Issue: Volume: 25 Issue: 7 (July 2002)

Space-age Construction

IMAX uses a digital sequence to set the stage for its live-action space film

By Karen Moltenbrey

From Kazakhstan to the Kennedy Space Center to 220 miles above the Earth, the live-action 3D IMAX film Space Station takes moviegoers on the journey of a lifetime as they witness firsthand one of the greatest engineering accomplishments of our time-the in-orbit construction of the International Space Station (ISS). The ster eoscopic production, which was filmed in space by astronauts and cosmonauts using IMAX 3D cameras, chronicles the true-life efforts of modern-day explorers as they build and inhabit the permanent research facility in the deadly vacuum of space.

Through a photorealistic 3D sequence, viewers are also introduced to the perils and rigors that these space-age architects must prepare for during their training inside a simulator at Hous ton's Johnson Space Center. The two-minute digital sequence, created by DKP Effects in Toronto, provides a dramatic opening to the large-format documentary film, which was produced by IMAX Space Ltd. in conjunction with NASA. The animation depicts an astronaut maneuvering precariously outside the ISS, when suddenly his tether snaps, and he begins to drift out of reach. He then activates his jet pack "life jacket" to return safely to the ISS.

"We were charged with providing a realistic window into the training that precedes a person's launch into space," says Chad Nixon, creative director at DKP. In fact, the segment is based on an actual scenario from the real-time virtual reality training simulator. NASA provided the animators with a video of the VR experience, which the team then used as a guideline for the dramatic sequence. The objective was to make the audience believe that the digital segment was actually part of the documentary filmed on location by the astronauts-until the CG shot dissolves into a live-action sequence of two astronauts inside the simulator.
Animators created a dramatic photorealistic scene for a live-action documentary about the International Space Station. To build the authentic-looking model, the artists used high-resolution photos of the station taken from space, schematic drawings, and l

Successfully accomplishing the subterfuge hinged on the authenticity of the computer-generated imagery-a task that became even more daunting because of the large-format presentation, in which the slightest glitch would stand out on the 80- by 60-foot screen. "Our animation had to be believable-from the Earth's surface to the specific fibers of the [astronaut's] spacesuit," says Nixon. This was achieved, in part, by using photographs and other reference material from NASA, which provided a guideline for creating the digital models of the ISS, astronauts, and a variety of objects inside Side Effects Software's Houdini 5.

For replicating the Extra Vehicle Ac tivity (EVA) spacesuit, the group digitally scanned the garment and patches worn by astronauts during a specific space mission. Using Paraform surfacing software, the group then generated a smooth polygonal mesh from the point cloud data acquired during the scanning process. Next, the modelers imported the surface data into Houdini, where they set up the character's skeleton and bone structures, then animated the 600,000-polygon model using forward and inverse kinematics, taking into consideration the movement re stric tions in space, as referenced from the film footage.

The team also generated a realistic texture for the spacesuit in Adobe Systems' Photoshop using pieces of scanned cloth and other materials from DKP's library, such as those used for creating creases, wrin kles, and other snippets of realism. With Houdini's VEX scriptable shading feature, the group also created displacement maps that helped give the EVA suits their signature fabric weave and the gloves a rubberized look.

"Creating the displacement on the texture surfaces added to the high-resolution detail since it physically alters the geometry," says DKP animator Craig Barr. "There's only so much you can fake with texture maps and shaders, especially at the resolution we needed." The group de termined early on that it couldn't use standard bump maps for any of the textures because of the stereo effects. Other wise, it would have looked as if there were a flat object sliding across the object surfaces whenever the perspective shifted, he notes.
The proportions of all the CGI, including the objects in this scene, were accurate. And, since there is no atmospheric distortion in space, the far edge of the Space Station had to be as crisp as the closer areas.

To create the ISS and space shuttle En deavor models, the group again used a variety of reference materials from NASA. "Every thing on [our model] was exact, down to the location of the handles on the ISS modules, the grooves in the surfaces, and the individual bolts that hold the surfaces together," Barr describes.

The animators also created surface scenes of Earth- from the Great Lakes to the Yucatan Peninsula-which were developed by stitching together high-resolution NASA satellite imagery to create a 1.5gb texture map. Despite this process, sometimes the model of the Earth did not look realistic enough. To rectify those shots, the group softened the imagery by adding a blue atmospheric haze, which made it look authentic.

After the models were built and textured, they were rendered with Houdini's Mantra 5, which uses the VEX language, running on a renderfarm of Linux-based machines. "We were able to achieve the quality we needed right down to the reflective, raytraced surfaces of the as tro naut's gold-mirrored visors," adds DKP producer Linda Gillies. In all, more than 6000 frames were rendered at 4k resolution during a 35-day period, leaving little margin for error. The various layers of imagery were then composited with Nothing Real's Shake.

The team added an extra level of realism to the digital sequence by adhering to scientifically correct details, and using accurate distance, dimension, position, size as so ciations, and inter-relationships among the objects, as provided by NASA. For in stance, the artists calculated the exact rotation of the Earth as it would occur in real time, and animated the model ac cordingly.

"The director was not only concerned with the drama and the story line," Nixon says, "but also the perception of the public as well as those at NASA, including the as tronauts who had experienced the scenery firsthand."

Key Tool: Houdini, Side Effects Software ( infoNOW 96