Practical product importance sampling for direct illumination
Author
Editor
- 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.
Department/s
Publishing year
2008
Language
English
Pages
681-690
Publication/Series
Computer Graphics Forum
Volume
27
Issue
2
Links
Document type
Conference paper
Publisher
Wiley-Blackwell
Topic
- Computer Science
Keywords
- Ray tracing
- Photo-realistic rendering
- Computer graphics
- Importance sampling
Conference name
Eurographics 2008
Conference date
2008-04-14
Conference place
Crete, Greece
Status
Published
Research group
- Computer Graphics
ISBN/ISSN/Other
- ISSN: 0167-7055
- ISSN: 1467-8659