What is Automotive Night Vision?

passive automotive night vision
Passive automotive night vision turns a thermal image into a black and white image.

Robert Basic / Flickr / CC BY 2.0

The catch-all term of automotive night vision refers to a number of loosely related technologies that can that help increase situational awareness when low light conditions make it difficult to see the road.

These systems basically extend the perception of the driver beyond the limited reach of headlights through the use of thermographic cameras, infrared lights, heads up displays, and other technologies.

Since automotive night vision can alert drivers to the presence of potential hazards before they become visible, these systems can help prevent accidents.

How Does Night Vision Work in Cars?

Automotive night vision systems are broken into two basic categories, which are referred to as active and passive. Passive night vision systems use thermal cameras that are capable of picking up the heat that radiates from objects, animals, and people, and active systems use infrared light sources to illuminate the darkness.

Both active and passive night vision systems rely on the infrared light spectrum that we can't see with the naked eye, and each one has its own benefits and drawbacks.

Passive Automotive Night Vision Systems

Passive night vision systems rely on thermographic cameras to detect thermal radiation. Since thermographic cameras essentially see heat, it's easy for them to pick out the difference between a warm object, like a person, and a cooler object like a road.

Data from the thermal cameras used in passive systems is typically processed into a black and white image that provides the driver with an enhanced view of the road ahead.

Due to the reliance on heat emissions, passive systems tend to work very well with people, animals, and other vehicles, since they all emit a lot of thermal radiation.

The drawback of passive systems is that they have trouble picking up inanimate objects that are about the same temperature as the surrounding environment.

The range of passive night vision tends to be significantly higher than the range of active night vision, which is due to the limited power of the light sources used by the latter systems. However, the image quality produced by the thermographic cameras tends to be poor when compared to active systems, and they don’t work as well in warm weather since an increase in the ambient temperature will naturally cause normally cool objects, like road surfaces, to warm up during the day and then radiate heat after the sun goes down..

Active Automotive Night Vision Systems

Active systems are more complex than passive systems because they use infrared light sources. Since the infrared band falls outside the visible spectrum, these light sources don’t cause oncoming drivers to suffer from temporary night blindness like high beam headlights can. That allows the infrared lights to illuminate objects that are significantly further away than headlights are able to reach.

Since infrared light isn’t visible to the human eye, active night vision systems use special cameras to relay the extra visual data. Some systems use pulsed infrared lights, and others use a constant light source. These systems don’t work very well in adverse weather conditions, like heavy snow and hail, which can partially block the infrared light source. However, they do typically provide high contrast images of vehicles, animals, and even inanimate objects.

How Does Infrared or Thermographic Information Help You See?

There are a number of types of night vision displays that can relay infrared or thermographic information to the driver. The earliest night vision systems used heads up displays, which projected warnings and alerts on the windshield within the driver’s field of vision. Other systems use an LCD that's mounted on the dash, in the instrument cluster, or integrated into the head unit.

What Vehicles Have Night Vision Systems?

Automotive night vision systems have been around since 1988, but they are still found primarily in luxury vehicles. The technology is typically optional equipment, and it can be quite expensive. The first night vision systems were introduced by GM, but a number of other automakers now have their own versions of the technology.

Mercedes, Toyota, and Toyota’s Lexus badge all offer active systems. Other automakers, such as Audi, BMW, and Honda, offer passive options. General Motor's Cadillac badge also offered a passive night vision system, but the option was discontinued in 2004.

There are also a number of systems available in the aftermarket.

Does Night Vision Really Help Reduce Accidents?

According to the European Commission for the Automobile Industry, nearly 50 percent of all accidents occur at night. Since the same study showed about 60 percent less traffic at night, it’s clear that a disproportionate number of accidents occur between dusk and dawn.

Since night vision isn’t widely available, there is no conclusive data to say definitively whether or not night vision systems actually help. A study performed by the National Highway Transportation Safety Administration even revealed that some people are willing to drive faster at night with the aid of these systems, which could lead to more accidents.

However, other technologies that increase nighttime visibility have been shown to reduce accidents. Since technologies like adaptive headlights have helped reduce nighttime accidents, it’s possible that wider adoption of night vision could have similar effects.

Night vision systems can detect objects that are more than 500 feet away, but traditional headlights typically only illuminate objects that are about 180 feet away. Since the stopping distance of a car can easily be longer than 180 feet, it’s clear that the proper use of a night vision system can help an alert driver avoid certain collisions.