Spatially Adaptive Volume Tools in Bifrost

The level set method offers many advantages over e.g. meshes for modelling and visual effects, but a naïve implementation is both computationally expensive and memory intensive. Narrow band level sets alleviate both issues but are still limited by the finest detail resolved due to uniform resolution along the surface. Voxel structures that are adaptive along the surface improve this [Frisken et al. 2000], but have not seen wide adoption. This is presumably due to difficulties matching the performance of optimized narrow band implementations like industry standard OpenVDB [Museth 2013]. We present the adaptive level set implementation in Bifrost which is competitive with OpenVDB in speed while offering lower memory usage thanks to spatial adaptivity. Our contributions include novel algorithms for adaptive sharpened B-spline interpolation of volumes in general, voxelizing meshes and points into adaptive level set volumes, and meshing adaptive level sets.