1. An article comprising a tangible, non-transitory machine-readable medium that stores a program, the program being executed by a machine having a hardware component to perform a method, the method comprising: associating multiple colors in a color map to respective ranges of volumetric density measures; receiving a volume dataset defining a volume; and rendering a view of a dataset, wherein a voxel visualized in the view has a value that is dependent upon a heterogeneity of the voxel at a sample location, the heterogeneity being calculated by taking a sum of a difference between a sampled voxel and its neighbor voxels; the voxel having a color that is a selected one of the multiple colors, the color being selected by using the value to perform a lookup into the color map; wherein the view comprises multiple voxels, wherein the number of neighbor voxels used to determine the values of the voxels varies across the view.