Smart headlights: Rain or snow, drive sans glare scare

BANGALORE, INDIA: Srinvasa Narsimhan, Associate Professor, Computer Science, at Carnegie Mellon University's Robotic Institute, claims his group has invented Smart Headlights which can make rain or snow almost disappear, or look like a light drizzle. Obviously this would greatly improve the visibility and help the drivers avoid accidents.

We all have seen how light tends to get diffused, the beam of light hits the water droplets and some get reflected back at us, making us dazed.

The new system uses very high speed cameras and an algorithm to predict where the raindrops will fall and also when a rain drop would hit the path of a very precise beam of one of the individual mini-lights.

As soon as that happens, the system, for a split second, flicks the beam off. This causes a major reduction in the glare which bothers the drivers so much. The system is designed in such a manner that the flickering being too short, is not perceived by the human eye. As the individual rain or snow particles are not being lighted up, they aren't registered on the human eye either.

Narasimhan and team, checked if they could stream light in between the drops. Their answer consists of a co-located imaging and illumination system-- camera, projector, and beam-splitter.

The idea is to integrate an imager and processing unit with a light source. The beam-splitter (50/50) permits optically co-locating the camera and projector to eliminate the need for stereo reconstruction, reducing computations and increasing system speed.

The camera images the precipitation at the top of the field of view. The processor can tell, using the specially-developed algorithm, where the drops are headed and sends a signal to the headlights, which make their adjustments and react to dis-illuminate the particles.

In other words, there is no time for the light to get reflected back to the human eye. The entire action, starting from capture to reaction, takes about 13ms. (The system runs at 120Hz. The camera uses a 5ms exposure time and the system has a total latency of 13ms.)

Why it works, is mainly due to this time lag, before the reflection can occur, the light has been flicked off, and the rain drop passes quickly down to earth.

The system's operating range is about 13 feet in front of the headlights. The team claims that in contrast to recent computer vision methods that digitally remove rain and snow streaks from captured images, this system will directly improve driver visibility by controlling illumination in response to detected precipitation.

The motion of precipitation is tracked and only the space around particles is illuminated using fast dynamic control. Computer simulations show that a system operating near 1,000Hz, with a total system latency of 1.5ms, and exposure time of 1ms can achieve 96.8 pc accuracy with 90 pc light throughout during a heavy rainstorm (25mm/hr) on a vehicle travelling at 30km/hr.

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Video at: http://bit.ly/THpdJt

Max Babi is a metallurgist and tech enthusiast.

(The views expressed by the author are his own and not of CIOL)