Atypical Stereo
Issue: Volume: 26 Issue: 7 (July 2003)

Atypical Stereo

By Karen Moltenbrey

In 1995, film director James Cameron went the extra mile—to the bottom of the Atlantic Ocean—to research the wreck site of the Titanic for his 1997 blockbuster film of the same name. Yet, the more he probed, the more questions he had about the tragedy. So in 2001, hoping to find some answers, the director again traveled to the ship's underwater tomb. Using new camera and film technologies, he captured images of the Titanic that were previously unattainable during his first visit and incorporated the results into the stereoscopic IMAX film Ghosts of the Abyss, which takes viewers wearing polarized glasses deep inside the maze of the ship's interior to show what life was like aboard the ill-fated luxury liner.

Thanks to newly developed camera technology, Ghosts of the Abyss takes IMAX viewers to new depths with large-format stereoscopic imagery and digital effects. All images copyright Buena Vista Pictures Distribution and Walden Media, LLC.

With Titanic, Cameron was at the forefront of technological innovation and artistic vision, overseeing every detail of the Oscar-winning movie. Costing $200 million, the feature was one of the most expensive ever made, employing groundbreaking computer graphics to make the synthetic seem real. The new film employs some of the same types of effects—such as superimposing the passengers' "ghosts" (played by actors) over images of the actual wreck (see "Deep Effects," pg. 45). But the real breakthrough in Ghosts of the Abyss is the result of new HD and stereo camera development, which enables the audience to experience the journey as if they were part of the dive team.

"People have seen Titanic before," Cameron acknowledges. This time, however, the experience is intensified by the visceral nature of the 3D technology and made more personal by the fact that the focus is on the wreck and its history, and not the dramatic retelling of the event using traditional Hollywood storytelling techniques. "I wanted to give audiences the same experience that was such a life-changing one for me—to plunge down through 2.5 miles of water, to experience something as strange and exotic as the wreck of the Titanic, and to really feel it and see it," says Cameron.

Filming the high-definition, large-format, deep-ocean documentary required 40 tons of equipment, most of which was designed or modified specifically for this project. Mike Cameron, James's brother, spent three years developing the submersible technology that allowed the group to traverse the interior of the Titanic and explore the ship in a way that had never been done before. His company's two Remote Operated Vehicles (ROV) were equipped with high-tech cameras, their own light sources, and more than 2000 feet of fiber-optic cable, which connected these so-called bots to two submersibles (Mir 1 and 2), from which the ROVs were launched. Mike Cameron's Dark Matter LLC company designed each ROV with a self-contained, high-density battery onboard, which eliminated the need for a large tether and afforded unprecedented freedom of movement. It also meant the ROVs had to be as light as possible to maximize the power source. Built from lightweight foam and weighing only 80 pounds each, the ROVs were small enough to slip into previously inaccessible areas of the ship and maneuver through the narrow passageways to film in rooms not visited since the ship sank nearly a century ago.

"We went into every space on the Titanic that was big enough to permit the ROVs to enter," says Cameron. "We went into staterooms, where we saw people's beds, sinks, mirrors; we knew who was in each room, and we found their clothing and personal effects. We went into the hold and looked at the cargo. We went into the dining room and saw the beautiful leaded glass windows that are still there, intact. The elegance of the Titanic still exists, but it has remained beyond the reach of all previous expeditions, including ours in 1995."

Filming in this harsh environment on the ocean floor also required new camera technology. The typical camera used to capture IMAX imagery weighs 240 pounds, requires special supports and rigging, and can only shoot a few minutes of film at a time, making it impractical for this project. Moreover, the system had to fit into a pressure housing for the underwater trip. So Cameron, working with Sony and Panavision, developed a lightweight digital 3D camera that could overcome those issues, as well as deliver the final product in practically any release format—and actually film in stereo. The 22-pound Reality Camera System includes two customized Sony HD-950 24p cameras set the same distance apart as a set of human eyes (roughly 70mm)—the first large-format-capable camera system to do so.

This 3D HD camera system, used to film approximately 80 percent of Ghosts, was then mounted on the outside of the Mir mini-subs carrying the crew, including Cameron and Titanic star Bill Paxton, and was used inside the Mirs and aboard the expedition's mother ship, as well. Conversely, because of their small size, the ROVs were outfitted with much smaller standard-definition cameras. The sub interiors were fitted with small "witness" cameras that recorded the events inside the sub onto DVCAM.

Prior to filming, Mike Cameron made sure the new camera system would function safely and reliably at the required depth. He also devised a sophisticated pan/tilt mechanism that enabled James Cameron to operate the camera as if it were mounted on a tripod directly in front of him, rather than on the outside of a sub.

This bed frame, filmed by an ROV, gives a rare, personalized look inside a stateroom. This standard-definition imagery was later combined with 3D HD footage.

Following the underwater expedition, Ed W. Marsh, creative producer at Cameron's EarthShip Productions, began processing the 900 hours of raw film footage shot during the expedition. After this was done, one of the main challenges was finding a way to "fit" the standard-definition footage shot inside the Titanic by the ROVs into Ghosts' stereo format. "Because the film was going to be shown in IMAX format, the screen would be too large to just fill the frame with standard-def material," says producer Janace Tashjian.

