Practical product importance sampling for direct illumination
Författare
Redaktör
- Roberto Scopigno
- Eduard Gröller
Summary, in English
We present a practical algorithm for sampling the product of environment map lighting and surface reflectance.
Our method builds on wavelet-based importance sampling, but has a number of important advantages over previous methods. Most importantly, we avoid using precomputed reflectance functions by sampling the BRDF on-the-fly. Hence, all types of materials can be handled, including anisotropic and spatially varying BRDFs, as well
as procedural shaders. This also opens up for using very high resolution, uncompressed, environment maps. Our
results show that this gives a significant reduction of variance compared to using lower resolution approximations. In addition, we study the wavelet product, and present a faster algorithm geared for sampling purposes.
For our application, the computations are reduced to a simple quadtree-based multiplication. We build the BRDF
approximation and evaluate the product in a single tree traversal, which makes the algorithm both faster and more
flexible than previous methods.
Our method builds on wavelet-based importance sampling, but has a number of important advantages over previous methods. Most importantly, we avoid using precomputed reflectance functions by sampling the BRDF on-the-fly. Hence, all types of materials can be handled, including anisotropic and spatially varying BRDFs, as well
as procedural shaders. This also opens up for using very high resolution, uncompressed, environment maps. Our
results show that this gives a significant reduction of variance compared to using lower resolution approximations. In addition, we study the wavelet product, and present a faster algorithm geared for sampling purposes.
For our application, the computations are reduced to a simple quadtree-based multiplication. We build the BRDF
approximation and evaluate the product in a single tree traversal, which makes the algorithm both faster and more
flexible than previous methods.
Avdelning/ar
Publiceringsår
2008
Språk
Engelska
Sidor
681-690
Publikation/Tidskrift/Serie
Computer Graphics Forum
Volym
27
Issue
2
Länkar
Dokumenttyp
Konferensbidrag
Förlag
Wiley-Blackwell
Ämne
- Computer Science
Nyckelord
- Ray tracing
- Photo-realistic rendering
- Computer graphics
- Importance sampling
Conference name
Eurographics 2008
Conference date
2008-04-14
Conference place
Crete, Greece
Status
Published
Forskningsgrupp
- Computer Graphics
ISBN/ISSN/Övrigt
- ISSN: 0167-7055
- ISSN: 1467-8659