The UltraVis system is a free software system for fast and versatile volume rendering. UltraVis is a software system for fast and versatile volume rendering on standard PCs. Volume rendering means the display of a three-dimensional array of data.

UltraVis currently supports seven voxel formats:
1. 8-bit scalar value
2. 12-bit scalar value
3. 8-bit scalar value plus 4-bit material label
4. 8-bit scalar value plus precomputed gradients (8 bits per component)
5. 7-bit scalar value, precomputed gradients (7 bits per component) plus 4-bit material label
6. RGBA-voxels (8 bits per component)
7. RGBA-voxels (7 bits per component) plus 4-bit material label

Maximum data set dimensions are 256x256x256.

UltraVis Additional Features:
1. Perspective Raycasting
2. Tri-linear Interpolation or Nearest-Neighbor Sampling
3. Early Ray Termination
4. Empty Space Skipping
5. Subsampling during Motion, Nearest-Neighbor Sampling during Motion
6. On-the-fly Classification via Look-up Tables
7. Diffuse and Specular Shading using four Light Sources
8. Alpha-Compositing
9. Support for up to 16 different Materials in a Data Set
10. Multiple Sessions
11. Volume Animation
12. Support for Stereo Viewing (some restrictions apply)
13. Network Operation for Parallel Rendering

The license of this software is Freeware, you can free download and free use this graphing software.