Selective Inspection and Interactive Visualization of Light Transport in Virtual Scenes

This paper presents novel interactive visualization techniques for inspecting the global light transport in virtual scenes. First, we propose a simple extension to photon mapping to gather required lighting information. We then introduce a set of five light inspection tools which process this data to provide further insights. Corresponding visualizations help the user to comprehend how light travels within a scene, how the lighting affects the appearance of a surface, and how objects cause lighting effects such as caustics. We implemented all tools for direct usage in real production environments. Rendering is based on progressive photon mapping, providing interactivity and immediate visual feedback. We conducted a user study to evaluate all techniques in various application scenarios and hence discuss their individual strengths and weaknesses. Moreover, we present feedback from domain experts.