cameras into real caves was tough. That was pretty challenging, but we've done it all before. In the low-budget 3-D cave-diving adventure "Sanctum," a little bit of rain causes a lot of death — by accident, murder and a bizarre amount of assisted suicide. Eschewing such heartwarming tales, "Sanctum," directed by Australian Alister Grierson and produced by 3-D guru James Cameron, is more interested in the savage realities of survival.

Frank's less ambitious year-old son, Josh Rhys Wakefield , along with the team's financier daredevil Carl Ioan Gruffudd and his equally gung-ho girlfriend, Victoria Alice Parkinson , have just arrived. Set deep in the jungle, the mouth of the expansive cave system actually shot in Australia is enormous and cylindrical. You half expect the Millennium Falcon of "Star Wars" to come shooting out with a giant worm in close pursuit. In the complex labyrinth of cavernous chambers and underground rivers beneath the surface, the danger is less alien.

Maneuvering by scuba through underwater crevices as tight as those of " Hours," Frank's mantra is that "panic is the enemy.

It sometimes involved blowing up shots to compensate for loss of imagery after the shots have been shifted within the frame, left and right, to change the angle, but David managed to avoid this as much as possible by rebuilding the missing information from the available footage from both cameras, using Shake for the compositing.

Further shot correction tasks David carried out included removing 'floaters', objects that, only when viewed in 3D, would sit uncomfortably in stereo space between the actor and viewer, causing a distraction. Another issue was the huge amount of rushing water on set during the flooding scenes. If one lens was splashed with water, David could in most cases reconstruct the damaged image from the 'good' eye, rebuilding the frame with a blend of the two in relation to Z depth.

Ben Joss remarked on this problem as well and said a drop of water appearing on one lens is quite hard to cope with in stereo and very obvious on the monitor. Very occasionally, he would need to create a 2D shot to insert into the rest of the footage. Also the headlamps the actors were wearing tended to dominate shots in which the convergence had been changed, and David would have to reduce the detail in the lamps and adjust the shot.

Furthermore, while they read reasonably well in the live action footage, they weren't so successful against green screen and had to be removed and replaced with CG beams, ensuring they were shining in the correct direction to work stereoscopically as well. The effects team's VFX Supervisor Peter Webb explained that a sound understanding of how the brain perceives 3D and processes left and right images helped them decide how to best approach their shots.

Moreover, because a viewer's experience looking at a 2D image in a cinema is slightly different to observing the 3D world, understanding the theory behind achieving a good stereoscopic image was important. The original footage had to be prepared before it went into their VFX pipeline, checking for alignment and colour disparity problems.

The success of all of their effects work would depend on correct stereo alignment and positioning of the convergence point relative to the interocular distance.

The right and left images of shots requiring set extensions and compositing in CG elements, in particular, had to be tracked before the team started work. Their pipeline consisted of Nuke for compositing, Syntheyes for most of the stereo tracking. Aerial Views The editor or director especially liked certain views from the helicopter footage David had shot, but decided some takes didn't run long enough or show the precise angle they wanted to see.

In such cases CG extensions often helped — extending the forest in certain directions and tracking in the imagery.