Is voxel rendering a form of volume rendering?

Question

When reading about volume rendering, I see voxel rendering is mentioned a lot. I know volume data have voxels, but are the two terms interchangeable, or are they completely different?

Answer 1

They are not interchangeable, but neither completely different. As your question title says, voxel rendering is a form of volume rendering, as it renders a volume. You can visualize volumetric data with a variety of methods, voxel rendering being one.

EDIT: You should also beware that sometimes people use the term volume rendering for algorithms that just render a set of discrete volume elements (voxels) and therefore really interchangeably to voxel rendering. But sometimes use it to refer to the more general visualization of 4 (or higher) dimensional data (as it arises e.g. from medical or geographical imaging precesses), which is rarely done by traditional voxel rendering (rendering small "boxes").

You should not use volume rendering and voxel rendering interchangeably, as the former is a much broader and more general topic.

Answer 2

All this confusion about "voxel rendering" goes back to the early 90s and the Commanche series of helicopter flight-simulation games; these claimed to use a "voxel terrain engine". To anyone familiar with computer graphics algorithms, "2.5D height field raycaster" would have been a far more accurate/descriptive designation, but somehow the "voxel rendering" marketing buzzword-speak has stuck and become associated with that particular terrain rendering method as much as with volume rendering, resulting in confusion ever since.