What is the difference between baked GI and real-time GI, and when would you use each?

• A. Baked GI precomputes static lighting for static geometry to save runtime cost.
• B. Real-time GI precomputes lighting based on time of day.
• C. Baked GI updates lighting every frame.
• D. Real-time GI uses pre-baked lightmaps.

Answer: (A)

Global illumination can be handled in two ways: baked and real-time. Baked GI precomputes how light bounces through a scene and stores that data for static geometry as lightmaps. Because the lighting is baked, the runtime can render frames without recalculating those bounces, which saves a lot of performance. This approach is ideal when the geometry and lighting don’t change, like static environments or scenes where lights stay put for long periods.

Real-time GI, by contrast, calculates lighting during gameplay, allowing objects and lights to move and scenes to change dynamically. It provides accurate lighting for dynamic situations but costs more GPU time, so it’s used when you need motion or changing illumination.

So baked GI is best for static scenes to maximize performance, while real-time GI is chosen for dynamic scenes where lighting needs to adapt.