Suspension of disbelief is the currency of any action movie in which actors perform feats of physical prowess. Audiences wouldn''t expect comedians Will Ferrell and Jon Heder to actually attempt the icy escapades in Paramount/
Dreamworks'' Blades of Glory, but directors Josh Gordon and Will Speck didn''t want to cheat the action by simply showing the backs of stunt skaters'' heads. As Ferrell and Heder leap their way through hilarious ice-skating routines, the camera is close and very personal. The ability to capture every comedic grimace comes courtesy of the face replacement techniques achieved at Rainmaker Animation & Visual Effects in Vancouver, Canada.
“Face replacements aren''t new, but people are used to seeing them shot with lock-off cameras,” says Visual Effects Supervisor Mark Breakspear. “We''ve seen face replacements where actors are running at camera and not turning their heads. But with ice-skating, the relationship to the camera changes dramatically all the time. We did about 150 face replacements in this film and every single relationship to camera was different. You''re spinning, going up and down, and bending over. Will Ferrell is an actor who could use those moments to make us laugh, so we couldn''t just put a CG face on a skater. It had to act like Will Ferrell.”
Rainmaker began with a plaster cast of the actor''s face, which was then made into a mold. That mold was scanned at high resolution by XYZ RGB in Ottowa, Canada, so that pores and small wrinkles were visible. “We knew we were going in close enough that audiences would see those details,” says Breakspear. After applying textures culled from photos of the actor''s face, Rainmaker arrived at a CG likeness. But making the face ‘behave'' like Will Ferrell was the real challenge, and Rainmaker developed a PCap system to do it.
They placed about 150 tracking dots on the actor''s face, but not in a conventional grid-like pattern. Grid arrangements can miss the subtleties of an actor''s distinctive facial style, observes Breakspear. “We studied footage to see what part of his face moved when he did a ‘Will Ferrell performance.'' We concentrated the dots within those performance areas.”
“Then we put the actor in a ‘hall of mirrors'' that showed his head from every angle. Straight in front was a 35mm film camera that recorded the facial performance. Placed around this were three HD video cameras that captured all the dots from each mirror. It was like doing a 3D Suduko puzzle,” Breakspear says.
For each shot, the actor would view clips of the stuntman''s performance to get a sense of the physical timing of a skating move. Then, with the four PCap cameras rolling, the actor would put his own spin on the facial performance he would have given if he''d been skating. The result was a library of facial takes.
Once the selected takes were locked in, explains Breakspear, “We scanned that footage. We had a time code generator that linked the HD shots to the film. If, for example, we had 120 frames of film representing a shot, then we had three 120-frame sections from the HD cameras at left, center, and right. That made one package of data.” That data was run through RealViz MatchMover Pro to compose a 3D object. The point cloud of data that resulted from the MatchMover analysis contained each moving dot on the actor''s face in 3D space.
Rainmaker''s system then took this data and applied it to the CG face models. “We wrote software that worked out which parts of the face moved more than others,” Breakspear says. “You''d think it would be straightforward, but skin below the cheek moves more than skin next to the nose. If a face is upside down, gravity pulls it a certain way. We had to figure out directional controls.”
“There was a lot of processing. The model was 15-million polys, so we couldn''t load that into [Alias] Maya. We used in-between software called CySlice, [from Cyberware], which allowed us to open up the model and make tweaks to it,” Breakspear says. “If we''d only had one face replacement to do, this technique would be overkill, but this movie rested on face replacement.”
For the other end of the pipeline, Rainmaker tracked the plate shots of the stunt doubles doing jumps and spins—so it would be clear where the CG heads were supposed to go. The studio used proprietary software to track the way the stunt double''s face moved. Breakspear''s team also had to track the background environment because the stadium where the skating was filmed would later be replaced with a CG stadium. To track the backgrounds, Boujou [from 2d3] was used.
The crowds and the stands needed extensive CG work as well. Breakspear had filmed about 1,000 extras watching the skaters perform in a 15,000-seat stadium, but some scenes were supposed to be taking place in 45,000-seat venues, so new geometry was needed. DP Stefen Czapsky lit the actual stadium—even though he knew it was going to be replaced—as he would light it for real. “We always had references for what the lighting should be,” Breakspear says. “Stefen understood our process, even though software packages don''t talk in the language of a DP, which is crazy. Somebody should write tools that equate to real lights.”
Rainmaker also MoCapped the real extras to create digital doubles, and then populated the arenas with CG people using Massive Software. The 3D-CG elements typically were generated in Autodesk Maya and rendered in Mental Images Mental Ray.
Significant rotoscoping was also required to remove all the wires and rigs that the stunt skaters used, and Autodesk Inferno was Rainmaker''s tool of choice. “When you have wires going through actors'' hair and going in front of extras, that causes all sorts of problems,” Breakspear says.
To complete this 380-shot assignment, Breakspear says, “We had a team of about 150 people. We had a lot of fun doing this, though working on a comedy is definitely not as funny as watching one!”
Directors: Josh Gordon, Will Speck
DP: Stefen Czapsky
Visual Effects Supervisor: Mark Breakspear
Visual Effects Producer: Randy Starr
Executive Producer: Shauna Bryan
Visual Effects Producer: Ashley Clark
CG Supervisor: Kody Sabourin
2D Supervisor: Mathew Krentz
Lead Inferno Compositor: Martyn Culpitt