The Visual Computer

, Volume 26, Issue 3, pp 217–226

Grouped photon mapping

Original Article

DOI: 10.1007/s00371-009-0397-2

Cite this article as:
Chen, LH., Tsai, TC. & Chen, YS. Vis Comput (2010) 26: 217. doi:10.1007/s00371-009-0397-2


This paper proposes a novel architecture called Grouped Photon Mapping, which combines standard photon mapping with the light-beam concept to improve the nearest-neighbor density estimation method. Based on spatial coherence, we cluster all of photons, which are deposited in the photon map, into different beam-like groups. Each group of photons is individually stored in an isolated photon map. By the distribution of the photons in each photon map, we construct a polygonal boundary to represent a beam-like illuminated area. These boundaries offer a more accurate and flexible sampling area to filter neighbor photons around the query point. In addition, by a level of detail technique, we can control the photon-count in each group to obtain a balance between biases and noise. The results of our experiments prove that our method can successfully reduce bias errors and light leakage. Especially, for complicated caustic effects through a gemstone-like object, we can render a smoother result than standard photon mapping.

Photon mappingDensity estimationGlobal illuminationCaustics

Copyright information

© Springer-Verlag 2009

Authors and Affiliations

  1. 1.Department of Computer Science and Information EngineeringNational Chi Nan UniversityNantou Hsien, TaiwanROC