The VDB Convert operator can be used to convert SDF voxels to Density voxels and vice versa.
SDF to Density: converts an SDF grid to a density grid. Density grid values will correspond to SDF distance values (densities will be higher for cells closer to SDF surface).
Density to SDF: converts a density grid to an SDF grid by constructing an implicit mesh from the density grid and deriving an SDF from the mesh.
Rebuild SDF: rebuilds an SDF grid by constructing an implicit surface from the SDF and then re-calculating the SDF values for each cell in the grid based on their distance to the surface.
SDF/Density grid name: the names of the source VDB grids.
Iso value: controls the iso value for density grid conversion. Higher values bias the surface level towards higher densities.
Keep grid sparse: when enabled, simplified voxel groups in the VDB tree will not be broken up into individual voxels.
“Keep grid sparse” can reduce memory usage, but if voxels values are significantly changed in some way (ex: displaced), large square artifacts can appear in the grid.