Volume Dataset Portal
Here are some links to sites offering free volume datasets. If you know of any other dataset download sites, please get in touch and I'll update the list.
Stanford Volume Data Archive
Includes CThead, MRbrain and the Stanford Bunny.UNC Chapel Hill Volume Rendering Test Data
Original UNC test data archive. Includes CThead, MRbrain, 3Dhead (MRbrain without brain exposed) and 3Dknee.Stefan Roettger's Dataset Collection
Vast disparate collection of sampled and simulated datasets.Chris Rorden
Includes CThead, 3Dhead, Engine Block as well as a daisy pollen, mouse embryo and MRI angiogram.VolVis.org
Disparate collection of sampled and simulated datasets.Andreas Bærentzen
Includes the cartoon bear.Department of Radiology, University of Iowa
Collection of 8-bit medical datasets.Laboratory of Neuro Imaging, UCLA
Multi-modal human, mouse, monkey and rat datasets.SciDAC Ultra-scale Visualization Institute
Turbulent combustion simulation (time-varying dataset).vlib Datasets
My own collection. These datasets are all formatted with the vlib file header which can be removed easily if required.
Please respect any copyright, usage or redistribution restriction imposed by the dataset creators and give appropriate acknowledgement if these datasets are used to produce any published work.