Multiple Vertex Next Event Estimation for Lighting in dense, forward‐scattering Media. (23rd May 2017)

• Record Type: Journal Article
• Authors: Weber, Pascal; Hanika, Johannes; Dachsbacher, Carsten
• Is Part Of: Computer graphics forum. Volume 36:Number 2(2017)
• Page Start: 21
• Page End: 30
• Publication Date: 2017-05-23
• Subjects: Categories and Subject Descriptors (according to ACM CCS) -- I.3.7 [Computer Graphics]: Three Dimensional Graphics and Realism—Raytracing; Computer graphics -- Periodicals; 006.605
• DOI: 10.1111/cgf.13103
• Languages: English
• ISSNs: 0167-7055

Abstract

Abstract: We present a new technique called Multiple Vertex Next Event Estimation, which outperforms current direct lighting techniques in forward scattering, optically dense media with the Henyey‐Greenstein phase function. Instead of a one‐segment connection from a vertex within the medium to the light source, an entire sub path of arbitrary length can be created and we show experimentally that 4–10 segments work best in practice. This is done by perturbing a seed path within the Monte Carlo context. Our technique was integrated in a Monte Carlo renderer, combining random walk path tracing with multiple vertex next event estimation via multiple importance sampling for an unbiased result. We evaluate this new technique against standard next event estimation and show that it significantly reduces noise and increases performance of multiple scattering renderings in highly anisotropic, optically dense media. Additionally, we discuss multiple light sources and performance implications of memory‐heavy heterogeneous media.