Research Highlights

I also maintain a complete list of publications and talks.

When representing numeric values as colors, the choice of color has a dramatic affect on the interpretation back to numbers. This work collects a series of color ranges that are known to have good properties when mapping scalar fields to colors. Use this as a reference when creating scientific visualizations.
A common practice in studying the scaling performance of large scale parallel algorithms is to look at the behavior of the running time as the number of processing elements changes. This is a very poor way to analyze scaling behavior as good scaling and bad scaling can be visually indistinguishable from each other. This paper demonstrates the problems with using running time to study scaling and describes other metrics, easily derived from running time, that do a much better job characterizing scaling performance.
Designing the appropriate mapping from values to colors requires a mix of expertise in visualization, color, and perception. Most visualization users and many visualization experts lack the necessary background to design effective color maps. Consequently, many visualizations default to a color map infamous for its ineffectiveness: the rainbow color map. This work provides a method to easily generate a continuum of colors that yield effective and perceptually correct color mapping. In particular, the provided cool to warm color map makes for a good general default color map.
As accelerator processors such as GPUs become more prevalent in HPC, the need for running visualization algorithms that process and generate mesh topologies using massive amounts of execution threads becomes ever more pressing. Breaking a mesh into constituent elements to feed input of these threads is straightforward. However, many algorithms require the coordination and combination of results generated in disparate threads. This work provides the basic programming pattern that can be applied to numerous such algorithms. This critical technique is demonstrated on a variety of algorithms including marching cubes, subdivision, and dual grid generation.
The most common abstraction used by visualization libraries and applications today is what is known as the visualization pipeline. The visualization pipeline provides a mechanism to encapsulate algorithms and then couple them together in a variety of ways. The visualization pipeline has been in existence for over twenty years, and over this time many variations and improvements have been proposed. This paper provides a literature review of the most prevalent features of visualization pipelines and some of the most recent research directions.
In this work we demonstrate running the scalable rendering library IceT at scale on a large supercomputer. Along the way we introduce several simple to implement but powerful sort-last parallel rendering modifications that greatly improve the efficiency including minimal copy image interlacing for better load balancing and telescoping compositing for arbitrary job sizes. Visit the IceT project page for access to the software, documentation, and further papers and information on scalable rendering.
This is, to the best of my knowledge, the first publication describing implementing the Fast Fourier Transform algorithm on a modern graphics processor. The work predates general GPU languages like CUDA and OpenCL, so this implementation uses an older shader language called Cg. Since this paper there have been many improved implementations of the FFT algorithm, but the paper still provides some index manipulations and real transform symmetry encoding that can be useful.
Partial Pre-Integration is a technique to accelerate the radiative transfer computation used in volume rendering. The technique simplifies the complicated equations by collecting integrands with like parameters and evaluating them with universally applicable tables. (Note that Partial Pre-Integration is not the same as Pre-Integration, which precomputes all possible integrals in a parameter-specific table.)
SAND 2015-4836 W