• CGSociety :: Production Focus
    10 December 2009, by Renee Dunlop

    As the New Moon rises, so do the stars at Tippett Studio. Charged with creating the Quileute Wolf Pack for the Twilight sequel, some of the industries leading character artists sunk their teeth into just under 60 shots ranging from three to twelve seconds that were pivotal to the storyline. And those shots are getting noticed. "Strong concept art will save a lot of steps in the CG process;
    it helps to keep the artists from meandering from the final goal." - Aharon Bourland, Technical Art Director,
    Look Development.

    Wolf Mountain and Frankenwolf
    The challenge wasn't just to build a believable wolf, but to build five unique wolves of extraordinary size and weight, to portray that mass often with little more than the surrounding trees as comparisons, create believable fur and humanesque eyes that weren't distracting. Nate Fredenburg, Art Director, helped to make sure those requirements were fulfilled, combining real-world attributes and CG magic.
    "At Tippett Studio, we always look to real-life creatures for reference on how to design our characters, real or mythical. For New Moon, we had a special opportunity to travel down to wolf sanctuary in Southern California to observe wolves up close and personal. The key to looking at live reference is to form a knowledge base, study the creatures, their quirks and behaviors, the language between the pack. We looked for signs of what the creature was about and added those to the visual effects to make them believable."

    In Lucerne Valley, there is a sanctuary called Wolf Mountain where a dedicated group is trying to save wolves from extinction. This is where the Tippett artists traveled to spend personal time with the wolves, many tame enough to be approached and touched by strangers. There the artist could observe behaviors, pack interactions, hierarchy behaviors, and movement, and "closely examine the fur and its different lengths over the body, the coloring variations and markings, as well as the structure of the face, eyes, teeth and so on."

    The trip was extremely fruitful, but Phil Tippett, with his honed eye for perfection, added a second method to study fur under different controlled lighting and wind. "We had a bunch of photographs of wolves that we were studying but Phil was insisting that we take it to the next level and have something to touch, walk around, and actually do your own," explained Fredenburg. This resulted in the creation of what became affectionately known as the "Frankenwolf".
    Tippett bought wolf pelts and cut them up with an Exacta knife and pasted it onto a taxidermy blank "so that we could do a lighting lab in two conditions? controlled lighting on our stage where we could shine very specific lights and look at how the fur responded, then we took it outside on an overcast day, which was perfect for New Moon. We came up with strategies for how to artistically make the wolves look better in flat lighting, which is what we were dealing with and is a very difficult lighting situation."

    Hair Raising
    One of the key observations we made at Wolf Mountain was the complexity of the fur. From nose to tail the fur quality changes, prompting the painters to create a zone chart of the animal that divided the wolf up into fur zones; on the nose and the legs the hair was short and velvet, on the neck the mane was thick and long, belly clumped and long, the back more medium length while the tail was bushy. The coloring was not only unique over the length of the body, but the hair follicle had unique color ticking from root to tip.

    "Even with as far as computing power has come," said Fredenburg "it still is very difficult to accurately mimic real life, so everything we do to come up with our fur look is an approximation,
    a cheat. It's not about replicating a wolf hair for hair; it's about getting the feel of a wolf. Even though we pushed 4 million hairs on this show, which is
    twice what we normally grow, it is still not nearly the number of hairs a real wolf has."

    A real wolf would have hundreds of millions of hairs but a digital wolf will only have perhaps four million, so some interpretation is needed to achieve the same effect.

    To help achieve the fullness and fur realism needed, Aharon Bourland, Technical Art Director and Look Development, helped create Tippetts' in-house tool, Furator.

    New Moon was the second Tippett
    film where this tool was used. Similar
    to Shake in that is uses a tree-based system, it allows for characteristics
    of hair to be added via nodes, then merged back together for the final groom.

    It was developed to be highly flexible and extensible, such as the ability to twist a group of hairs from the tip and leave the base alone.

    Another very helpful addition was Scraggle, a tool that used a CV interp node that increased the number of CV's and resulted in a scraggled hair, then further adjusted so that the majority of scraggle was towards the base, creating the illusion of a thicker undercoat with smoother fur on top.

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  • The R&D team was moved to sit next to the painters so information could be shared quickly and deficiently. Since Furator is so new and constantly improving, the R&D department was instrumental with collaborating with the painters to make sure they were using the right parameters to get the job done and in the most efficient way.
    R&D was able to teach the paint how the tool was meant to be used and the painters, in turn, were able to teach the software developers how they wanted to use the tools.

    Wolf coloration is rather complicated due to the multiple color changes, not only across the body but down the length of the hair. A grey wolf might have dark roots and a white band in the middle and a brownish tip, yet add it all up and you have a salt and pepper look.

    To mimic this, Tippetts' texture painters painted three different sets of maps to dictate the color from the root to the tip of the fur.

