Seeing Clearly In Sun Glare

August 18, 2022

What is Sun Glare?
Sun Glare occurs when the upper edge of the sun sinks under or above the horizon. As our eyes are highly sensitive to light, the bright light emitted from the sun’s positioning obscures our vision and impacts our ability see objects, like pedestrians, and judge relative distances.

Sun glare causes over-exposure in the image and significantly impacts perception algorithms. Sun glare can be indirect, when sunlight is reflected off the wet road or other surfaces, or direct, when sun glare hits the driver’s eyes. Several studies in Canada and the US found a direct correlation between sun glare and car crashes, as well as between sun glare and increased risk of life-threatening crashes.


Current Challenges
A significant reason why Advanced Driver Assistance Systems (ADAS) are incapable of providing full autonomy is that they rely on a combination of visible (VIS) cameras, radars and LiDARs which exhibit limitations in adverse weather and lighting conditions. VIS cameras are prone to perception issues that we, as humans, experience. This means that in conditions where there is direct sunlight or lowlight (i.e shadows, night time) it is highly probable that VIS cameras will fail to “see”.

LiDARs operate in the near-infrared spectrum which is susceptible to glare from the sun. In addition, the LiDAR produces insufficient resolution. As such, ADAS systems do not have accurate and actionable information about the immediate environment when they are needed most.


Overcoming Sun Glare with Environmentally Immune Sensing System
The TriEye system operates in the solar blind region within the Short-Wave Infrared (SWIR) spectrum , at around 1400nm, therefore it is unaffected by ambient noise from the sun, providing a clear image regardless of glare. This unique property means that other common disruptive effects resulting from the sun, like shade patterns, are eliminated, leaving a complete and detailed image of the shaded object that can be analysed.

These characteristics, when operated properly, result in a higher Signal to Noise Ratio, enhanced sight and an overall improvement of image quality under common low-visibility scenarios such as strong sun glare. This allows SWIR cameras to offer superior vision, providing critical information and increasing the detection range significantly.




As shown in figure 1, SWIR sensors operate around 1,400 nm where solar irradiance is significantly reduced, on the other hand, other sensors operating in the near infrared (700 to 1,000 nm) or visible (380 to 700 nm) spectrums are significantly affected by ambient noise from the sun.


The Ultimate Perception System
Introducing the SEDAR (Spectrum Enhanced Detection And Ranging), the ultimate perception system for ADAS and AV. TriEye’s SEDAR is based on two world’s first innovations: TriEye’s Raven, an HD CMOS-based SWIR photosensor, and the UltraBlaze, TriEye’s ultra-high power, and eye-safe SWIR illumination source.

Harnessing the SWIR spectrum’s physical advantages, the SEDAR simultaneously provides both SWIR HD image data & a detailed depth-map in all visibility conditions. With these two data flows, the SEDAR provides the benefits of a camera, night vision camera and a LiDAR in one system. Leveraging TriEye’s CMOS-based SWIR sensor and proprietary illumination module, the SEDAR enables high-resolution imaging and ranging that is cost-effective, scalable, and has a small form factor.

The SEDAR provides accurate depth information in the form of a high resolution depth map, with depth calculated per pixel. This is done using a pulse-based illumination methodology, which can only be implemented in the SWIR spectrum in order to be completely eye safe. As the SEDAR’s illumination works in strong but short pulses, the sun does not interfere with the sensor’s ability to “see” the road ahead. This unique illumination methodology along with the advanced properties of the SWIR spectrum make the SEDAR environmentally immune. Thus, unlike other sensors, TriEye’s SEDAR is able to provide superior sight, functionality and operability even when faced with blinding rays from the sun.





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