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A Horse Is A Horse Of Course...But Even In Motion Capture?

Motion capture takes a new direction when a live, four-legged creature is brought into the mix. Gregory Singer reports on capturing the motions of an Andalusian stallion.

People have been horsing around with animation techniques ever since the medium began. That's part of the fun of animating: discovering ways to make things work. Motion-capture, as a technique and tool for animating, is no different. There's still a lot of room for experimentation and discovery. Until recently, the technology of motion-capture has been used mostly for capturing human performances -- of martial arts, acrobatics, or subtle hand and facial gestures. Yet, there is a whole world of nonhuman personality waiting to be explored!

Rebollero in his motion-capture suit.© LocoMotion Studios.

Rebollero in his motion-capture suit.© LocoMotion Studios.

LocoMotion Studios of Wimberley, Texas is a unique and paradigmatic presence within the motion-capture industry. They have already begun to build a library of animal movements, for game development, multimedia and television projects. In one recent collaboration with Computed Animation Technology (CAT) of Dallas, the studio mocapped the data for a horse and rider, which was later used in FOX-TV's 1999 Halloween special, Night of the Headless Horseman. Where There Is A Will... The star of the mocap session was an eleven-year-old Andalusian stallion named Rebollero. Cared for from the age of one by a family of trainers dating back three generations, Rebollero regularly performs at Medieval Times, a restaurant in Dallas where an eleventh-century dinner and tournament are recreated, complete with jousting, nightly.

LocoMotion sets up the motion-capture session at Medieval Times. © LocoMotion Studios.

LocoMotion sets up the motion-capture session at Medieval Times. © LocoMotion Studios.

For the capture session, which was held in the arena at Medieval Times, LocoMotion and CAT merged their two Vicon 8 systems, using a total of 18 cameras to expand their capture volume. The Vicon data station was hung 30 feet off the arena floor from an overhead light grid, along with several other cameras. The remaining cameras were arranged around the perimeter of the arena, approximately 15 to 18 feet above the floor.

One of the greatest challenges of capturing any animal movement -- which can be forceful and unpredictable -- is trying to figure out how to place markers on the animal. There had been some previous work done in England, by a different studio, where patches of the horse's skin were shaved, shot with novacaine (to dull the skin's feeling) and then the markers were superglued to the animal.

For obvious ethical reasons, this wasn't an option for LocoMotion. Instead, initially, the crew experimented with using veterinary glue to affix the markers directly on to the horse's skin. But it turned out that the glue was uncomfortable for Rebollero. He would sweat and dissolve the glue, or his muscles would twitch and shake the markers off. Eventually, LocoMotion designed and made a custom-fitted Lycra suit with Velcro patches to hold the markers. At first, the technicians were concerned that the suit might overheat Rebollero. However, since he was already accustomed to wearing costumes for the Medieval Times shows, he didn't seem bothered at all. When everything was finally in place, Rebollero was wearing about 40 markers, and the rider 32. There were no occlusion problems; the animators were able to distinguish easily between the horse and rider data. Once the general movement was established, tweaking and fine-tuning of the key frames would achieve the desired look.

More Than Meets The Eye

Kei Taniguchi, marketing director of LocoMotion, explains the benefit of capturing this kind of data: "We have an idea of how animals walk, but not completely. It is something that doesn't always get articulated in hand-drawn animation. There are a lot of nuances of movement; the action of the hoof, for example -- its dynamics and flex. There's a lot more going on down there than we originally thought."

The star got the knack of the new technology quite quickly. © LocoMotion Studios.

The star got the knack of the new technology quite quickly. © LocoMotion Studios.

To expand their library, LocoMotion will probably coordinate more capture sessions with Rebollero. They still want to capture more running cycles, and for that, they will need a longer capture volume. The original venue was only 40 feet long, and Rebollero was just too fast for that space. While his first performance provided a decent run cycle, they could only capture one or two strides of what would ideally be a longer, fully extended sprint sequence. In addition, there are a lot of smaller horse movements that people don't generally think about, but which definitely contribute to his personality, like ears flicking, head looking around, tail whipping, etc. Taniguchi explains that in future sessions, they may concentrate on some close-ups of Rebollero to capture references for the ears, mane and tail. "We did one capture of him just standing there and another one of him grazing. At first, he wasn't quite sure what everyone wanted him to do -- which, of course, was nothing. But after a few minutes, his trainer walked away, and he figured it out."

The finished product from Night of the Headless Horseman. Courtesy of and © Computed Animation Technology (CAT),Dallas, Texas.

The finished product from Night of the Headless Horseman. Courtesy of and © Computed Animation Technology (CAT),Dallas, Texas.

LocoMotion has already received requests for other projects. Based on the needs of their customers, they are now planning to capture such animal movements as those of large cats and guard dogs -- among other top-secret, hush-hush kinds of work. Given the time and budget constraints of any production (and the efficacy of motion-capture in streamlining and refining the process), what more could a studio wish for? With a laugh, Taniguchi admits: "Everyone [at LocoMotion] now really appreciates working with humans. It's so easy compared to doing a horse!" Gregory Singer grew up in Maryland and studied biology there. After a tour of service in the Peace Corps in Kenya, he finally wandered his way to Los Angeles, where he is presently a graduate student of film producing at Chapman University. Mr. Singer is also the assistant editor of the Animation Journal, a peer-reviewed scholarly journal devoted to animation history and theory.

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