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Ambient Light Node

By Kriss Norde

The Ambient Light lights the whole scene evenly, with no direction or position. No shadows, no falloff. Its main use: a fill light that keeps shadowed areas from going completely black in a 3D render.

Overview

Ambient Light adds a constant global illumination to every surface, whatever its orientation or position. Every pixel receives the same amount of light, which avoids completely black areas in deep shadows.

It is the simplest light in Fusion: no position ("no real position or rotation"), no shadows, no falloff. In return, it is fast and perfect as the base of a global lighting setup.

Where to find this node

  • Effects Library: Tools > 3D > Light > Ambient Light
  • Quick add: right-click in the Node Editor → Add Tool > 3D > Light > Ambient Light

Inputs

  • SceneInput (orange) - optional. When connected, the node's transforms apply to the whole scene passing through it.

Setup

Connect it directly to a Merge 3D - the light is never visible on its own in a viewer.

Shape 3D ──┐
Ambient Light ─┼→ Merge 3D ← Camera 3D → Renderer 3D
Directional Light ─┘

Controls tab

Enabled (default: on)
Turns the effect on/off (mirrors the node's red switch).
Color (default: white)
Tint of the light. Blue-gray for a cool mood, orange for a warm mood.
Intensity (default: 0.2 - typical value)
Strength of the light. At 0.2, a pure white surface renders as 20% gray (R=G=B=0.2). Typical values: 0.1-0.3 for a subtle fill, up to 0.5 for more global lighting.

Ambient Light vs other lights

Ambient Light (this node)
Even everywhere, no shadows, no falloff. Fast.
Directional Light
Parallel rays (like the sun). Direction matters, sharp shadows. To simulate the sun or a studio key light.
Point Light
A point source (like a light bulb). 360°, falloff with distance, shadows possible.
Spot Light
A cone of light (like a spotlight). Direction + cone angle, shadows, falloff. The most controllable.

Rule of thumb: combine Ambient (fill) + Directional or Point/Spot (key) and a classic three-point lighting setup starts to take shape.

Use cases

  • Global fill light - Intensity 0.1-0.3 to lift the shadows slightly. A classic in CG film lighting to avoid muddy blacks.
  • Flat lighting for a product packshot - Ambient Intensity 0.5+ gives an even render, useful to show an object without lighting distractions.
  • Simulating indirect diffuse light - in pseudo-GI, the Ambient roughly replaces the bounce lighting you would get with real path tracing.
  • Global colored mood - a tinted Color (blue, pink, green) quickly brings atmosphere to the whole scene (bluish night scene, orange sunset).
  • Preview without complex lighting - a single Ambient Light is enough to see the scene and adjust the geometry. Remove it once the final lighting is built.

Tips

  • Intensity 0.2 = rule of thumb for a believable fill. Stronger crushes the shadows, weaker leaves the dark areas too muddy.
  • Never any shadows - if you see no shadows in your scene, that is normal with an Ambient alone. Add a Directional or Spot to get shadows.
  • Several Ambients with different ranges - by placing different Ambients in separate Merge 3D nodes, you can give different objects different "moods".
  • A color complementary to the key - a classic: if the key light is warm (orange), a cool (blue-gray) Ambient = a natural color contrast, the "night scene" kind.
  • Do not confuse it with the Ambient Light mode of Projector 3D, which is a completely different feature.