Re-creating the sinking of an 18th century trading ship
By Karen Moltenbrey
In 1773 the Royal Captain, a British East India Company trading ship carrying a treasure trove of precious tea, silk, and porcelain, struck an uncharted shoal and sank in the South China Sea while journeying home from its yearlong maiden voyage. More than two centuries later, French businessman-turned-underwater-archeologist Franck Goddio finally located the sunken vessel, after spending years and a small fortune doing so. He was not disappointed-the wreck was a great historical find.
Anxious to share the Royal Captain's story-both past and present-with the world, Goddio teamed up with ThinkFilm (Washington, DC) and the Discovery Channel to shoot live footage of the excavation/recovery process. But to tell the whole story of the Royal Captain required a step back into history-to the Royal Captain's tragic voyage during the height of England's shipping trade. This was done with 3D computer-generated imagery to re-create the ship's past, providing a historical counterpart to the present-day efforts, both of which were presented in a recent Discovery Channel special titled Treasures of the Royal Captain.
Unlike most 21st century treasure hunters, driven by the hopes of finding a sunken chest brimming with gold doubloons, Goddio, an underwater archaeologist, was seeking clues to a way of life that no longer exists. In his quest, Goddio conducted extensive research on the period and the ship itself; he even uncovered a document containing excerpts from the ship's logbook, recounting the crew's efforts to save the ship and the eventual sinking. Although the Royal Captain was a merchant vessel, it was nonetheless a magnificent state-of-the-art ship of its era. Thus, to archaeologists like Goddio, it was priceless in terms of its ability to transport historians back to a time when England raised its status on the seas from a nation of pirates to one that controlled more than half the world's trade.
|To help recount the ill-fated journey of an 18th century shipping vessel for a television special, artists created a 3D model of the boat, which was used in the sinking shots (right), while a highly detailed physical scale model was used in most of the ab|
Remaining true to Goddio's commitment to preserving history required a painstaking effort on the part of the 3D modelers at Interface Media Group (Washington, DC), who were charged with re-creating and sinking an authentic digital replica of the 18th century vessel. "Our job was to use animation and digital effects to tell the story of the Royal Captain and illustrate its demise," says Carol Hilliard, the 3D artist who completed the assignment. However, boats of this type contained an intricate cobweb of rigging attached to the sails, which would have been almost impossible to accurately depict in a CG model. So director Joe Becker of ThinkFilm commissioned an accurate physical model, built to 1/75th scale, that was used for many of the above-water shots, while its CG twin was used in the sinking shots. "The physical model was extremely expensive and delicate, so [Becker] didn't want it to touch the water," Hilliard notes.
To ensure that the CG ship matched the scale model, both Hilliard and her more traditional counterpart used the original blueprints from the Royal Captain as a guideline. As she received updates from the English model maker, Hilliard would then tweak her Alias|Wavefront (Toronto) Maya model. "We were sort of making parallel progress," she says.
|To ensure that the digital and physical ship models matched as closely as possible, both modelers used blueprints of the actual vessel as a guideline.|
The most important issue, though, was ensuring that the CG textures precisely matched those of the wooden model. To do this, Hilliard used Adobe Systems' (San Jose, CA) Photoshop for pulling off the colors and textures from digital photos of the scale model. She also used Maya Paint Effects to create the scratches on the lower part of the digital model, illustrating how the boat listed for days prior to sinking, scraping on the shoal on which it was caught.
Once both models were ready to set sail, the team at Interface Media Group shot live footage of the physical model against a green screen, tracking the camera movement with Maya Live for insertion into computer-generated water and skies. Pulling all those green-screen keys for cutting around the rigging for compositing the CG backgrounds required a tremendous amount of work, recalls Jeff Weingarten, senior compositor. Using the camera data, Hilliard then created wakes and other environments in Maya, and the other water effects, including the vast ocean, using Arete Entertainment's (Sherman Oaks, CA) Digital NatureTools, a Maya plug-in.
The modeling and animation were done using an Intergraph TDZ workstation, while the group used an SGI Onyx 2 for some initial rendering. As "crunch time" neared, the group farmed out the majority of the rendering to WamNet, a digital content management service provider in Eagan, Minnesota.
According to Hilliard, the artists also encountered difficulty trying to generate realistic water. "It frequently ended up looking like Jell-O, and the flow and interaction with the boat was unnatural," she says. "We worked closely with Arete's programmers [who tweaked the code] to resolve these issues and make it work. We had so many camera angles and shots we wanted to achieve, many of them underwater, so we hung in there."
|In all, the 50-minute television program contains about 10 minutes of CG, which had to blend seamlessly with the physical model and live-action elements.|
To achieve realistic interaction between the boat and the water, the group used a digital section of the hull to generate a matte for isolating the waterline. This gave the animators control over the areas that should generate particles, so the water would break around the boat and interact with it. Then the artists added wakes, bubbles, and splashes, generated in Maya's particle system, as well as shoals and reefs. "We added lots of particles, and placed reflections of the boat on the water along with shadows-which helped to marry the water and the model together," says Weingarten. All the elements were composited into the final scene using Discreet's (Montreal) Inferno and Fire.
Originally, the digital ship model was intended for the shots below the water's surface-in particular, the detailed sinking and tearing apart of the boat as it slid down a steep underwater canyon, where the archaeologists eventually located the actual remains. "Obviously we couldn't create that scenario with a live-action model," Weingarten notes. "We intended to use the live-action model for all the above-water shots. But as we got into the production, we found that the 3D model actually performed better in a few instances, especially in terms of matching the water motion to the boat. In those cases, we opted for the 3D version."
According to Weingarten, the biggest challenge was the seamless integration of the live-action green-screen model with the Maya model, but he and Hilliard agree that for the most part, viewers will be unable to distinguish between the two. "Creating realistic interaction between both models as well as between the models and the computer-generated water, sky, and shoal elements proved tricky," he says. "But it was the little details such as the bow wakes, fog, twinkling stars, and such that ultimately brought the shots to life."
Besides the boat and backgrounds, the digital artists also replicated the boat's actual blueprints in Maya, creating a wireframe-like image that sprang to life to portray the construction of the original vessel at the beginning of the program. "That showed how the boat was built and gave the various dimensions of the masts and even the number of cannons and how they were placed," says Hilliard. It also played a vital role in the re-enactment; the water that eventually flowed through the cannon portals during the ship's listing is what led to the sinking.
According to Hilliard, when the Interface Media Group artists signed onboard with ThinkFilm, Becker was up front with his plans: He wanted to give this project a far more realistic quality than what had been accomplished for previous documentaries, which typically have limited budgets. "I think we achieved that," she says. "The images don't compare to those in Titanic. When you look at the [Royal Captain's] sinking sequences, you can still tell that it's CG, but it's a far cry from what has been done on similar low-budget documentaries.
"It was a fun project," concludes Hilliard. "And I learned more about ships than I will probably ever need to know."
Maya, Alias|Wavefront (www.aw.sgi.com)
Digital NatureTools, Arete Entertainment (www.areteis.com)
Images courtesy Interface Media Group.