Precomputed Radiance Transfer for X3D based Mixed Reality Applications

Tobias Alexander Franke and Yvonne Jung Proceedings of the 13th international conference on 3D web technology

Teaser Based on an HDR environment map in latitude-longitude format the dragon is rendered via PRT within an X3D browser.


We present a lightweight framework composed of two extensions to introduce precomputed radiance transfer (PRT) to X3D. Depending on the basis function, PRT is used to simulate shading, complex light transfer and effects like subsurface scattering and caustics in real time by projecting incident light and transfer functions into frequency space, which allows the solution of the integration of the rendering equation through a simple dot product. Light transfer from incident to transferred radiance thus becomes a matter of solving dot products of coefficient vectors, which can be easily evaluated on the GPU. In this paper, we identify the minimal set of components needed for an X3D application to use spherical harmonic based PRT, and discuss how further enhancements to PRT can be implemented, like new basis functions and other features.


Supplemental video


 author = {Franke, Tobias and Jung, Yvonne},
 title = {Precomputed radiance transfer for X3D based mixed reality applications},
 booktitle = {Proceedings of the 13th international symposium on 3D web technology},
 series = {Web3D '08},
 year = {2008},
 isbn = {978-1-60558-213-9},
 location = {Los Angeles, California},
 pages = {7--10},
 numpages = {4},
 url = {},
 doi = {10.1145/1394209.1394213},
 acmid = {1394213},
 publisher = {ACM},
 address = {New York, NY, USA},
 keywords = {X3D, image based lighting, mixed reality, precomputed radiance transfer, real time, shader},