Explanation
Ray tracing is a rendering technique that simulates the physical behavior of light by tracing rays from the camera through each pixel and calculating how they bounce, refract, and interact with surfaces. It produces photorealistic lighting, reflections, shadows, and refractions, but is extremely computationally demanding -- especially in VR where two images must be rendered at 90 Hz.
Real-world example
The perfectly accurate reflections in puddles and on car paint in the latest-generation video games.
Practical applications
- Realistic lighting: light that behaves as it does in the real world
- Accurate reflections: mirrors, glossy surfaces, and water with faithful reflections
- Soft shadows: natural penumbra and ambient occlusion
- Refractions: glass, diamonds, and liquids with correct optical distortions
Ray tracing in VR
The challenge of VR ray tracing
- Extremely GPU-intensive technique
- VR requires 2 images at 90 Hz -- an extreme constraint
- Compromises are necessary: partial or hybrid ray tracing
Example: Reserved for high-end PCVR configurations
Alternatives for standalone VR
- Pre-computed lighting (baked lighting)
- Less expensive hybrid techniques
- No real-time ray tracing on Quest-class hardware
Example: Light probes combined with simplified shadows
VR scenario
A PCVR automotive configurator uses ray tracing to showcase car finishes. The customer sees their future vehicle with perfect reflections on the bodywork, realistic headlight glare, and soft shadows inside the cabin. The visual fidelity convinces and closes the sale.
Why it matters in professional VR
- Ray tracing is the holy grail of graphical realism
- In VR, its use remains limited to high-end PCVR applications
- Hardware evolution will gradually make VR ray tracing more accessible