Photon Differentials

Lars Schjøth, Jeppe Revall Frisvad, Kenny Erleben, Jon Sporring

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    Abstract

    A number of popular global illumination algorithms use density estimation to approximate indirect illumination. The density estimate is performed on finite points - particles - generated by a stochastic sampling of the scene. In the course of the sampling, particles, representing light, are stochastically emitted from the light sources and reflected around the scene. The sampling induces noise, which in turn is handled by the density estimate during the illumination reconstruction. Unfortunately, this noise reduction imposes a systematic error (bias), which is seen as a blurring of prominent illumination features. This is often not desirable as these may lose clarity or vanish altogether. We present an accurate method for reconstruction of indirect illumination with photon mapping. Instead of reconstructing illumination using classic density estimation on finite points, we use the correlation of light footprints, created by using Ray Differentials during the light pass. This procedure gives a high illumination accuracy, improving the trade-off between bias and variance considerable as compared to traditional particle tracing algorithms. In this way we preserve structures in indirect illumination.
    Original languageEnglish
    Title of host publicationProceedings of GRAPHITE 2007 : 5th International Conference on Computer Graphics and Interactive Techniques in Australasia and Southeast Asia
    PublisherACM
    Publication date2007
    Pages179-186
    ISBN (Print)978-1-59593-912-8
    DOIs
    Publication statusPublished - 2007
    Event5th International Conference on Computer Graphics and Interactive Techniques in Australasia and Southeast Asia - Perth, Australia
    Duration: 1 Dec 20074 Dec 2007
    Conference number: 5
    http://graphite.siggraph.org/

    Conference

    Conference5th International Conference on Computer Graphics and Interactive Techniques in Australasia and Southeast Asia
    Number5
    CountryAustralia
    CityPerth
    Period01/12/200704/12/2007
    Internet address

    Keywords

    • caustics
    • ray tracing
    • photon mapping
    • global illumination
    • ray differentials

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