Title
All-frequency precomputed radiance transfer for glossy objects
Abstract
We introduce a method based on precomputed radiance transfer (PRT) that allows interactive rendering of glossy surfaces and includes shadowing effects from dynamic, "all-frequency" lighting. Specifically, source lighting is represented by a cube map at resolution nL = 6 × 32 × 32. We present a novel PRT formulation which factors glossy BRDFs into purely view-dependent and light-dependent parts, achieving reasonable accuracy with only m=10 dimensional factors. We then tabulate an m × nL transfer matrix at each surface vertex as a preprocess, representing the object's response to this lighting. Because this surface signal is so high-dimensional, reducing m is crucial for making practical both the preprocessing and run-time. To compress the transfer matrices, we divide the cube map into 24 lighting segments and apply the Haar wavelet basis in each segment to provide sensible quantization. We also apply clustered principal component analysis (CPCA) to each PRT segment to approximate it as a linear combination of a few (n=16) representative transfer matrices within a small set of clusters over the surface. This exploits spatial coherence to compress very effectively. Most important, it maintains fast rendering rates with 2-3 orders of magnitude more lighting coefficients than previous methods, which increases accuracy and avoids temporal artifacts in high-frequency lighting environments. We demonstrate interactive performance (1-5Hz) on models having up to 50,000 vertices.
Year
DOI
Venue
2004
10.2312/EGWR/EGSR04/337-344
Rendering Techniques
Keywords
Field
DocType
cube map,glossy object,source lighting,transfer matrix,lighting coefficient,nl transfer matrix,prt segment,glossy surface,precomputed radiance transfer,high-frequency lighting environment,representative transfer matrix,principal component analysis,high frequency
Linear combination,Computer vision,Computer graphics (images),Cube mapping,Computer science,Matrix (mathematics),Artificial intelligence,Precomputed Radiance Transfer,Haar wavelet,Quantization (signal processing),Rendering (computer graphics),Cube
Conference
ISBN
Citations 
PageRank 
3-905673-12-6
70
2.17
References 
Authors
16
4
Name
Order
Citations
PageRank
Xinguo Liu140425.92
Peter-Pike Sloan279645.22
Heung-Yeung Shum310824739.88
John Snyder42579172.17