Visualizing Temporal Behavior in Multifield Particle Simulations.

Particle-based simulations generate time-varying multifield volumetric datasets. Visualizations of such volumes traditionally focus on the physical space, displaying particles as glyphs or with volume rendering techniques. In this paper we deal specifically with the issue of helping users to observe and interpret the multidimensional feature space and its temporal behavior, as a complement to existing spatial views. Our approach combines multiple visualizations to assist analysis of time-varying data generated by particle simulations. Coordinated views of both feature and physical spaces allow the observation of particle behavior over specific time periods or the whole temporal domain, rather than describing a single simulation time step. Temporal behavior in the physical space is depicted as pathlines, whereas the temporal behavior of the underlying multidimensional feature space is depicted in a so-called streamfeature visualization. Streamfeatures are pathlines describing changes in feature space along time, obtained by projecting the feature vectors. Direct interaction with these line representations is difficult. Thus, two supporting views are supplied for user interaction, which show 2D projections of both the pathlines (pathline projection view) and the streamfeatures (streamfeature projection view), obtained by projecting geometric features extracted from the lines. By linking all visualizations, users may interact with these views to identify and select representative clusters of lines that reflect similar behavior of particle features. We use data from two particle simulations to illustrate the framework and its potential to support analysis of global temporal behavior and relationships between multiple variables.