This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American
U.S. swimmer Dana Vollmer's record-setting performance in London in the 100-meter butterfly is sure to be a model for aspiring Olympians. Vollmer's edge in butterfly competition comes from her uncanny ability to closely mimic the underwater undulation and kick of nature's greatest swimmer—the dolphin.
The 24-year-old Syracuse, N.Y., native worked with a team of motion-capture video specialists from New York University (N.Y.U.) prior to the 2012 Olympic Games to analyze her kick, grab and recovery as she cuts through the water and found the similarities striking. N.Y.U. computer scientist Chris Bregler and his team applied black-and-white markers to Vollmer's body so their AquaCap underwater motion-capture system could gather three-dimensional data that would allow them to digitally reconstruct her stroke and compare it with that of a dolphin (see video below).
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At N.Y.U.'s Movement Lab Bregler has been using motion-capture technology to help law enforcement, professional athletes and entertainers study a wide variety of movement. Subjects have included New York Yankees baseball pitcher Mariano Rivera and New York Philharmonic's conductor Alan Gilbert.
Vollmer's waterproof black-and-white markers—somewhat similar to decals that carmakers place on crash-test dummies to track their movement upon impact—provided stark contrast that was easier for the camera to pick up. "These patterns can be used to track with high accuracy in high-speed cameras the center of the patch, even if its motion is blurred," Bregler says.
Typically, motion-capture relies on reflective bulb-like markers placed at various locations on a special motion-capture suit. This was a less appealing option when trying to visualize a streamlined swimming stroke in a pool, where other reflections are already abundant.
As Scientific American learned last year, light reflected from these markers is picked up by an array of cameras capturing video of the motion-capture subject from a variety of different angles. Software gathers the data collected from the reflectors and maps the location of each marker on a computer screen.
For additional analysis of the Olympic Games and how science comes into play, check out Scientific American's eBook The Science of Sports: Winning in the Olympics.
Images courtesy of N.Y.U./Manhattan Mocap LLC