Car Night Vision Systems
As you might imagine, the two auto moguls get from point A to point B in entirely separate ways. Mercedes-Benz uses an active system or near-IR system that illuminates the night with projected infrared light, much like optics found in military-issue night-vision goggles. BMW's passive system, on the other hand, uses far-IR or FIR technology in its onboard night-vision systems.
Unlike night-vision optics used for military applications, BMW's system registers images based on body heat and produces images that resemble a photo negative. While that works well for deciphering between animals and people, it doesn't do much for revealing a dead animal in the middle of the road or perhaps a large rock or a fallen tree. BMW's infrared system uses complementary metal oxide semiconductor (CMOS)-based sensors on the front of the car that pick up heat from objects and processes the thermal signature to display images on a quarter video graphics array (QVGA) display (320x240-pixel resolution) mounted on the dash in the center of the vehicle's console. In a nutshell, the BMW's system picks up the heat of the animal or pedestrian and displays it as a bright image. The warmer the target, the brighter the image displays. It has a range of around 980 feet (299 meters) and can pan in the direction the vehicle is heading. The FIR night vision system illuminates what's directly in front of the vehicle reasonably well, but doesn't offer the clarity found in the Mercedes system.
In contrast, the Mercedes system uses NIR technology and produces an even, clear picture in the dark. This system is similar to night-vision goggles soldiers use. Like the military-issued night-vision goggles, the NIR system in the Mercedes illuminates everything as if it were in the high beams of the vehicle. By utilizing a series of projection bulbs and cameras, the Mercedes' active night-vision system picks up the faintest traces of light and transforms it into a clear picture. The advantage is that the Mercedes system can see warmer living things just as clear as it can spot colder, dead animals or non-living objects. The drawback to the Mercedes system is its range: The system has a maximum effective range of less than 600 feet (183 meters). Another drawback is the Mercedes' NIR system doesn't handle fog well, while the BMW's FIR system can see through the dense conditions. But unlike the BMW's system, the Mercedes monitor is located behind the steering wheel, directly in the driver's line of sight to the road, and the image quality is also crisper on the NIR system.
Both systems can be turned on or off by the driver with controls found near the high-beam lever and neither system is affected by oncoming bright lights. Both are easy on the eyes too, so sensitivity to light should not be a problem for most drivers. Researchers from the two companies are also in the process of perfecting warning indicators on the night-vision systems. The challenge is to be able to decipher what's a hazard and what's merely a heat signature. The goal is for the systems to be able to set off an alarm when a pedestrian or animal is close enough to the road to be hazardous.
Both systems cost an extra $2,000 to $2,500. While that may sound like a significant amount of money, when you look at the price tag of a 7-Series BMW or S-Class Mercedes, two vehicles that can easily top $100,000, it somehow seems a bit more reasonable -- especially when you consider the benefit of being able to see through the darkness.
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- Akin, T. "CMOS-based Thermal Sensors." Middle East Technical University. Dec. 6, 2004. (Dec. 19, 2008) http://www.eee.metu.edu.tr/~tayfuna/BookChapter/CMOS-MEMS_Ch10.PDF
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