High-quality Volume Rendering of Adaptive Mesh Refinement Data

Adaptive mesh refinement (AMR) is a numerical simulation technique used in computational fluid dynamics (CFD). By using a set of nested grids of different resolutions, AMR combines the simplicity of structured rectilinear grids with the ability to adapt to local changes in complexity in the domain. Without proper interpolation on the boundaries of grids of different levels of a hierarchy, discontinuities can arise. Treating locations of data values given at cell centers of AMR grids as vertices of a dual grid creates gaps between hierarchy levels. Using an index-based tessellation approach that fills these gaps with “stitch cells” we define an interpolation scheme that avoids discontinuities at level boundaries. We use the resulting interpolation scheme to generate volume-rendered images. Modifying transfer functions on a per-level basis allows us to emphasize (or de-emphasize) a specific level and gain a better understanding of the underlying hierarchical structure.