Images courtesy of Carnegie Mellon University
Microsoft’s Kinect controller for video games, known as depth-sensing cameras, have widely used 3D sensors. Now, a new imaging technology invented by researchers at Carnegie Mellon University and here in the Department of Computer Science, addresses a major shortcoming of these cameras: the inability to work in bright light, especially sunlight. The researchers presented their findings at SIGGRAPH 2015, the International Conference on Computer Graphics and Interactive Techniques, in Los Angeles.
The problem is that these devices use compact projectors that operate at low power, so their faint patterns are washed out and undetectable when the camera captures ambient light from a scene. But as a projector scans a laser across the scene, the spots illuminated by the laser beam are brighter, if only briefly.
“Even though we’re not sending a huge amount of photons, at short time scales, we’re sending a lot more energy to that spot than the energy sent by the sun,” said Professor Kyros Kutulakos. The trick is to be able to record only the light from that spot as it is illuminated, rather than try to pick out the spot from the entire bright scene.
The prototype uses a rolling-shutter camera, this is accomplished by synchronizing the projector so that as the laser scans a particular plane, the camera accepts light only from that plane. Alternatively, if other camera hardware is used, the mathematical framework developed by the team can compute energy-efficient codes that optimize the amount of energy that reaches the camera.
The new approach also could be used for medical imaging, such as skin structures that otherwise would be obscured when light diffuses as it enters the skin. Likewise, the system can see through smoke despite the light scattering that usually makes it impenetrable to cameras. Manufacturers also could use the system to look for anomalies in shiny or mirrored components, and so the possibilities extend to space exploration.
In addition to Professor Kutulakos and Srinivasa Narasimhan, CMU associate professor of robotics, the research team included Supreeth Achar, a CMU PhD student in robotics, and U of T PhD student in computer science, Matthew O’Toole.
The research was supported by the National Science Foundation, the U.S. Army Research Laboratory, and the Natural Sciences and Engineering Research Council of Canada.
– Express Computer India