A voxel volume is an object made of volumetric elements called voxels (volume pixels). Each voxel holds one value in a regular 3D grid, for example the density measured by a CT or MRI scanner. Unlike meshes and point clouds, a voxel volume describes the whole space inside its box, not only a surface or separate points. In the app this object type is called Voxel Volume.
Voxel volumes are characterized by:
- A regular 3D grid structure.
- A volumetric representation.
- Voxel-specific values, such as the voxel size and the value (density) in each voxel.
Voxel Volumes in MeshInspector
When you open a voxel volume, it appears in the Scene tree and in the viewport. In the Scene tree, its icon is three stacked cubes.
Two panels below the Scene tree describe the selected volume:
- Information shows Object Type (Voxel Volume), the size of the bounding box, Voxels Dims (the number of voxels along X, Y and Z), Voxel Size, the Active Box Min and Active Box Max (only when an active box is set) and Min,Iso,Max (the smallest value, the iso value and the largest value).
- Transform lets you scale, rotate and move the volume in 3D space.
How a volume is displayed
A volume is shown as an iso-surface: a surface that passes through the voxels whose value equals the iso value. Change the iso value, and with it the surface, with CT › Change ISO. Two more free tools show the inside of the volume:
- CT › Volume Rendering draws the voxels themselves, colored by value.
- CT › Voxels Slice shows a slice of the volume as an image, in the YZ, ZX or XY plane.
While Volume Rendering is on, Voxels Slice and Change ISO are not available.
The iso-surface is made of triangles. Press L to show or hide their edges; this shows the triangles of the surface, not the voxel grid.
On the Inspect tab, Object Info shows details of the volume: its dimensions, voxel size, active box, the minimum, iso and maximum values, the number of voxels and the memory use.
Open a voxel volume
| Data | How to open | Export |
|---|---|---|
| DICOM series (.dcm) | CT › Open DICOMs (select the folder) | Yes |
| RAW (.raw) | CT › Open RAW Voxels (enter the parameters of the file) | Yes |
| TIFF stack (.tif, .tiff) | CT › Open Voxels From TIFF | No |
| OpenVDB (.vdb) | Home › Open Files | Yes |
| Micro CT (.gav) | Home › Open Files | Yes |
Steps and settings: Open DICOMs, Open RAW Voxels and Open Voxels From TIFF.
You can also make a volume from other objects: Mesh Edit › Mesh to Voxels (Professional plan) and Lines › Lines to Voxels.
What you can do with a voxel volume
All voxel tools are on the CT tab:
| Task | Tools | Plan |
|---|---|---|
| View | Change ISO, Volume Rendering, Voxels Slice | Free |
| Analyze | Voxels Line Graph, Voxels Path | Professional |
| Prepare | Set Active Voxel Box, Voxels Resampling, Voxels Segmentation, Binary Operations | Professional |
| Adjust values | Voxels Normalize | Free |
Convert voxels to a mesh
CT › Voxels to Mesh (Professional plan) creates a mesh from the iso-surface of the selected volume. Set the iso value with Change ISO first: the mesh follows the same surface. See How to Convert Voxels to Mesh.
Save a voxel volume
- Export saves the selected volume as .vdb, .raw, .gav or .dcm.
- CT › Voxels Slice can save the current slice or all slices as images.
- Home › Save Scene saves the whole scene to a MeshInspector scene file (.mru).
Voxel volume options in the Scene tree
Right-click the volume in the Scene tree to change how its iso-surface is displayed (colors, opacity, shading, bounding box, clipping) and to Remove or Clone it. Every option is explained in Scene Tree Mastery.
