The 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.

The wide availability of commodity graphics processors has made real-time graphics an intrinsic component of the human/computer interface. These graphics cores accelerate the z-buffer algorithm and provide a highly interactive experience at a relatively low cost. However, many applications in entertainment, science, and industry require high quality lighting effects such as accurate shadows, reflection, and refraction. These effects can be difficult to achieve with z-buffer algorithms but are straightforward to implement using ray tracing. Although ray tracing is computationally more complex, the algorithm exhibits excellent scaling and parallelism properties. Nevertheless, ray tracing memory access patterns are difficult to predict and the parallelism speedup promise is therefore hard to achieve.

We present an approach to visualizing particle-based simulation data using interactive ray tracing and describe an algorithmic enhancement that exploits the properties of these data sets to provide highly interactive performance and reduced storage requirements. This algorithm for fast packet-based ray tracing of multilevel grids enables the interactive visualization of large time-varying data sets with millions of particles and incorporates advanced features like soft shadows. We compare the performance of our approach with two recent particle visualization systems: one based on an optimized single ray grid traversal algorithm and the other on programmable graphics hardware. This comparison demonstrates that the new algorithm offers an attractive alternative for interactive particle visualization.

The Material Point Method is used for complex simulation of solid materials represented using many individual particles. Visualizing such data using existing polygonal or volumetric methods does not accurately encapsulate both the particle and macroscopic properties of the data. In this case study we present various methods used to visualize the particle data as spheres and explain and evaluate two methods of augmenting the visualization using silhouette edges and advanced illumination such as ambient occlusion.We also present informal feedback received from the application scientists who use these methods in their workflow.