3D Technology Images Flying Animals

A new multi-camera, real-time, three-dimensional method of recording multiple flying animals and insects shows the minutest details of these creatures.

In the future, the system may even be paired with virtual reality technology, allowing scientists to investigate every aspect of the behavior of airborne species, such as birds and houseflies. The new high-tech video package has been appropriately named "Flydra."

"The Flydra system uses high-speed cameras to track the 3D position of animals as they fly," project leader Andrew Straw, a senior research fellow in Computation and Neural Systems at the California Institute of Technology, told Discovery News.

"It does this almost instantaneously, so we know where the animal is at any given moment," added Straw.

In one set-up, Straw and his team combined 11 video cameras capable of recording around 60-100 frames per second. These were linked up to a network of nine standard Intel Pentium and Core 2 Duo computers. The system is described in the latest Journal of the Royal Society Interface.

Prior commercial motion capture systems, often used on blockbuster movies, required reflective markers. Straw said the markers are way too big and heavy to be stuck on a tiny fly. They're also impractical for use on big birds and other large animals. Flydra therefore eliminates that step.

Other earlier real-time 3D tracking systems could only record one or a few animals at a time. Flydra, on the other hand, can capture a limitless number, depending on how much the camera and computer set-up is expanded.

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So far, the researchers have determined that flies make decisions mid-flight based on basic visual rules.

"(The insects) fly towards tall vertical stripes and fly away from small blobs," Straw said. "Our best hypothesis for the relevance of this result is that this is a simple rule for effectively distinguishing between perch versus predator."

But the scientists aren't content on just performing rote experiments on flies with Flydra. They want to get inside the insect's head to completely figure this ubiquitous bug out.

"My big picture question is: How do flies perceive the world?" Straw explained. "By studying their flight trajectories in detail, and especially by giving them carefully designed experimental stimuli, we can reverse engineer algorithms they use. By performing genetic manipulations, we can reverse engineer what circuits are involved."

Mandyam Srinivasan, a professor of visual neuroscience at the Queensland Brain Institute, University of Queensland, told Discovery News that the new video system "is an important advance in the development of tools and techniques for simultaneously recording the motion of a number of objects -- animate or inanimate -- in three dimensions."

"It should find applications, for example, in tracking the detailed movement of all of the birds bird in a flock of birds, all of the horses in a race, all of the players in a cricket match, or of many, or all, of the bees in a bee swarm," Srinivasan said.

Mark Frye, a professor at UCLA's Department of Integrative Biology and Physiology, informed Discovery News that he is also impressed by the new system.

"This is a very sophisticated tool," Frye said. "No doubt the authors will themselves reap rich scientific rewards, but in the short term they have gone out of their way here to share their new method rather than hoarding future results. That is highly commendable."