Arvid Schneider Explains the Benefits of Light Path Expressions in Arnold for Creating Custom AOVs

ILM Lighting TD Arvid Schneider covers using Light Path Expressions (LPE) With Arnold in Maya. Light Path Expressions are to output light into specific AOVs or Arbitrary Output Variables. The concept can be a little confusing when it’s explained, so Arvid shows some specific examples of where and when an LPE will be needed.

LPE’s define the light transport as it moves through the scene. Think of tracing a line starting from a source of light, bouncing between objects and finally ending up at the camera.

LPE’s offer a much more flexible workflow. They can easily extract specified light paths using a regular expression language, rather than writing to specific AOVs from shaders. So basically you don’t have to modify shaders to output a custom AOV that uses the LPE.