A method, system, and computer program product for performing a lighting simulation are disclosed. The method includes the steps of receiving a three-dimensional (3D) model, receiving a set of probes, where each probe specifies a location within the 3D model and an orientation of the probe, and performing, via a processor, a lighting simulation based on the 3D model, the set of probes, and one or more light path expressions. The light path expressions are regular expressions that represent a series of events, each event representing an interaction of a ray at a location in the 3D model.