Embree ray tracing kernels for CPUs and the Xeon Phi architecture

International audienceThis paper explores constrained convex space partition (CCSP) as a new acceleration structure for ray tracing. A CCSP is a graph, representing a space partition made up of empty convex volumes. The scene geometry is located on the boundary of the convex volumes. Therefore, each empty volume is bounded with two kinds of faces: occlusive ones (belonging to the scene geometry), and non-occlusive ones. Given a ray, ray casting is performed by traversing the CCSP one volume at a time, until it hits the scene geometry. In this paper, this idea is applied to architectural scenes. We show that CCSP allows to cast several hundreds of millions of rays per second, even if they are not spatially coherent. Experiments are performed for large furnished buildings made up of hundreds of millions of polygons and containing thousands of light sources

Section: Resultsmentioning

confidence: 73%

Constrained Convex Space Partition for Ray Tracing in Architectural Environments

Maria

Horna

Aveneau

2016

“…We have combined the previously proposed visualization techniques into a custom‐built C++ OpenGL application and adapted the unidirectional path‐tracing EMBREE renderer [WFWB13] for our purposes. For the estimator evaluation, we used data which we pre‐computed with the PBRT renderer [PH10] and dumped to disk, as the technique requires a reference image.…”

Section: Resultsmentioning

confidence: 99%

Applying Visual Analytics to Physically Based Rendering

Simons¹,

Herholz

Petitjean

et al. 2018

Physically based rendering is a well‐understood technique to produce realistic‐looking images. However, different algorithms exist for efficiency reasons, which work well in certain cases but fail or produce rendering artefacts in others. Few tools allow a user to gain insight into the algorithmic processes. In this work, we present such a tool, which combines techniques from information visualization and visual analytics with physically based rendering. It consists of an interactive parallel coordinates plot, with a built‐in sampling‐based data reduction technique to visualize the attributes associated with each light sample. Two‐dimensional (2D) and three‐dimensional (3D) heat maps depict any desired property of the rendering process. An interactively rendered 3D view of the scene displays animated light paths based on the user's selection to gain further insight into the rendering process. The provided interactivity enables the user to guide the rendering process for more efficiency. To show its usefulness, we present several applications based on our tool. This includes differential light transport visualization to optimize light setup in a scene, finding the causes of and resolving rendering artefacts, such as fireflies, as well as a path length contribution histogram to evaluate the efficiency of different Monte Carlo estimators.

“…The authors of LightSlice have made their code publicly available, which also includes an implementation of Lightcuts. In order to do fair comparisons between all three methods, we have ported their implementation of LightSlice (and Lightcuts) into the ray‐tracing system Intel Embree [WFWB13] without modifying the core of the algorithms. Our code is also written to use Embree as its ray‐tracing engine.…”

Section: Resultsmentioning

confidence: 99%

Global Illumination Using Well‐Separated Pair Decomposition

Bus

Mustafa

Biri

2015

International audienceInstant radiosity methods rely on using a large number of virtual point lights (VPLs) to approximate global illumination. Efficiency considerations require grouping the VPLs into a small number of clusters that are treated as individual lights with respect to each point to be shaded. Two examples of clustering algorithms are Light-cuts [WFA * 05] and LightSlice [OP11]. In this work we use the notion of geometric separatedness of point sets as a basis for a data structure for pre-computing and compactly storing a set of candidate VPL clusterings. Our data structure is created prior to rendering, is view-independent and relies only on geometric and radiometric information. For any point to be shaded, we show that a suitable clustering of the VPLs can be efficiently extracted from this data structure. We develop the above framework into an accurate and efficient clustering algorithm based on well-separated pair decompositions which outperforms earlier work in speed and/or quality for diffuse scenes