Real-time polygonal-light shading with linearly transformed cosines

Many‐light rendering is becoming more common and important as rendering goes into the next level of complexity. However, to calculate the illumination under many lights, state of the art algorithms are still far from efficient, due to the separate consideration of light sampling and BRDF sampling. To deal with the inefficiency of many‐light rendering, we present a novel light sampling method named BRDF‐oriented light sampling, which selects lights based on importance values estimated using the BRDF's contributions. Our BRDF‐oriented light sampling method works naturally with MIS, and allows us to dynamically determine the number of samples allocated for different sampling techniques. With our method, we can achieve a significantly faster convergence to the ground truth results, both perceptually and numerically, as compared to previous many‐light rendering algorithms.

Section: Related Workmentioning

confidence: 99%

“…We use Spherical Pivot Transformed Distributions (SPTDs)[DHB17] to quickly compute an approximation of the integral. Other solutions, such as the Linear Transformed Consines (LTCs)[HDHN16] could give more accurate results, but with much more overhead.Light cluster sampling. For each shading point, once we have determined the light cut, i.e.…”

mentioning

confidence: 99%

Adaptive BRDF‐Oriented Multiple Importance Sampling of Many Lights

Liu

Yan

2019

“…An analytic convolution would have similar results as the virtual merge approach, but without the additional random decision. An approximate solution to this problem was given by Heitz et al [HDHN16] using cosine lobes.…”

Section: Johannes Jendersie Thorsten Grosch / Microfacet Model Regulmentioning

confidence: 99%

Microfacet Model Regularization for Robust Light Transport

Jendersie

Grosch

2019

Today, Monte Carlo light transport algorithms are used in many applications to render realistic images. Depending on the complexity of the used methods, several light effects can or cannot be found by the sampling process. Especially, specular and smooth glossy surfaces often lead to high noise and missing light effects. Path space regularization provides a solution, improving any sampling algorithm, by modifying the material evaluation code. Previously, Kaplanyan and Dachsbacher [KD13] introduced the concept for pure specular interactions. We extend this idea to the commonly used microfacet models by manipulating the roughness parameter prior to the evaluation. We also show that this kind of regularization requires a change in the MIS weight computation and provide the solution. Finally, we propose two heuristics to adaptively reduce the introduced bias. Using our method, many complex light effects are reproduced and the fidelity of smooth objects is increased. Additionally, if a path was sampleable before, the variance is partially reduced.

“…The area light is actually what we refer to as an LPAL. While real‐time rendering for scenes with area lights have been intensely studied [Arv95; Dro14; HDHN16; LDSM17], we employed the approach proposed by Heitz et al [HDHN16] because of its fast calculation and applicability to glossy surfaces. Following their method, we calculate the integration using the following formula:…”

Section: Indirect Illumination With Layered Polygonal Area Lightsmentioning

confidence: 99%

Real‐time Indirect Illumination of Emissive Inhomogeneous Volumes using Layered Polygonal Area Lights

Kuge

Yatagawa

Morishima

2019

Indirect illumination involving with visually rich participating media such as turbulent smoke and loud explosions contributes significantly to the appearances of other objects in a rendering scene. However, previous real‐time techniques have focused only on the appearances of the media directly visible from the viewer. Specifically, appearances that can be indirectly seen over reflective surfaces have not attracted much attention. In this paper, we present a real‐time rendering technique for such indirect views that involves the participating media. To achieve real‐time performance for computing indirect views, we leverage layered polygonal area lights (LPALs) that can be obtained by slicing the media into multiple flat layers. Using this representation, radiance entering each surface point from each slice of the volume is analytically evaluated to achieve instant calculation. The analytic solution can be derived for standard bidirectional reflectance distribution functions (BRDFs) based on the microfacet theory. Accordingly, our method is sufficiently robust to work on surfaces with arbitrary shapes and roughness values. In addition, we propose a quadrature method for more accurate rendering of scenes with dense volumes, and a transformation of the domain of volumes to simplify the calculation and implementation of the proposed method. By taking advantage of these computation techniques, the proposed method achieves real‐time rendering of indirect illumination for emissive volumes.