Tri-Focal Camera

The tri-focal camera is a forward-facing automotive perception setup typically comprising three lenses with different focal lengths: wide-angle, mid-range, and telephoto. It is designed to resolve the inherent limitation of a single camera, which struggles to balance both a wide field of view and long-range visibility simultaneously. By delegating specific tasks to lenses of varying focal lengths, the system ensures more comprehensive monitoring of the road ahead.

💡 Why Do We Need a Tri-Focal Setup?

A monocular camera relies on a single lens to handle all tasks—much like expecting a person to focus on something right in front of them while clearly spotting an object 100 metres away at the same time. The tri-focal approach divides these duties: the wide-angle lens captures close-up and wider fields of view, ideal for spotting pedestrians or sudden road hazards; the mid-range lens covers standard driving conditions as the primary everyday workhorse; and the telephoto lens handles long-distance detection, buying crucial reaction time for high-speed automated functions such as Autonomous Emergency Braking (AEB) and Adaptive Cruise Control (ACC).

🛠️ What Does a Typical Setup Look Like?

A prime example is BYD's highly anticipated "God's Eye" perception system. Its forward-facing tri-focal setup features two 8-megapixel wide-angle cameras and one 8-megapixel telephoto camera, colloquially dubbed the "Erlang Shen's Eye".

• A unique dual-wide + telephoto configuration: What sets this system apart is that the two wide-angle lenses form a dedicated stereo (binocular) vision setup. Using disparity algorithms, it delivers precise depth perception and generates dense point-cloud data. It can even detect minor road surface imperfections and potholes to support active suspension preview functions. Meanwhile, the telephoto lens identifies distant traffic lights, vehicles, and smaller obstacles, extending the forward perception range up to 350 metres.

• Democratising advanced driver-assist technology: As a pure vision-based setup, it eliminates the need for expensive LiDAR sensors, keeping hardware costs competitive. BYD's "God's Eye C" leverages this tri-focal architecture as the backbone of its advanced driving assist suite, with plans to cascade the tech down to mass-market models priced under RM100,000, such as the Seagull and Dolphin, making premium ADAS accessible to more motorists.

💡 Challenges and Trade-Offs

Naturally, the tri-focal configuration comes with its own set of hurdles. Higher hardware costs, the complexity of precisely calibrating three separate camera sensors, and the intensive computing power required for multi-camera sensor fusion present real engineering challenges. Striking the right balance between sensing accuracy, safety redundancy, and mass-production viability remains key to the widespread adoption of this technology.

It is worth noting that while carmakers like BYD are actively pushing tri-focal systems, Tesla—which previously used a tri-camera setup on its older HW2.0 and HW2.5 hardware—has reverted to a dual-camera layout on its latest HW4.0 architecture. This underscores how autonomous perception strategies continue to evolve across the industry.