Carnegie Mellon Researchers Invent Smart Headlights That "See Through" Rain, Snow

The problem with driving at night in the raining or snowing conditions is that your headlights work too well. They light up the rain and snow as much as they illuminate the road ahead, sometimes more so. In a novel approach using cameras, computers and DLP projectors to replace conventional headlight bulbs, researchers at Carnegie Mellon University have developed a “smart” headlight system that essentially shines light between the rain drops.

It turns out that less really can be more, at least in terms of night driving. By selectively reducing the amount of light projected, by not shining light on the computer predicted path of the rain drops or snow flakes as they enter the critical 3-5 meter space in front of the driver, there is significantly reduced glare.

Theoretically in a perfect system with minimal latency, illuminating 100% of rain drops would come at a cost of only a 2% reduction in total light projected. Precipitation is only a small fraction of the total visual field. So far in lab tests with real water drops falling at normal precipitation levels and slow (30KPH) travel speeds, they can reduce the visibility of rain almost 70% at a cost of only 5% loss of light. The system is less efficient with snowflakes, because they are larger and move more slowly, so there’s about about 15% loss of light, but it can still keep from illuminating more than 60% of the snow. At higher speeds it’s less efficient but lead researcher Srinivasa Narasimhan says that continued development for highway speed use is worthwhile, while stressing that the current system cannot account for wind, turbulence and that it needs to be more compact. Though the researchers stress the data capture and processing parts of the system, it couldn’t work without a DLP projector, one of our age’s unappreciated wonders. The microminiature mirror array in a DLP device can be precisely controlled as to where it shines light.

Ronnie Schreiber edits Cars In Depth, a realistic perspective on cars & car culture and the original 3D car site. If you found this post worthwhile, you can dig deeper at Cars In Depth. If the 3D thing freaks you out, don’t worry, all the photo and video players in use at the site have mono options. Thanks for reading– RJS