Path Tracing

Computer Graphics · Light Transport · 1986 · path-tracing.yaml

Solves the rendering equation by tracing random walks from the camera and averaging their contributions. Unbiased and simple, and the baseline every other transport algorithm is measured against.

• supersedescorrects · extends
• classifiesspecializes · part-of
• substitutes forapproximates · alternative-to
• depends onrequires · validates

Colour is the family; a dashed line is the second member of it.

This node

• specializesis a specific case of The Rendering Equationexpands the recursive integral into random walks
• specializesis a specific case of Monte Carlo Integrationthe sample space is the space of light paths
• extendsadds capability to Whitted Ray Tracingrandomizes every bounce instead of only mirrors

Referenced by

• extendsBidirectional Path Tracing adds capability to thisalso grows a subpath from the light side
• correctsIrradiance Caching fixes a defect in thisdiffuse indirect is smooth, so per-pixel sampling is wasted
• extendsNeural Radiance Cache adds capability to thisterminates paths into a cache learned while rendering
• correctsNext Event Estimation fixes a defect in thisrandom walks almost never hit small light sources
• correctsPath Guiding fixes a defect in thisBSDF sampling ignores where the light actually is
• correctsPhoton Mapping fixes a defect in thiscaustics through glass essentially never converge
• alternative-toRadiosity is a competing approach to thisview-independent solve instead of per-pixel sampling
• correctsRussian Roulette fixes a defect in thiscutting paths at a fixed depth loses energy
• extendsVolumetric Path Tracing adds capability to thispaths can scatter inside a volume, not only at surfaces

References

• The Rendering Equation — Kajiya — 1986 · link
• Background — Path tracing on Wikipedia