The first thing you notice about General Grievous, the new all-CG villain, is that he isnt very villainous. He coughs, he skulks, he hunches over and hes not particularly menacing. Thats precisely what George Lucas had in mind for this character thats part droid and part alien a precursor, if you will to Anakin/Darth Vader. He thus represents the technology that will ultimately consume Anakin, but in his case the technology is not yet perfected. But then, when he strikes, he takes you by surprise, leaving no doubt why hes such a ferocious force.
Grievous came to us as a blank slate, explains animation director Rob Coleman. The designers worked with George at the Ranch, providing him with a bony mask. But they didnt have time to discuss how he would move. It wasnt until we got in him in the computer and got him to move around that he was helping tell us how he should move.
[Hes comprised of] a mechanical outer shell and a creature on the inside. He has very complicated mechanics with certain restrictions to his body. He doesnt have free range of movement. In the early tests, Grievous would be portrayed as sly, cowardly, staying in the background. Hes a bit like Fagin. In fact, we talked about Fagin as well as classic vampire movies, including [Werner Herzogs] Nosferatu. Since his movement was so restricted, we decided to have him talk with his hands, because, although there is a grill pattern where his mouth would be, there are no articulating bits for his mouth. No lip synch or facial expressions. No brow to move. No indication of what he is feeling or thinking. So we relied more on body. His hands are stacked on top of each other and they move similarly to Nosferatu.
Coleman is proud of the fact that Grievous, like the CG Yoda, is fully animated without the use of MoCap. There is great use of subsurface scattering in his character. Episode III benefits from global illumination improvements with tight close-ups of Grievous and Yoda. Weve also put in subsurface scattering and created new shaders to handle skin because we specifically knew George would want to come in closer [on these CG characters]. We wanted something special about Grievous performance and wanted him to have an animated look. We wanted the control of his physicality.
Digital modeling supervisor Pam Choy, meanwhile, was given few clues at the outset other than Grievous was part mechanical and part organic. You could see his eyes and that his guts remain part of his core but that he has been completely redesigned. In early artwork, he looks a lot more droid-like. I was told that he was going to have unique abilities: he moves his arms up, and that hes very quick and spider-like.
When I came on the show I was given a bucket with the one maquette that was made at the Ranch and a few plastic pieces. This was a very rough concept. They wanted him to be mechanical but sculptural. There was still much to be defined: Whats going on his neck area? How do his arms connect? Whats going on in his pelvis? How do his toes connect?
Choy reveals that Grievous was upright when first designed until more than two-thirds of the way through modeling when Lucas and the design team decided to make him hove a lot until his exciting hand-to-hand battle with Obi-Wan on the sinkhole planet Utapau, when he stands upright and reveals himself for the first time.
Obviously we had a lot of issues to work through. Part of the modeling task is not just to build the model but also to make it mechanically functional. That was a huge challenge. There were art department drawings attempting to deal with these mechanical issues. In the initial design, the neck on the clay sculpt is just a rod, but then they provided a piston with sculptural details. I had to figure out how to make this work from a modeling standpoint. Sometimes artwork fleshes out more but may also bring up more questions. I realized that while the pistons around the neck were a good idea in terms of allowing his head to move, they wanted to see a lot of hoses around his neck, too, which constricted his movement. And how would the shoulder fit?
Then there was chest detail: It was very compact but there were flexing issues when hes bending over since the chest is one whole piece. Then youve got a lot of rigs pressed against each other. Then there were issues with the pelvis. Normally when you walk there are a lot of rotations going on. The initial design had one whole piece holding the pelvis together, so how do you separate them so they arent rubbing on the hip bone and these back pieces arent hitting the back? As for the arms, they became more complicated later on with the addition of smaller pistons. One arm would move and separate, but one arm was initially shorter than the other and for it to break off, they had to be the same length.
Choy adds that there were times during the initial design phase when some of the animators thought that Grievous would make a cool toy with lots of different motions, but many of these suggestions were not workable. One of the things you discover as you begin modeling is that not all of the concepts work in 3D. This is the first time that I encountered instances of the 2D artwork not translating into 3D. One thigh piece had individual movements with each of the pieces shaking as he walked. But realistically it became very difficult to accommodate when you connected all of them. You have several knee pieces, several cap pieces and you want to try to avoid hitting things on the hip. So we talked to Rob Coleman and he said it would be easier if we have it move as one single piece like a regular side, to treat it as a single bone rather than a myriad of pieces.
When it was decided to have Grievous hunch over, there was a major proportional change along with it. Initially, he was a lot wider and possessed more girth. But then he went from being seven feet tall to eight feet when upright. Grievous was also a lot leaner. They also took his torso and compressed everything in and altered his legs. They pulled the chest plate down more along with his neck base piece, which was also pulled forward.
At the last moment, there were major changes to Grievous eyes and mask when it was determined that he wasnt mean-looking enough. After the model had been approved and the paint was close to done, I was asked to increase the distance of the ridge, Choy continues. The mask took his eyes too far down in close-up. We changed the shape of the eye to make it angrier. It was a significant change that clearly works in the film.
Moreover, the mask was elongated, the eyes became more detailed and mucous was added later on to heighten the dramatic effect. Metal pieces off the mouth were also added. As far as the troublesome neck area, pistons and tubes were applied but they relied on simulations so they wouldnt have various parts collide. The chest area became compact with pieces fitting on top of each other. We broke it up so that it looked more spine-like, Choy suggests. We also added sunbursts in the back that connect to the ribs and holds things together connected to the pelvis. We broke up the pelvis differently so pieces could all move separately and didnt penetrate each other. The thighs were built as multiple pieces functioning as one thigh unit.
The surprising payoff to Grievous, of course, comes during Obi-Wans long pursuit and climactic fight on Utapau, the big wow moment when it is revealed that Grievous is no longer a sniveling villain but actually a worthy adversary. Grievous turns out to be a Jedi-trained expert at lightsaber dueling, who takes pride in sporting the weapons of his prey inside his cloak.
After studying a lot of the concept art, I asked George what is the best way to dramatically sell the fact that Grievous is a strong and imposing character, explains sequence supervisor Glenn McIntosh. In other words, how this guy with four arms actually going to fight, so I studied Rob Roy, Phantom Menace, Gladiator, Ray Harryhausen movies. And I kept coming back to Kali in The Golden Voyage of Sinbad because its the only thing that comes close with Kali having six arms and Grievous four.
So I did a bunch of sketches and spread them out on a table in front of George after animation dailies and asked what he liked. And he immediately responded to two sets of arms and so a lot of sketches made their way right into the fight sequence and it evolved from there, including the idea of the lower and upper arms switching to take advantage of the fact that hes a cyborg.
So I had done these tests of his arms spinning and I made sure that the animation worked three-dimensionally. I took a camera and filmed from different angles and offered George a lot of options. This allowed George to wrap his hands around this sequence and go from there.
According to animation supervisor Jamy Wheless, they not only studied Nosferatu but also Bruce Lee films in preparation of the fight sequence. But it was Lucas idea to up the ante for the demise of Grievous. George instructed us to have the gut sack pulsate during the fight once its exposed, Wheless adds. The idea was to have Obi Wan discover the gut sack as his most vulnerable and organic region.
Moreover, Lucas wanted to see Grievous eyes reveal surprise when Obi-Wan attacks his guts and have his body explode like a roman candle when Obi-Wan finishes him off. Its that extra little touch that tops it all off and gives it a dramatic finish.
Bill Desowitz is editor of VFXWorld.