Performance Tips

intermediate performance

Radiant GI (Built-in) · Troubleshooting & FAQ

Radiant GI is designed to be efficient, but like any real-time GI solution, settings must be tuned to match your target hardware. This page provides guidelines for optimizing performance.

Recommended Baseline Settings

The following configuration (matching the Atrium demo scene) provides a good balance of quality and performance:

Parameter	Value	Notes
Indirect Intensity	1.5	Adjust per scene
Ray Count	1	Each extra ray is expensive
Max Distance	8	Cover the room, no more
Max Samples	24	Lower = faster; increase jittering to compensate
Thickness	1	0.3–1 range
Binary Search	On	Small overhead for better accuracy
Downsampling	1	Increase to 2 for lower-end GPUs
Raytracer Accuracy	8	Reduce for faster tracing
Smoothing	3	Level 4 is expensive; 3 is usually enough
Temporal Filter	On	Essential for stable results
Reuse Rays	1	Nearly free fallback

Performance Tuning Guide

Fastest Gains (Start Here)

Action	Impact	Trade-off
Increase Downsampling to 2	High	Softer GI, less detail
Reduce Raytracer Accuracy	High	Less precise depth sampling
Reduce Max Samples to 16	Medium	May cause banding; increase Jittering
Reduce Max Distance	Medium	GI won’t reach far surfaces

Quality Improvements (When Budget Allows)

Action	Impact	Cost
Increase Ray Count to 2	Smoother, less noise	~2x GPU cost
Enable One Extra Bounce	Richer indirect light	Low
Increase Smoothing to 4	Cleaner output	Medium
Enable reflection probes fallback	Better off-screen data	Medium

Platform-Specific Tips

Mobile / low-end GPU: Downsampling = 2, Ray Count = 1, Max Samples = 16, Smoothing = 2
Mid-range GPU: Use the baseline settings above
High-end GPU: Ray Count = 2, Max Samples = 32, Smoothing = 4
WebGL: Use Downsampling = 2, reduce Max Distance to cover only the visible area

Profiling

Use Unity’s Frame Debugger (Window → Analysis → Frame Debugger) to inspect Radiant GI’s render passes. Key passes to monitor:

Radiant GI Ray March — main cost, affected by Ray Count and Max Samples
Radiant GI Blur — affected by Smoothing level
Radiant GI Temporal — usually lightweight
Radiant RSM — only present if Reflective Shadow Maps are enabled

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