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

Ronnie Schreiber
by Ronnie Schreiber

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

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4 of 12 comments
  • Texan01 Texan01 on Jul 06, 2012

    I thought they solved it years ago? the '86 Pontiac 6000-STE that I owned had bright yellow foglights from the factory. These coupled with the white headlights were awesome for actually illuminating the road in conditions that the regular headlights couldn't.

    • See 1 previous
    • Texan01 Texan01 on Jul 07, 2012

      @Spartan I've often considered replacing the useless auxiliary lamps on my Explorer with yellow fog lamps, but haven't looked all that hard for a good replacement for the stock location.

  • Danwat1234 Danwat1234 on Jul 09, 2012

    Well for now I think i'll stick with my plug and play 55watt 4500K HID kit. Very bright, works pretty well in the rain with halogen reflectors. Only cost $70 with a lifetime warranty.

  • 28-Cars-Later I'm actually surprised at this and not sure what to make of it. In recent memory Senator Biden has completely ignored an ecological disaster in Ohio, and then ignored a tragic fire in Hawaii until his handlers were goaded in sending him and his visit turned into it's own disaster, but we skipped nap time for this sh!t show? Seriously? We really are through the looking glass now, "votes" no longer matter (Hillary almost won being the worst presidential candidate since 1984 before he claimed the crown) and outside of Corvette nostalgia Joe doesn't care let alone know what day it happens to be. Could they really be afraid of Trump, who AFAIK has planned no appearance or run his mouth on this issue? Just doesn't make sense, granted this is Clown World so maybe its my fault for trying to find sense in a senseless act.
  • Tassos If you only changed your series to the CORRECT "Possibly Collectible, NOT Daily Driver, NOT Used car of the day", it would sound much more accurate AND TRUTHFUL.Now who would collect THIS heap of trash for whatever misguided reason, nostalgia for a much worse automotive era or whatever, is another question.
  • ToolGuy Price dropped $500 overnight. (Wait 10 more days and you might get it for free?)
  • Slavuta Must be all planned. Increase price of cars, urbanize, 15 minutes cities. Be poor, eat bugs
  • Sid SB Not seen a Core without the performance pack yet. Prefer the more understated look of the Core vs the Circuit, but both are great fun to drive.