VTV-AMR: Visualization of Time-Varying Adaptive Mesh Refinement Data

Adaptive mesh refinement (AMR) is used by 3D computational fluid dynamic (CFD) solvers to focus the computation on interesting regions in space (and time). Popular AMR codes that were, e.g., used to produce the two data sets seen on this page are NASA's LAVA fluid solver or FLASH by the University of Rochester. Examples of AMR topologies are Octrees, but other tree types, branching factors, shapes, etc. are possible.

AMR codes virtually always store the data (density, temperature, velocities, etc.) at the "cell centers". For that, imagine the cell to be a small box. "Vertex-centric" methods associate the data with the box corners, while "cell-centric" means the data is stored at the center of the box. Efficient and high-quality visualizations usually have to reconstruct the data at arbitrary sample points and for that need to be able to quickly identify rectangular neighborhoods.

In VTV-AMR, our focus is on crack-free visualizations with state-of-the-art GPU ray tracing technology to produce high-quality renderings, and hence we have to use auxiliary data structures; unfortunately, the memory footprint and construction times of such data structures are not targeted at real-time performance, nor at time-varying data comprised of multiple simulation time steps with adaptively changing AMR grids. 

Our contributions will advance the state-of-the-art in high-quality AMR data reconstruction of cell-centric data on GPUs to interactively visualize data sets composed of 100s to 1000s of time steps. We focus on data where even single time steps saturate most of the available GPU memory. For that, we build on state-of-the-art software solutions that were recently published in leading international research journals, and that we will extend to support time-varying data. 

The "NASA exajet" data set is courtesy Pat Moran. The molecular cloud data set is reused with friendly permission by Daniel Seifried with the Theoretical Astrophysics Group of the University of Cologne. For more visualizations, check out the Visualizations subpage.