Enhancing interactive particle visualization with advanced shading models

Abstract

Figure 1: Comparing shading models. When shading a surface, purely local models do not consider contributions from other surfaces in the environment (left). These models are often augmented with shadows to enhance cues about shape and relative position (middleleft). However, the constant ambient term used to approximate indirect illumination often obscures details in shadowed regions, providing ambiguous or conflicting information. More accurate shading models, for example, ambient occlusion (middle-right) and physically based diffuse interreflection (right), provide better perceptual cues in these regions. AbstractParticle-based simulation methods are used to model a wide range of complex phenomena and to solve time-dependent problems of various scales. Effective visualization of the resulting state should communicate subtle changes in the three-dimensional structure, spatial organization, and qualitative trends within a simulation as it evolves. We take steps toward understanding and using advanced shading models in the context of interactive particle visualization. Specifically, the impact of ambient occlusion and physically based diffuse interreflection is investigated using a formal user study. We find that these shading models provide additional visual cues that enable viewers to better understand subtle features within particle datasets. We also describe a visualization process that enables interactive navigation and exploration of large particle datasets, rendered with illumination effects from advanced shading models. Informal feedback from application scientists indicates that the results of this process enhance the data analysis tasks necessary for understanding complex particle datasets.

Autonomous Particles for Interactive Flow Visualization

“…Gribble et al . [GP06] used a combination of ambient occlusion and diffuse inter‐reflections to create more realistic particle visualizations, which was confirmed in a user study. However, this technique relies on an expensive pre‐computation step.…”

“…The visualization of complex molecule structures also benefit from additional ambient occlusion as demonstrated by Tarini et al [TCM06]. Gribble et al [GP06] used a combination of ambient occlusion and diffuse inter-reflections to create more realistic particle visualizations, which was confirmed in a user study. However, this technique relies on an expensive pre-computation step.…”

LineAO—Improved Three-Dimensional Line Rendering

“…Besides the medical use case, chemical and bio-chemical visualization also profits from more realistic rendering and, e.g., [31] and [32] added ambient occlusion for a better structural perception of very complex molecule structures. Gribble et al applied ambient occlusion to particle rendering and investigated its effect in a formal user study [33].…”

Visualization of Multi‐Variate Scientific Data

“…a vortex) may not cast a shadow in reality, a shadow can very well show spatial relationships between features in the data. Especially for glyphs and disconnected features, lighting is a powerful way to provide better perceptual cues [GP06]. [FS92] introduced cut-away views and ghosting to 3D visualization.…”