DIRSIG4 allows users to create voxelized geometry. This consists of a series of regularly spaced boxes. A unique material, temperature, and concentration can be assigned to each box.
This functionality is useful for integrating the output of external models with DIRSIG. For example, the output from a plume model can be converted to the DIRSIG voxelized grid format and rendered in a scene.
Note that voxelized geometry is still experimental; the file formats and methods for specifying the grid are liable to change in the near future.