3-D digital effects supervisor Mark Lassoff, co-supervisor Judith Crow and a team of 30 were responsible for creating the unique human figures populating the Titanic's decks. As Cameron planned epic shots sweeping down the glorious length of the ocean liner, Lassoff and Legato selected countless DD employees to go down with the ship. "People who moved well and showed that they could be directed ended up being on board," Legato says. "And you could really pick them out in the finished scenes: the [digital figures] moved like the people we chose. Motion capture shouldn't terrify actors, because it won't replace them. We discovered that we really needed actors to create the performances and do things that were dramatic. Even though we were doing something impossible with the camera, it was still no different than having those people actually perform the various actions."
Still, Titanic's decks had to teem with thousands of these CG extras. The solution: cloning. "We built a library of people, composed of various portions and movements, which we mixed and matched and altered to make endless walk cycles," Legato relates. "At a distance, there are certain details you can't make out, so we used a lot of the same people wearing different-colored costumes, and appearing in sunlight or in shadow just to create the impression that these were real moving people. Fortunately, we didn't have to create computer-generated costumes; we could just generate shells, apply a texture map of real fabric or real costumes that had been photographed conventionally, and then light each figure individually.
"Pretty soon, we found ourselves creating the sense of actual people, and some of the shots we did were alarmingly real. They didn't look computer-generated, because they were patterned on real people and real performances. Certain motions were not 100 percent there in absolute close-up, but our approach really paid off once we shrunk our motion-capture people to the proper sizes and stuck them on the ship. At that point, they started to develop some soul, and to look like real people. If you'll pardon the expression, we've only exposed the tip of the iceberg with this technology. As we get better with the technology, a scene like this will become more and more convincing, until it's just another shot in the movie."
Hewing to the concept of shooting the Titanic for real, Cameron began filming a number of sequences on full-scale replicas of the ship's midsection (extending from the captain's quarters to the end of the promenade deck) and poop deck. Both of these structures were built in a huge water tank on Rosarita Beach in Baja, just south of the Mexican border. As shooting progressed, Cameron wanted to see more and more of the Titanic; the poop deck was soon connected to the rest of the ship, which had been extended to the tip of the bow. When all was said and done, Cameron had built virtually 90 percent of the Titanic. "All that was missing was a 40' section from the absolute tip of the bow to the well deck, where the mast was," Legato recalls. "That was taken out for technical reasons the tank was only so big. It was a huge logistical nightmare to work with a giant ship in a giant tank filled with water; the only way the crew could drive the big cranes carrying the cameras and lights through was to make a hole in the boat."
Back at DD, 3-D digital effects supervisor Judith Crow (T2 3-D) was building on the work she and Legato had begun on Apollo 13, spearheading the development of a Prisms software pipeline that would allow the effects team to plan each shot and keep track of various elements as they passed from artist to artist. "Prisms is the program of choice for quickly setting up a scene and determining what all of the issues are going to be," Crow says. "We organized all of the data in Prisms first, then jobbed the work out to DD artists, using every software package we could get our hands on. We R&D'd many things we hadn't done before on Apollo, but there was nothing that felt impossible. There was a scarier edge to the work we did on Titanic, though. We had to develop a few things on this show which, once we started, we didn't know if we could make work."
Crow's 3-D digital artists did a great deal of R&D on new processes for tracking camera moves and reconciling motion-control data. These techniques would help to extend the Titanic set and add CG ocean plates to Cameron's inevitably fluid shots. One such development was a system that used stereo photographs of sets to reconstruct physical environments in the computer. Crow's team used that data to extract camera moves and apply that motion to the CG ship extensions and/or ocean plates. "It's like digital surveying," Crow explains. "By photographing the set with twin cameras mounted a known distance apart from a known angle, we can use software to derive the location of points in three-dimensional space from the features in the photographs. Once we've reconstructed the geometry of the set, we can extract camera moves from it.
"That works for smaller scale, closer shots. For wider shots, we would place a teepee-shaped object in the set, and then take photographs using a handheld camera from two different angles. We could later reconstruct the set from that known geometry. We used these methods for all of the effects shots filmed in Mexico. Any time we had to do a digital extension involving a set with a part missing, we would reconstruct the data to derive the camera moves and the geometry of the set, and then use that information to track our CG ship extensions and water and sky elements onto the full-scale Titanic."
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