Ray tracing visualization toolkit

Abstract

Figure 1: Ray Tracing Visualization Toolkit. An extensible GUI, together with a ray state recording library and a collection of visualization components, integrate existing client renderers via a flexible plug-in architecture to support visual analysis of ray-based rendering algorithms. Here, rtVTK is used to visually debug an ill-behaved path tracer. The previously undiscovered bug is not obvious in either a low-quality image with relatively few samples per pixel (top left) or a high-quality image with many more samples per pixel (bottom left). However, when viewing the ray state directly with rtVTK (middle, right), the problem is immediately obvious: some shadow rays originating from diffuse surfaces (circled) are not directed toward any light source in the scene. Once identified, the correction was trivial; however, in its previous state, the renderer was incorrect, and likely would have remained so without the ability to visualize the ray tracing process itself. AbstractThe Ray Tracing Visualization Toolkit (rtVTK) is a collection of programming and visualization tools supporting visual analysis of ray-based rendering algorithms. rtVTK leverages layered visualization within the spatial domain of computation, enabling investigators to explore the computational elements of any ray-based renderer. Renderers utilize a library for recording and processing ray state, and a configurable pipeline of loosely coupled components allows run-time control of the resulting visualization. rtVTK enhances tasks in development, education, and analysis by enabling users to interact with a visual representation of ray tracing computations.

Light Shapes

“…Contrarily, we convert measurement results of complex natural light into three perceptually meaningful parameters that are intuitive also to nonexpert users. Unlike light rays or path visualizations (Gribble et al 2012;Hullin et al 2008;Nowrouzezahrai et al 2011;Schmidt et al 2013;Simons et al 2016;Velten et al 2013), we show preprocessed information that allows users "to see the forest through the trees," i.e. to understand the structure of the light field and its properties' variations in one glance.…”

“…One of the most straightforward methods of light transport visualization is showing it as rays or in the form of ray trees, light paths, or light beams (Gribble et al 2012;Nowrouzezahrai et al 2011;Simons et al 2016). In the field of optics, relevant studies have been done on capturing and visualizing physical light as traces of light through fluorescent liquids or frame-wise propagation of light (Hullin et al 2008;Velten et al 2013).…”

Applying Visual Analytics to Physically Based Rendering

“…Visualization of light rays as geometric primitives helps to understand light propagation [Rus99]. The importance of filtering rays according to attributes or type was shown in [LP14] and made possible by recording the ray state [GFE*12]. On a higher level of abstraction, spherical plots and particle flow tools allow selective inspection of light transport [RKRD12].…”

A Visualization Tool Used to Develop New Photon Mapping Techniques

“…Gribble et al . [GFE*12] create rtVTK as a visualization support system for ray‐based renderers. Like us, they expound the view that realizing a visualization of the ray tracer will lead to a deeper understanding of the process, further leading to new insights.…”