Particle tracing in unstructured grids
Particle tracing is a widely used method to analyze and interpret results of flow simulations. In addition, it is a preliminary step for more advanced techniques like line integral convolution. For interactive exploration of large data sets, a very efficient and reliable particle tracing method is needed. For data on unstructured grids and data sizes, as they appear in simulations of wind channel experiments or flight simulations, the traditional approach, based on numerical integration methods of ordinary differential equations does not allow sufficiently accurate path calculation at the speed required for interactive use. In this paper we extend the local exact approach of Nielson and Jung in such a way that it can be used for interactive particle tracing in large data sets of steady flow simulation experiments. This will be achieved by sophisticated preprocessing using additional memory. For further visual enhancement of the streamline we construct an implicitly defined smooth Bézier curve that is used for ray tracing. This allows us to visualize additional scalar values of the simulation as attributes to the trajectory and enables the display of high-quality smooth curves without creating additional geometry for a good impression of the spatial situation.