Image-based lighting (IBL) is the process of illuminating scenes and objects (real or synthetic) using images of light from the real world. This is in contrast to using only direct light sources such as point lights or spotlights, which are more localized. A typical use of IBL is taking high-dynamic photos of a chrome ball placed in the original environment of a live-action shoot, then using the photos as an IBL map to simulate the lighting conditions of the shoot. In Action, you can use the IBL node in Reflection mode or Ambient mode (which more closely simulates a global illumination effect).
Light Probe Images courtesy of Paul Debevec, www.debevec.org
In Action, you can use IBL maps to:
- Colour blend images onto the backplate (the IBL map must be a shot of the environment that the backplate was taken from). This technique is useful for green screen work.
- Light 3D geometry or text objects from every direction using the colours in the environment.
You can use IBL maps to make surfaces perfectly reflective or perfectly diffuse. You can also make an IBL map act as a virtual spherical background plate.
Action supports angular, cubic, and cylindrical IBL mapping types. You can use the Map Convert tool to convert images to one of these types.