Sharper 3-D Laser Scanner Impervious to Ambient Light

Refining principles of 3-D sensing for video games, researchers at Northwestern University have developed a 3-D laser scanner that produces detailed moving images even in the presence of bright ambient light.

The device is modeled after the human eye, and only scans parts of the scenes that have changed, making it much faster and higher quality than other similar systems.

"If you send the same signal to your eye over and over, the neurons will actually stop firing," said Oliver Cossairt, an assistant professor of electrical engineering and computer science at Northwestern’s McCormick School of Engineering. "The neurons only fire if there is a change in your visual stimulus. We realized this principle could be really useful for a 3-D scanning system."

Microsoft's Kinect device for its Xbox video game systems works by projecting light patterns that are then sensed and processed to estimate scene depth at each pixel on the sensor. Although these techniques work quickly, they are less precise than more expensive single-point scanners.

The Kinect is also limited in that it does not work well outside because sunlight overpowers its projected light patterns. The laser on Cossairt’s camera, however, can be sensed in the presence of sunlight because it is much brighter than ambient light.

"In order for a 3-D camera to be useful, it has to be something you can use in everyday, normal environments," Cossairt said. "Outdoors is a part of that, and that’s something the Kinect cannot do, but our Motion Contrast 3-D scanner can."

The device has many applications for devices in science and industry that rely on capturing the 3-D shapes of scenes "in the wild," Cossairt said, such as in robotics, bioinformatics, augmented reality and automated manufacturing. It could also be used for navigation, installed on anything from a car to a motorized wheelchair.

Cossairt’s group received a Google Faculty Research Award to integrate their 3-D scanning technology onto an autonomous vehicle platform. Additional funding came from the Office of Naval Research and the U.S. Department of Energy.

The research was presented recently at the IEEE International Conference on Computational Photography.

For more information, visit www.mccormick.northwestern.edu.