Ambient light is soft illumination that permeates a scene. In nature, the source of ambient light is the sky where direct sunlight is scattered in the atmosphere. In interior spaces, ambient light is the cumulative effect of light reflecting and scattering off various surfaces. This diffuse lighting helps to reveal form in the shadows and is an important ingredient in realistic shading.

The ambient light intensity affects the overall brightness of the shadows in a scene.

Experiment with the slider above to see how ambient light intensity affects the scene. Notice how increasing the ambient light brightens the shadows and reduces contrast, while decreasing it darkens the shadows and increases contrast.