Researchers from MIT have succeeded in exploiting the polarisation of light to make the images produced by regular 3D scanners 1,000 times better than they are today. This could make high-resolution 3D cameras in smartphones a possibility and improve cameras in driverless cars during bad weather.
At the moment, cheap 3D scanners in some phones can somewhat get the job done, but they still miss out on details.
"Today, they can miniaturise 3D cameras to fit on cellphones, but they make compromises to the 3D sensing, leading to very coarse recovery of geometry. That’s a natural application for polarisation, because you can still use a low-quality sensor, and adding a polarising filter gives you something that’s better than many machine shop laser scanners," said Achuta Kadambi, a PhD student in the MIT Media Lab and one of the system’s developers.
The physical phenomena of light polarisation affects the way in which light bounces off physical objects. Reflected light behaves in a different way from regular light, which scatters in all directions.
If light strikes an object squarely, most of the light will be absorbed, but when sunlight bounces off water or asphalt, there is an unusually heavy concentration of light with a particular polarisation, and the reflected light travels in a horizontally-oriented direction, which can be dangerous in its intensity.
This is why sports enthusiasts and fisherman wear polarised sunglasses, the glasses contain a filter that blocks intense reflected light of a certain polarisation, which reduces glare to protect your eyes and help you to see better.
The ideal 3D scanner would work by taking measurements of polarised light, and then looking at all the possible combinations of two equally plausible hypotheses to determine the orientation of the object based on what makes the most sense geometrically, but this would take a very long time to compute.
So the researchers decided to solve this problem by creating computer algorithms that make coarse depth estimates based on other methods, such as the time taken for the light signal to reflect off an object and return to its source.
The invention could also be used to make smartphone cameras that are so high in resolution that they could take a photo of an image and then send it directly to a 3D printer to be printed out.