Researchers at the Massachusetts Institute of Technology combined Microsoft Kinect 3D imaging data with polarized photographs in order to increase resolution 1,000-fold [mit.edu]:
MIT researchers have shown that by exploiting the polarization of light — the physical phenomenon behind polarized sunglasses and most 3-D movie systems — they can increase the resolution of conventional 3-D imaging devices as much as 1,000 times. The technique could lead to high-quality 3-D cameras built into cellphones, and perhaps to the ability to snap a photo of an object and then use a 3-D printer to produce a replica. Further out, the work could also abet the development of driverless cars.
"Today, they can miniaturize 3-D cameras to fit on cellphones," says Achuta Kadambi, a PhD student in the MIT Media Lab and one of the system's developers. "But they make compromises to the 3-D sensing, leading to very coarse recovery of geometry. That's a natural application for polarization, because you can still use a low-quality sensor, and adding a polarizing filter gives you something that's better than many machine-shop laser scanners."
The researchers describe the new system, which they call Polarized 3D, in a paper they're presenting at the International Conference on Computer Vision in December. Kadambi is the first author, and he's joined by his thesis advisor, Ramesh Raskar, associate professor of media arts and sciences in the MIT Media Lab; Boxin Shi, who was a postdoc in Raskar's group and is now a research fellow at the Rapid-Rich Object Search Lab; and Vage Taamazyan, a master's student at the Skolkovo Institute of Science and Technology in Russia, which MIT helped found in 2011.
[...] The researchers' experimental setup consisted of a Microsoft Kinect — which gauges depth using reflection time — with an ordinary polarizing photographic lens placed in front of its camera. In each experiment, the researchers took three photos of an object, rotating the polarizing filter each time, and their algorithms compared the light intensities of the resulting images. On its own, at a distance of several meters, the Kinect can resolve physical features as small as a centimeter or so across. But with the addition of the polarization information, the researchers' system could resolve features in the range of tens of micrometers, or one-thousandth the size. For comparison, the researchers also imaged several of their test objects with a high-precision laser scanner, which requires that the object be inserted into the scanner bed. Polarized 3D still offered the higher resolution.
Polarized 3D: High-Quality Depth Sensing with Polarization Cues [mit.edu]