Animators provide a frighteningly close look at a tick as it feeds
By Jenny Donelan
A personal encounter with a deer tick inspired animator Bill Mat thews to create a virtual version of the tiny parasite in action. While hiking the Appa lachian Trail in Connecticut several years ago, Matthews was bitten by Ixodes scapularis and subsequently developed Lyme disease, the inflammatory malady caused by a bacterium for which the tick is a carrier.
Because deer ticks are hard to spot-they can be as small as a poppy seed-"I never saw the tick that bit me," says Matthews (who has since recovered). But he became intrigued by the idea of modeling and animating a deer tick in Alias|Wavefront's (Tor onto) Maya to highlight the capabilities of Life House Productions, the Wallingford, Connecticut-based biomedical animation house he owns with partner Dena Wink leman. The end result-a short but arresting tick's-eye view of the creature plunging its mouth parts into the skin of a human host-earned the firm an Award of Excellence at the most recent Rx Club Show, an an nual worldwide com petition hon oring medical advertising and graphics.
|Before creating the final detailed, textured version of the deer tick in Alias|Wavefront's Maya, LifeHouse animators made a simplified proto-tick, at right, also in Maya, in order to work out the creature's movements with a smaller and less complex model.|
Before they could embark on the task of modeling and animating a deer tick, the artists at LifeHouse had to find out what one looked like and how it moved. They researched ticks and Lyme disease, and also found real deer ticks in the field-"actually, they kind of found us," says Matthews-and refrigerated them for later study.
Matthews also paid visits to the nearby Connecticut Agricultural Experiment Station in New Haven, where tick expert Dr. Kirby Stafford III helped them view the creatures under a powerful mic roscope. "He put one on something called a freeze plate," says Mat thews, "which gets very cold and slows down the tick's crawling, so you can watch it under the microscope without it going out of view really fast."
Looking at live ticks in slow motion helped Matthews achieve his goal of creating as realistic an organism as possible. "When you look at pictures in books or at dead ticks, you don't see certain things," he says. He learned, for example, that although ticks have eight legs, they usually walk on six. "Dr. Stafford pointed out that when the tick walks, the front two legs are usually held up in the air, like feelers or sensors."
Since the team planned to have the animated tick come face to face with the viewer, Matthews had to study real ticks from this perspective, which proved difficult. "We'd have the tick on a stick, but every time we turned or lifted the stick, he'd crawl the other way." Eventually, the team got additional help from the Rhode Island Tick Pickers (a research group affiliated with the University of Rhode Island), which provided some additional imagery, including powerful magnifications of the tick's tiny, all-but-invisible feet.
|Snout deep in its host, a virtual tick offers a rare look at its species' dining habits.|
Once the team members had an idea of what the tick should look like, they had to make it move realistically. Using Maya running on a Dell (Round Rock, TX) Di mension 610 NT workstation, the team built a sort of proto-tick with a ball for a body and blocks for legs. Sorting out the proper movements was easier with this simplified model than it would have been using a large textured model, but even so, "I think it took over a week just to get the legs working right," says Matthews.
Then the animators created a more photorealistic tick, also in Maya, but with texture maps created in Adobe Systems' (San Jose, CA) Photoshop applied to the legs and different parts of the body. This model included the tiny claws, transparent joints, orange-red color, and other surprising details of the actual item. With the naked eye, for example, "You don't ordinarily see the orange color," says Winkleman, "because the bug is so tiny that you just see it as little and dark."
Where necessary, the team enhanced reality slightly. "The legs," says Mat thews "are probably a little blacker [than in actuality] because we were afraid that otherwise they wouldn't show up in the video."
To create the surface over which the tick moves, Matthews shot a close-up of human skin and converted it to a 1020x1020 color texture map. Then, using Photoshop, he turned the texture map into a grayscale image to use as a bump map and also as a displacement map. In Maya, he laid the bump map texture over the displacement texture map to achieve the look he wanted.
One of the greatest challenges the team faced was keeping the tick's feet from going through the skin as it walked. After they built the skin, they first simply slid the tick over the surface to work out the timing and the camera angles, and to make sure the creature didn't bump into or penetrate any of the hairs growing forest-like around it. "Then," says Matthews, "we came back in and did the kinematics on the feet."
In the final version of the animation, the skin sinks slightly under each of the tick's footsteps, which the team accomplished using the sculpt deformer tool in Maya. "The tick would move along and we would adjust the geometry of the skin so that it looked as if his foot was pushing the skin down, and we made it come down faster than it came back up, so that it would appear as if fluid were coming back into the skin to fill the dimple where he had walked."
|Animator Bill Matthews, a former medical photographer, shot close-ups of human skin as the basis for the surface over which the tick walks. |
The team then animated the sky in Maya, and used Adobe Systems' After Effects for compositing. "I think the project had something like 19 layers in it-the sky, different hairs, some of the blurred layers we used for when you first see the tick in the distance," says Matthews.
The completed animation begins with what looks like a tarantula scrabbling through grass. As the "tarantula" comes closer, it takes on more of the appearance of a flat-bodied tick. To an ever-louder techno-industrial beat, the tick comes closer and closer, until, confronting the viewer, it raises its gray, masklike head, then plunges its snout (looking like nothing so much as the business end of a chainsaw) into the host's skin.
"We gave the tick a little bit of [a menacing] character," says Matthews. The animators hope the film will convince anyone who sees it to take preventive measures against deer tick bites. "What we wanted to do," says Matthews, "was capture somebody's emotion...to, as Dena says, 'creep them out.' "
The tick's creators say they have spoken with pharmaceutical companies re garding the use of the tick, or perhaps a revised version of it, but could not confirm any agreements at this time. In any case the animation makes a convincing argument for using insect repellent or wearing long pants when walking in the woods-or maybe even just staying safely at home.
Key Tool Maya, Alias|Wavefront, www.aw.sgi.com