Bidirectional Path Tracing

Computer Graphics · Light Transport · 1993 · also: BDPT · bidirectional-path-tracing.yaml

Trace a subpath from the camera and another from a light, then connect every pair of vertices. Finds paths that neither direction would find alone, such as a room lit only through a narrow doorway.

• 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

• extendsadds capability to Path Tracingalso grows a subpath from the light side
• requiresdoes not work without Multiple Importance Samplingthe same path is built many ways and must be weighted

Referenced by

• extendsMetropolis Light Transport adds capability to thisexplores near paths that already found light
• alternative-toPhoton Mapping is a competing approach to thiscaches light subpaths instead of connecting to them
• extendsVertex Connection and Merging adds capability to thisadds photon merging as an extra connection strategy

References

• Bi-Directional Path Tracing — Lafortune, Willems — 1993
• Bidirectional Estimators for Light Transport — Veach, Guibas — 1994 · link