The group's solution was to create "windows," occupying anywhere from 10 to 50 percent of the overall screen, which would contain the ROV material. To provide a sense of depth, says Marsh, a team at Modern VideoFilm in Burbank, California, placed the flat images in the stereo space by building a left- and right-eye version of the film footage, and synchronizing the two. "We then created the feeling of stereo by crossing or splitting the images," says Roger Berger, lead editor at Modern VideoFilm. The effect would then appear near or far depending on the setting of the "spread" between the two versions.

Further complicating the process was the fact that the footage was shot in various formats—not only standard and high definition, but 24P and 60i. Using Quantel's new iQ editing system, the group translated all the material into the same HD format. According to Berger, the iQ employs a resolution co-existence feature, which enabled the editors to work with and output from multiple video clips of any resolution and format without any pre-conversion of the imagery. Thus, by working at full resolution, there was no degradation in the quality of the imagery.

With the iQ, Berger and his group later assembled and composited the film to conform to the original film edit completed by Marsh, Sven Pape, and John Refoua. Yet, even the naturally filmed stereo segments sometimes had to be split and reconverged "because there was just too much material for the eyes to handle," says Berger.

Working with a da Vinci 2K Plus color-enhancement system, Scott Klein later color-corrected and timed the film. Last, the group used Modern VideoFilm's in-house theater setting to ensure that the stereoscopic effects aligned properly. The high-tech room is equipped with a large screen and two Digital Light Processors from Texas Instruments, as well as a 35mm projector.

Reproduced by permission of English Heritage. NMR.

Top is a photo of the first-class dining salon. Bottom is an image taken from the ROV that shows much of the ship, including the ornate windows, is still intact.

In addition to appearing in IMAX theaters, Ghosts of the Abyss will play at 3D-capable theaters throughout the country.

Karen Moltenbrey is a senior technical editor of Computer Graphics World.

To augment the film footage, other postproduction facilities besides Modern VideoFilm generated digital effects for Ghosts of the Abyss, including Creative Logik Universe (CLU) in Glendale, California. Working closely with historians, CLU created a range of 3D imagery, including CG representations of the Titanic's infamous Marconi (telegraph) room and the first-class dining saloon. Intended to be explanatory, these particular images did not have to be photorealistic, but they did have to be historically accurate and rendered in stereo to match the film's final format.

For another sequence, the CLU artists digitized archival pictures of the Titanic, and processed the high-resolution images into stereoscopic images. "Our job was to make left- and right-eye versions of the photos so they could be presented as if this were an old-time stereogram," says John Bavaresco, who along with Al Lopez founded the facility. "And, we were under strict orders [from Cameron's studio] not to alter the integrity of the photographs in any way."

The photos—which mostly showed the ship's construction—were scanned at very high definition. The resulting images—which averaged 550mb in size—were difficult to work with, so the artists scaled back the data to a manageable level and found that none of the detail in the pictures was lost. Using NewTek's LightWave 7.5 and Discreet's 3ds max, the group replicated the objects within the photos, then front-projected their 3D images onto the pictures, giving them depth. "We had to work in real-world scale for the 3D convergence to work correctly," says Bavaresco, "requiring us to establish a unit of measure by analyzing the objects within the photo."

Perhaps more challenging, though, were the "mosaic" shots, or the underwater scenes of various rooms constructed from the non-stereographic film footage acquired by the ROVs. Working with Cameron, Bavaresco and his group forged a solution.

First, Cameron provided dozens of clips from the ROV footage, which CLU then used to generate the 3D environment. In short, the group created a huge panorama from the video footage, placed it on a large 3D model of the scene (in some instances generated by Cameron's own CG unit), and then illuminated it, as it would appear underwater. Yet, creating an image map that was large enough to hold up at high def was challenging, especially since the map had to be generated only from the video footage provided by Cameron. "We couldn't paint or embellish the images in any way," says Bavaresco. "The situation was similar to the one we faced with the archival pictures, only with these scenes, we had to incorporate underwater lighting and atmospherics."

CLU re-created the ship's telegraph room (top), and Stephen Pavelski of Cameron's Section L group replicated the grand staircase (bottom).

To accomplish this, the group worked with the panorama of the scene, layering and tiling multiple images together in Adobe Systems' Photoshop and taking care to balance the lighting between the image tiles, since all the footage was illuminated from a light mounted onto each ROV. Once the artists had a clean, detailed panorama, they then had to make it three-dimensional. First, they analyzed the image for a sense of scale, like they did for the archival photos. Then, they determined which elements in the image had to be modeled in 3D.

"One of the trickiest parts was figuring out what's behind what, and where these objects sit in 3D space," states Bavaresco. To make this determination, the team reviewed the original video footage and found shots where the camera traveled horizontally over a number of frames. They then created a left- and right-eye stereogram from these adjacent frames, and wearing polarized glasses, determined the location of the images. "We were charting new territory," Bavaresco says of the process.

CLU rendered all the imagery in high definition and handed it over to E-Film in Hollywood, which added live-action greenscreen elements. The segment was then integrated into the film at Modern VideoFilm. The imagery was finally "up-rezzed" and recorded out to IMAX film format by CFI Digital. —Karen Moltenbrey

CLU artists re-created this CG image of the dining area, using original footage shot by the ROVs as a reference.

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