A PCA Decomposition for Real‐time BRDF Editing and Relighting with Global Illumination

Figure 1: We proposed a new method to render screen-space glossy to glossy reflections in realtime. Three scenes are all with glossy materials and rendered at 1280 × 720 resolution. The FPS of these three snapshots are 65.1, 64.1 and 61.7 respectively. AbstractGlossy to glossy reflections are lights bounced between glossy surfaces. Such directional light transports are important for humans to perceive glossy materials, but difficult to simulate. This paper proposes a new method for rendering screen-space glossy to glossy reflections in realtime. We use spherical von Mises-Fisher (vMF) distributions to model glossy BRDFs at surfaces, and employ screen space directional occlusion (SSDO) rendering framework to trace indirect light transports bounced in the screen space. As our main contributions, we derive a new parameterization of vMF distribution so as to convert the non-linear fit of multiple vMF distributions into a linear sum in the new space. Then, we present a new linear filtering technique to build MIP-maps on glossy BRDFs, which allows us to create filtered radiance transfer functions at runtime, and efficiently estimate indirect glossy to glossy reflections. We demonstrate our method in a realtime application for rendering scenes with dynamic glossy objects. Compared with screen space directional occlusion, our approach only requires one extra texture and has a negligible overhead, 3% ∼ 6% loss at frame rate, but enables glossy to glossy reflections.

Section: Related Workmentioning

confidence: 99%

Realtime Rendering Glossy to Glossy Reflections in Screen Space

Wang

Bao

2015

“…We use the real‐valued SH basis functions,

B = y

where

\begin{matrix} left y_{l}^{m} (ω) = ({, \begin{matrix} K_{l}^{0} P_{l}^{0} (prefixcos ω_{θ}), & m = 0 \\ \sqrt{2} K_{l}^{m} cos (m ω_{φ}) P_{l}^{m} (prefixcos ω_{θ}), & m > 0 \\ \sqrt{2} K_{l}^{| m |} sin (| m | ω_{φ}) P_{l}^{| m |} (prefixcos ω_{θ}), & m < 0 \end{matrix}) and \\ left boldy = ([] y_{0}^{0} (ω), y_{1}^{- 1} (ω), y_{1}^{0} (ω), y_{1}^{1} (ω), y_{2}^{- 2} (ω) ...) \end{matrix}

and m indexes the

(2 l + 1)

band‐ l basis functions,

K_{l}^{m}

is a normalization term, and

P_{l}^{m}

are associated Legendre polynomials. Note, however, that any basis with a double‐ or triple‐product formulation can be employed, including data‐driven bases [NKLN10]. By multiplying

boldB

with an arbitrary f , we can also project visibility‐masked functions onto a basis which is different, and generally more accurate, than performing a product with visibility in the basis space.…”

Section: Applicationsmentioning

confidence: 99%

“…and m indexes the (2l + 1) band-l basis functions, K m l is a normalization term, and P m l are associated Legendre polynomials. Note, however, that any basis with a double-or triple-product formulation can be employed, including data-driven bases [NKLN10]. By multiplying B with an arbitrary f , we can also project visibility-masked functions onto a basis which is different, and generally more accurate, than performing a product with visibility in the basis space.…”

Section: Aomentioning

confidence: 99%

Visibility Silhouettes for Semi‐Analytic Spherical Integration

Nowrouzezahrai

Baran

Mitchell

et al. 2013

“…PRT techniques also have been extended to allow interactive editing of glossy BRDFs with global illumination for a fixed view direction [BAOR06, BAEDR08, NKLN10] or with a dynamic camera [SZC*07].…”

Section: Previous Workmentioning

confidence: 99%

Pre‐computed Gathering of Multi‐Bounce Glossy Reflections

Laurijssen

Wang

Lagae

et al. 2011

Recent work in interactive global illumination addresses diffuse and moderately glossy indirect lighting effects, but high-frequency effects such as multi-bounce reflections on highly glossy surfaces are often ignored. Accurately simulating such effects is important to convey the realistic appearance of materials such as chrome and shiny metal. In this paper, we present an efficient method for visualizing multi-bounce glossy reflections at interactive rates under environment lighting. Our main contribution is a pre-computation-based method which efficiently gathers subsequent highly glossy reflection passes modelled with a non-linear transfer function representation based on the von Mises-Fisher distribution. We show that our gathering method is superior to scattered sampling.To exploit the sparsity of the pre-computed data, we apply perfect spatial hashing. As a result, we are able to visualize multi-bounce glossy reflections at interactive rates at a low pre-computation cost.