Press Release
A comparison of night vision technologies
Far Infrared (FIR) vs. Near Infrared (NIR)
Night vision: two differing technologies on the market.
Night vision devices for military and civilian use have existed for some time. There are currently two different technologies: Near Infrared (NIR) and Far Infrared (FIR). NIR and FIR are initially distinguished by the technological process by which they register the area in front of the vehicle and convert this into image information for the driver:
· Near Infrared NIR beams an infrared light source into the area in front of the vehicle. The light is reflected by objects, the road and human beings and photographed by an infrared camera. This is then converted to an image in the processor and displayed on a screen.
· With Far Infrared FIR, a thermal imaging camera directly registers the heat radiated by objects and human beings, making a separate light source from the vehicle superfluous. This information is then also converted by a processor into an image and displayed on the screen.
FIR better suited for use in automobiles.
The two technologies are distinguished mainly in the method by which they visualise information from the surroundings on the screen. With BMW Night Vision, BMW opted for a further developed system based on FIR technology. Here, after intensive system comparisons and direct comparative studies, the choice fell to FIR since this system best performs the function of detecting human beings and objects in the dark early on. FIR concentrates on the most important information and manages without distracting details.
Advantages for FIR based on technological principles.
The BMW technicians first recognised advantages based on the technological principles of the system. For example, the range of night vision systems based on FIR surpasses the other technologies by up to 200 per cent, with NIR essentially only accounting for the area already covered by a conventional high beam. Due to the strong heat radiation from people (pedestrians, cyclists) and animals (wild animals crossing the road) as compared to other objects (buildings, traffic, road signs etc), the thermal image reflects the potentially more dangerous situations on the road – i.e. exactly those points which BMW Night Vision aims to draw the driver’s attention to. At the interface to the driver, the symbolic depiction of the thermal image on the monitor represents a reduction of the total information and thus a further emphasis on the potentially critical points.
BMW is the first European premium manufacturer to use and develop FIR technology for increased customer benefits.
BMW has further developed FIR technology for use in automobiles, extending it to include several other useful functions. The camera used has a significantly larger angle of exposure than that of other systems (between 12 and 18 degrees. In addition, the image section shown on the monitor follows the course of the road and steering angle (panning). Furthermore, a digital zoom can be activated for higher road speeds, showing objects which are further away in enlarged form on the screen. Finally, the iDrive menu can be used to adapt brightness, contrast and screen display according to the individual preferences of the driver. BMW Night Vision is activated/deactivated by means of a switch next to the light switch.
Scientific research also gives a clear message.
In the individual areas of use and technology the two systems NIR and FIR can be distinguished even further. This system comparison goes back in essence to a study by the Transportation Research Institute of the University of Michigan (UMTRI), published in December 2004. UMTRI is one of the leading research institutions in the field of transport and road traffic, and its partners include leading automobile manufacturers and numerous well-known names from the supply industry. UMTRI conducted a scientific comparison of FIR and NIR night vision systems, focusing on the detection of human beings using this system.
· FIR has fewer components.
Due to the fact that there is no internal light source as with the NIR system, FIR systems have fewer components.
· FIR allows you to see “further”:
FIR systems have a range of some 300 m, the average with NIR is 150 m. Thus the distances at which people were detected in the test were significantly larger with FIR. On average, human beings were detected at a distance of 165 m with FIR and at 59 m with NIR in the UMTRI study.
· FIR isn’t “dazzled”:
NIR systems are sensitive to the headlamps of oncoming traffic, traffic lights, street lamps and powerfully reflecting surfaces such as traffic signs. Since NIR systems use light waves as the basis for their image information, especially light-intensive objects appear brightly on the screen, or else they flash or appear as a diffuse shining. This also applies to the light source of the NIR system when detected by another NIR system. NIR systems are thus susceptible to dazzling. By contrast, FIR systems only show objects which radiate heat – the warmer the object, the more intensive the light. Generally speaking,
people and animals are shown as strikingly different from the rest of the traffic situation.
· FIR: reduction to the essentials.
NIR systems provide a complete depiction of the given road situation. However, this delays the detection of a person within the image as a whole. For other purposes NIR may be better suited than FIR, but not for the use in vehicles when identifying people.
Due to the symbolic depiction used by FIR systems (comparable to a photographic negative), information provided by NIR systems is initially processed more quickly by users, since FIR information is felt to be unnatural and difficult to understand. After a period of familiarisation, this is reversed and the information processing speed in detecting people and animals is faster with FIR systems.
Night vision is not a replacement for watching the road!
Night vision systems relieve the driver by providing information. They in no way replace concentration on the road. Similarly, such systems are in no way comprehensive nor do they make it superfluous to be aware of risks and dangers on the road. Weather conditions also influence the quality of image display – both with FIR and NIR. Rain drops and fog filter infrared
light, for example, and this leads to a deterioration of image quality.
When using night vision systems, one should always be aware of a clearly defined purpose. UMTRI argues as follows: “In view of traffic conditions and night accidents, night vision systems should particularly increase the recognisability of people, cyclists and animals.”
