CGSociety :: Production Focus
16 December 2011, by Renee Dunlop
Director Paul W.S. Anderson’s swashbuckling stereo version of The Three Musketeers battled its way across film screens everywhere this fall. But it was the competent artists at Mr. X in Toronto who added the dazzle and dash to scenes that touched on everything from animated toy soldiers to battalions of floating ships. CGSociety spoke with Digital FX Supervisor Eric Robinson and Lighting Supervisor/Look Dev Lead Trey Harrell to learn more about what it took to bring the film to life.
TOY SOLDIERS
The opening of the film is a battlefield of animated toy soldiers. Director Paul Anderson wanted a map shot that told the story of Europe in the 17th century. “He wanted to go from a flat map to having depth and contour” as the stereo camera flew over the map, explained Robinson. “We came up with the idea of making them look like painted miniatures, sourcing historically accurate models to tell the story of armies encroaching on France as the beleaguered France tries to defend itself.” Burning villages were added by the FX department, the modeling team produced close to 50 unique models for soldiers, infantry, artillery, and cavalry from different countries. To achieve the stereo requirements from a camera view so close to the map, Robertson, who previously worked in stereo conversion at IMAX, used a shallow depth of field to help sell the feel of miniature photography.
Elements were rendered out of Maya using V-Ray,Houdini and Mantra. “In the past we’d had shots where it was either one system or another but the technical needs required us to go for a more hybrid approach.” The map had to be extremely large and detailed. The camera starts a few feet off the table then flies down onto the map and hovers. “That was a challenge because to make the map detailed enough it was a tremendous memory hog at 96K resolution. Around the Pyrenees we had to do a secondary pass to make the mountains look more detailed. As the camera goes past Paris it shows the gold king and queen so getting their reflections, the gleam took a combination of lighting and comp tricks.”
STEREO
Robinson’s stereo background helped solve challenges such as implying the size of the ships against the backdrop of the sky. “If you are standing on the ground looking at a blimp, it’s very far away and you don’t really appreciate the stereo. It doesn’t feel dimensional when you are looking at it, so you have to find the balance between realism and interesting.” As the air ships battle over Paris, they crash on to the Notre Dame Cathedral. “We had to make these things look big enough to do some damage, to hold a full crew of men”. To do this they used a stereo RED camera setup fixed at six inches interocular, “the difference between the left and right lenses. We used that as a starting point and dialed from there. So to make the stereo work would be a combination of interocular and your convergence point, the point at which these two lenses are aimed.” By changing the convergence the subject would appear closer or further away from the viewer, and changing the interocular makes the dimensionality feel stronger or weaker. A narrow interocular makes things feel flat, while a wide interocular makes them feel round and dimensional.
But the risk of going with too large an interocular makes things look miniature. A balance must be struck to achieve the correct feel of scale and where the object sits in space. The shots were being worked on as the air ships were being built, “so we’d have animation proxy models so we could start the process but the models themselves were extremely complicated with tons of detail, so it took a long time for teams of artists to build them. So to get the show done on time we had to do things as in parallel as possible.”
The CRASH AT NOTRE DAME
Notre Dame was built to minute detail and the initial push was for the first trailer release. It was no easy task according to Lighting Supervisor/Look Dev Lead Trey Harrell. “Our model and textures weren’t actually finished for the roof until maybe 24 hours before our trailer deadline. During previs the camera wasn’t moving much so Paris started as a bunch of stills. “We assumed 90% of the background in Paris was going to be matte paintings. As we got closer to our deadline we realized we had to do a combo of full 3D ate paintings as well as a ton of hero rendered Paris. We’ve got somewhere around eight square miles of medieval Paris built surrounding Notre Dame.
From a comp perspective, especially with keying and roto work, stereo shows are more than twice the amount of work, especially for doing roto on something like hair. “With the short production time that are common in the industry today, that goes to the shoot as well. So a lot of times we can’t pull keys of somebody’s hair, and we had a lot of hair to key on this show.” There was a lot of lace too. “It’s an absolutely massive amount of work to do roto and keying in a stereo environment. Anything that is even a pixel off shimmers or looks the wrong shade.”
IT'S IN THE DETAILS
A big challenge for the show was how much had to be gong on the screen all the time and how detailed everything needed to be. “In the past,” said Harrell “you would build a medium resolution model and only render high res details on a per-shot basis. Knowing Paul as we did, we knew that as close as the camera had gotten during previs we would probably be twice as close, with the camera flying around by the time the final shot came out. So we couldn’t make any assumptions on how well the models had to hold up.” The airships were close to 50 million polygons for the final show. “To give you an idea, the balloons alone were 64 separate 4K texture tiles, the hulls of the ship were close to 80 4K texture tiles.” The Three Musketeers was the first show where Mr. X adopted Mari in the texture painting pipeline. “The challenge was how were we going to paint at this level of detail, with this many textures where a lot of times we had to get in microscopically close to the hull of the ship or the balloons. In the hull of the ship, in several shots we get down to the point where you can tell that somebody stripped a bolt.” Many pipeline tools were written in order to support the “absolutely ridiculous amount of data we were working with.”
The airships were built by the assets department led by Chris MacLean. They are built with a combination of Maya, ZBrush, and Mari with a bit of Photoshop. “The textures took a library of basic surfacing prototypes that our Look Dev leads put together. It allowed our texturing or modeling artists to take look development to around 90% to the finish line. In the past with Mantra or PRman based renderers it would take a dedicated shader writer or TD to write custom shaders and lights and calibrate every model. With the V-Ray system we had global unified calibrated texture and lighting environment so the texture artists could take a basic wood (etc.) that would be calibrated and present well.”
