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Mercredi, 14 Décembre 2011 18:43

Scientists Hack Kinect to Study Glaciers and Asteroids

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Scientists Hack Kinect to Study Glaciers and Asteroids

SAN FRANCISCO — Last summer, Ken Mankoff shimmied through zero degree water and mud into a small cavern underneath Rieperbreen Glacier in Svalbard, Norway, holding a Microsoft Kinect wrapped inside a waterproof bag.

Using the little toy, originally meant as a motion-sensing device for the Xbox 360 video game console, Mankoff scanned the cave floor in 3D. During the summer, water from lakes on the glacier’s surface had gushed through the channel he was sitting in. The Kinect was going to provide a better understanding of its size and roughness, which could help researchers predict how the ice above would flow toward the sea.

“I’ve always enjoyed repurposing cheap devices, doing things that you’re not supposed to do with them,” said Mankoff, a NASA funded Ph.D. student at the University of California, Santa Cruz studying ice and ocean interactions. “You know, the hacker ideals.”

He is currently a bit of an evangelist for the Kinect, trying to get scientist interested in using the device, which can record very accurate 3D data in visible and infrared wavelengths. As part of this, he presented a poster of his work here Dec. 8 at the American Geophysical Union meeting in San Francisco. The poster drew strong crowds and piqued the interest of at least a dozen researchers.

At prior AGU conferences, scientists demonstrated the potential for Nintendo’s Wiimote as a scientific tool. While the single-point Wiimote measurements are useful, Mankoff said that the Kinect is on another level, with nine million data points per second.

Right now, most researchers employ a technology called Light Detection and Ranging (LIDAR), which uses laser pulses to accurately map large areas over many miles. Though a Kinect can only see between three and 16 feet ahead, it has the enormous advantage of costing $120, compared to between $10,000 and $200,000 for a LIDAR setup.

“You can go in any store and buy a Kinect for a small price,” said hydrologist Marco Tedesco of the City College of New York, whose research involves remote sensing on glaciers. “You can even crash it and then buy another one.”

LIDAR instruments also suffer the drawback of having to be ordered, calibrated, and repaired from specialized distributors, while the Kinect has readily available open-source drivers, he added.

Tedesco is interested in mounting a lightweight Kinect to a small remote-controlled helicopter or boat and mapping the meltwater lakes that form atop glaciers in the summer. Such lakes can be one to two miles wide and more than 30 feet deep, and are often suddenly drained when large cracks appear in the glacier, depleting the lake in as little as an hour. This water lifts the ice sheet and acts as a lubricant on the ground, accelerating the glacier toward the ocean.

“The more water you have the more violent this process is,” said Tedesco, who hopes to use the Kinect to get better estimates of the lake volumes by measuring the shoreline when they are full and scanning the bottom once they are empty.

Far from the ice, Naor Movshovitz is interested in using the technology to get better information on impacting small bodies in outer space. Movshovitz, a planetary science Ph.D. student at UC Santa Cruz, said this data would be useful for future missions that may have to deflect medium to large asteroids that threaten to hit Earth.

Researchers have a relatively good understanding of how impact craters form on large bodies such as Earth or Mars. The question is how such processes scale down to asteroids, where the surface gravity may be only one-thousandth that of Earth.

Movshovitz envisions a mission that would gather asteroid-like gravel and place it aboard one of NASA’s gravity reduced aircraft — planes that fly in steep dives and climbs to simulate zero-g conditions. Within the plane, the materials would also be enclosed inside a centrifuge, so that researchers could impart a very small amount of gravity to the gravel, and then send a projectile to impact the dirt pile.

The Kinect’s ability to measure the three-dimensional position of objects would allow Movshovitz to get data about the flight of each pebble after the projectile’s impact. At least three separate cameras and advanced image processing software would be needed to get the same information, while the Kinect has everything in a simple, ready-to-use package.

Despite its many potential uses, the device has shortcomings. Ideally, Movshovitz would like to get very high-speed video of his micro-g flying gravel, but the Kinect can’t do high-speed video.

Another main problem is how to bring something that was designed for use in a living room out into the field, where it will have to deal with environmental factors such as moisture and temperature extremes.

The Kinect has trouble recording accurately through a lens of any kind, making it difficult to provide it with adequate shelter against the elements, said glaciologist Bob Hawley from Dartmouth College in Hanover, New Hampshire, who would like to use the device to create time lapse movies of melting ice sheets. But Hawley is sure that researchers can find ways.

“We’ll put the Kinect through its paces in the lab to make sure it’s up to snuff,” he said.

The Kinect’s best asset may be that it inspires students, Tedesco said. Rather than a daunting black box with convoluted cables and arcane software, the Kinect is something that many students are already familiar with.

“This creates a different mindset in students,” he said. “They’re not so scared about using the Kinect, and they can really get involved in learning and basic research.”

“I’m actually on my way to buy two of them right now,” he added.

Scientists Hack Kinect to Study Glaciers and Asteroids

Images: 1) Subglacial cave underneath Rieperbreen Glacier, Svalbard, Norway with Mankoff, waterproof bag, Netbook running Ubuntu, and Kinect. Jason Gulley. 2) A sample of the 3D data from the Kinect’s scan of the glacier cave. Ken Mankoff.


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