Lighting & rendering · Intermediate
Global illumination
Light that bounces between surfaces, filling shadows and carrying color
Also called GI, indirect lighting
What is global illumination?
Global illumination is light that has bounced off other surfaces before reaching what you see, plus the methods renderers use to calculate it. It fills shadows with soft light, carries color from a red wall onto a white floor, and makes rooms look naturally lit instead of flat.
Think of it like this
It is like sunlight through one window lighting a whole room: it hits the floor, bounces to the walls and fills the corners.
Where it fits in a 3D project
- Create
- Surface
- Rig
- Animate
- Render
- Export
Render: Lighting the scene and turning it into images or video.
How global illumination works
- 01Direct light travels from a lamp straight to a surface.
- 02Some of that light bounces off, picking up the surface’s color.
- 03The bounced light reaches other surfaces, lighting areas no lamp faces directly.
- 04The renderer adds up direct and indirect light for each point.
Global illumination vs ambient occlusion
| Property | Global illumination | Ambient occlusion |
|---|---|---|
| What it adds | Bounced light and color | Darkening in creases and corners |
| Based on | Light paths in the scene | How close nearby geometry is |
| Cost | Higher | Lower |
| Realism | Full indirect lighting | Contact shadows only |
Ambient occlusion is a cheap stand-in for one part of global illumination; use real global illumination when the light itself must look right.
Where global illumination is used
- Architectural interiors
- Product shots with soft, natural shadows
- Baked lighting in game levels
Beginner tip
If an interior render looks dark and blotchy, the light probably needs more bounces or samples. Raise those before adding extra lamps, which can flatten the mood.
Terms related to global illumination
- Lighting & renderingPath tracingRay tracing that follows light through many bounces for photoreal images
- Lighting & renderingRay tracingRendering by following rays of light for true reflections and shadows
- Texturing & materialsAmbient occlusionThe soft darkening in corners and cracks where less light reaches
- Lighting & renderingLightmapA texture of baked lighting that lets real-time scenes look richly lit
- Lighting & renderingImage-based lightingLighting a 3D scene with a panoramic image of its surroundings
- Lighting & renderingRenderingTurning a 3D scene into finished images or video frames
Global illumination FAQ
Updated October 29, 2026 · Browse all 3D terms