Night Vision Systems
Night vision helps drivers see people or animals in the distance at night. It generates a video image in real time in either the heads-up display or on a monitor in the instrument panel. The potential safety advantage of Night Vision systems is in facilitating earlier detection of objects compared to headlamps alone. These systems use infrared sensors to detect heat contrasts.
There are basically two technologies, near-infrared (active system) and far-infrared (passive system).
The near-infrared system emits infrared light to illuminate the road and objects ahead; a camera captures the reflected radiation and this signal is then processed by the computer which produces a black-and-white image that is projected onto the windshield. This type of system provides a higher resolution image and clearer picture of cold objects (such as large rocks or dead animals) and works better in warmer conditions than the far-infrared system. It does not work well in fog and has a lower contrast for animals.
The far-infrared system detects the heat emitted by objects and uses algorithms to process the images with warmer objects appearing brighter. The visual display looks similar to a photo negative.
Some systems alert the driver with an audible alarm when it detects a pedestrian.
- These systems operate when the headlights are turned on.
- Some systems can detect people or animals at 150 metres and others up to 300 metres.
Things to keep in mind
- Night vision is an aid to headlights. Do not rely on it alone to detect people or animals
- Display monitors can distract the driver. Drivers must focus on driving and take only occasional glances at the night vision display.
- The hotter the source, the better the detection
- System performance is limited on hot days
- The systems require a heat contrast of 10 deg C to detect people or animals.
- Street or sign lighting can make it more difficult for the system to identify people or animals
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