Institute for Data Analysis and Visualization

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 structu red rectilinear grids with the ability to adapt to local changes in complexity in th e domain. Without proper interpolation on the boundaries of grids of different lev els of a hierarchy, discontinuities can arise. Treating locations of data values giv en 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.