Real-time triple product relighting using spherical local-frame parameterization

Abstract

This paper addresses the problem of real-time rendering for objects with complex materials under varying allfrequency illumination and changing view. Our approach extends the triple product algorithm by using local-frame parameterization, spherical wavelets, per-pixel shading and visibility textures. Storing BRDFs with local-frame parameterization allows us to handle complex BRDFs and incorporate bump mapping more easily. In addition, it greatly reduces the data size compared to storing BRDFs with respect to the global frame. The use of spherical wavelets avoids uneven sampling and energy normalization of cubical parameterization. Finally, we use per-pixel shading and visibility textures to remove the need for fine tessellations of meshes and shift most computation from vertex shaders to more powerful pixel shaders. The resulting system can render scenes with realistic shadow effects, complex BRDFs, bump mapping and spatially-varying BRDFs under varying complex illumination and changing view at real-time frame rates on modern graphics hardware.

Soho

“…In the experiments the SOHO wavelet basis was compared to six previously proposed spherical Haar wavelet bases: the Bio-Haar basis developed by Schröder and Sweldens [1995], the two nearly orthogonal bases proposed by Nielson et al [1997], the pseudo Haar wavelets used by Ma et al [2006], and the two nearly orthogonal bases developed by Bonneau [1999]. All bases have been employed to represent three signals: a unimodal function with only low-frequency content, a piecewise constant function with only high-frequency features, and an image-like signal with content in the full frequency spectrum.…”

“…However, none of these works provided detailed experimental results comparing their newly developed bases to incumbent spherical Haar wavelet bases. Ma et al [2006] used a Haar-like pseudo wavelet basis over the sphere for PRT. The basis is identical to that proposed by Bonneau [1999], but the authors assumed the subdivision of a • 4:3 partition yields child domains of equal area.…”

Eigentransport for efficient and accurate all-frequency relighting

“…Ma et al use a spherical wavelet basis to reconstruct the tripleproduct shading integral for arbitrary BRDFs defined using a local parameterization [Ma et al 2006]. As with Haar wavelets defined over cubemaps [Ng et al 2003], a simple rotation algorithm for this basis does not exist.…”

“…Some work has been recently proposed to approximate SH rotation matrices for higher-order expansions [Křivánek et al 2006], however this technique requires almost the same amount of calculation and storage as the full rotation formulation. Ma et al did not propose a rotation scheme for their spherical Haar basis [Ma et al 2006]. …”

Uniformly sampling multi-resolution analysis for image-based relighting

“…In [26], a more practical spherical Haar wavelet basis that is both orthogonal and symmetric was proposed. There are also some previous works [27,28] related to icosahedron for rendering images. However, none of these works demonstrated the advantages of using the uniformly sampling property of an icosahedron.…”