    The painters had to achieve just the right amount of deep color to the fur without making it look too noisy or course, and the lighters had to maintain that detail but soften the fur so it had that nice plush feel.

    Painters painted maps and set numbers that stylized the hair, to clump, elevate, change the length, or randomize it to make it look more natural. Then they used imaged-based lighting to mimic the films overcast environments.

    Eyes and Face
    The book described the wolves as having eerily human eyes. "We were told early on that they literally they wanted us to plop the actors eyes into wolf, which always sounds like a good idea on paper but it does not work visually," said Fredenburg, "so we had to play how much to accentuate them as human eyes and how much to push them towards wolf eyes. The eyelid shape around them is definitely wolf. For the eyeball itself we tended to play a little bit dark so they wouldn't stick out as these funny white eyeballs in the head of the wolf." Wolf eyes are iconic and easily recognizable. They have a very distinct eye shape and mysterious expression. "As soon as we put the human eyes in that it destroyed that iconic wolf look, so we tended to play it as subtle as possible to keep from distracting from the wolf."

    With eyes, the surface quality is not hard to achieve but there's something intangible about eyes that is hard to get right. There are all kinds of subtleties that go into eyes that make them alive. The life in the eye comes from the way light plays on the eye when it's refracted through the lens. "It's not by mistake that people say they're windows to the soul. They're a focal point. There's a lot of unconscious stuff that we read from eyes that we still don't understand.

    Eyes are doing things we know and register? like we can read emotion on people through eyes? but if I were to try to draw a sad eye or an angry eye there's a subtly there that eyes can express that we cannot necessary see but just perceive, and that's very hard to get into CG."
    This was particularly challenging on one extreme close-up shot, as explained by Bourland.

    "We had to re-write our fur shader for this show. It was so close on the eye you could see individual hairs coming out of the skin. We had to write a new shader that would shade a cylinder so you could see each hair was rounded when you were close, but as you backed away it would shift to a flatter shading model, which worked better at a distance. It would use LOD (Level of Detail) to determine which shading model it was using, and transition between them as you pulled in and out. We also re-wrote the GI (Global Illumination) setup so it would solve on the hairs. Before it was too expensive to solve GI on the hair but we improved the fur shading so it would solve occlusion and color bounce on the individual hairs."

    Modeling and Animation
    At Wolf Mountain, the wolves were separated in different pens, some completely isolated, some in packs of three. In the packs there was generally an alpha, beta and omega. The characters in the book had the same sort of differentiation. Sam, the black wolf, was the Alpha and needed to be the largest wolf designed. Paul, the grey wolf was muscular, Embry was smaller. Jacob, the main character, had to stand out from the other wolves. To streamline the approval process of creating five distinct but similar wolves, the model for Jacob was used as the source asset for the other four wolves in a process that involved a technical rig for adjustments and natural pose for approvals, with a blend shape that could shift between the two. Character Supervisor Stephen Unterfranz explains: "Our rigs are broken into animation rig, the cut up geometry, the stiff parented geometry and then the deforming geometry, which we call the bound rig. One piggybacks on the other. We have a template file that contains all the model pieces and the skeleton and weighting with none of the rig, IK handles, etc, installed. Then we have a builder file that calls all the individual modules, the scripts that construct limbs and spines and eyes, and things like that. There is also a face rig that comes from model, primarily a blend shape rig that gets piped in to the full model also in this template file." This meant the one master wolf and rigging system could push out five wolves from one template when they were only updating master.
    Keep Your Shirt On
    The wolves also had to switch from human to wolf form and back again, creating some humorous situations. Tom Gibbons, Animation Supervisor, got a chuckle out of the young wolf shape-shifting process and the dilemma it created.

    They wanted to approach this in complete opposition to the way they did it in American Werewolf in London, which highlighted a long protracted painful metamorphose. In Twilight, it's very fast, it happens in half a second. "In the blink of an eye the boys explode into wolf forms. When you first become a werewolf, you are not very good at controlling it. What happens is, these kids explode into wolves and destroy their clothes and shoes, and when they transfer back, they don't have any clothes and have to go get more. It's kind of like hitting puberty or something, as these boys mature from human boys into shape shifting into werewolves and not being able to do it very well, which is the perfect metaphor for everything that is adolescent."

    There is a great deal of ribbing among the digital wolf pack as well as what was observed at Wolf Mountain. "That is exactly the way wolf packs work. There is a lot
    of rough and tumble challenging play fight all the time."

    Related Links

    New Moon
    Tippett Studio
    Tippett Studio New Moon site
    Tom Gibbons, Animation Supervisor
    Aharon Bourland, Technical Art Director, Look Development
    Nate Fredenburg, Art Director
    Stephen Unterfranz, Character Supervisor
    Wolf Mountain

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