Mask To Volume Mesh

The Mask To Volume Mesh tool converts the target mask(s) into conforming tetrahedral meshes and creates new volume mesh objects from them. Volume meshes are used for finite element analysis (FEA), computational fluid dynamics (CFD), and other simulation applications that require volumetric discretization.

Accessing the Tool

1. Navigate to the Segmentation tab in the ribbon.
2. Click Mask To Volume Mesh in the Convert section.

Parameters

Target Object(s)

Option	Description
Active mask	Convert the active mask only.
Selected masks	Convert all selected masks.
Visible masks	Convert all visible masks.
All masks	Convert every mask in the project.

Algorithm

Parameter	Description
Method	Grid3D — The only meshing method available for masks. Grid-based tetrahedral mesh generation.
Output mesh element type	Tetra 4-node — Linear tetrahedral elements. Quadratic 10-node — Quadratic tetrahedral elements with mid-edge nodes.

Meshing Parameters

The tool provides advanced meshing parameters through an embedded control panel. These parameters control mesh density, quality, and generation behavior. Refer to the meshing parameters section for detailed parameter descriptions.

info

Note: Unlike the Surface To Volume Mesh tool which offers both Auto3D and Grid3D methods, the Mask To Volume Mesh tool uses only the Grid3D method.

Workflow

1. Open the Mask To Volume Mesh tool from the Segmentation tab.
2. Select the Target Object(s) to convert.
3. Confirm the Method is set to Grid3D (the only option for masks).
4. Select the Output mesh element type (Tetra 4-node or Quadratic 10-node).
5. Configure the Meshing Parameters to control mesh density and quality.
6. Click Apply to generate the volume mesh(es).

The new volume mesh object(s) appear in the Object Browser.

Mesh Generation Method

The Grid3D method:

• Generates tetrahedral meshes directly from the mask voxel grid
• Produces conforming meshes that respect the mask boundaries
• Works efficiently with voxelized data
• Suitable for both uniform and adaptive mesh generation

Element Types

Element Type	Description	Use Case
Tetra 4-node	Linear tetrahedral elements with 4 nodes (one at each corner).	Faster computation, suitable for most analyses.
Quadratic 10-node	Quadratic tetrahedral elements with 10 nodes (4 corners + 6 mid-edge nodes).	Higher accuracy for curved boundaries and stress concentrations.

Volume Mesh Quality

Tetrahedral quality is measured by element shape:

• High quality: equilateral tetrahedra
• Low quality: flat or degenerate tetrahedra

Poor quality elements can cause:

• Numerical instability in simulations
• Inaccurate results
• Solver convergence issues

Use Cases

Finite Element Analysis

Prepare models for structural analysis:

1. Segment the structure of interest.
2. Generate volume mesh with appropriate element size.
3. Export in compatible format (VTK, INP, etc.).
4. Import into FEA software.

Biomechanical Simulation

Create patient-specific models for:

• Bone stress analysis
• Soft tissue deformation
• Implant design verification

Computational Fluid Dynamics

Generate meshes for flow analysis:

• Blood flow simulation
• Airway analysis
• Thermal modeling

Output Format

The generated volume mesh includes:

• Nodes: 3D coordinate points
• Elements: Tetrahedral connectivity
• Surfaces: Boundary triangles (optional)
• Material regions: For multi-label masks

Post-Processing

After generation, the volume mesh can be:

• Exported to various simulation formats
• Refined in specific regions
• Assigned material properties
• Processed with Volume Mesh tab tools

Tips

• Smooth the mask before conversion for better mesh quality.
• Start with Tetra 4-node elements for faster processing, then switch to Quadratic 10-node if higher accuracy is needed.
• Adjust meshing parameters to control element density in different regions.
• Verify mesh quality before using in simulations.
• For complex geometries, consider converting to surface first, optimizing it, then using Surface To Volume Mesh.

warning

Volume mesh generation for large masks can be computationally intensive and may require significant time and memory. Consider using resolution reduction in the mask preprocessing if needed.

tip

For multi-label masks, each label region will be meshed separately, creating conforming volume meshes that share boundary nodes.

See Also

• Mask To Surface — Create surface meshes.
• Volume Mesh Tab — Volume mesh processing tools.
• Smooth Mask — Pre-smooth masks for better mesh quality.
• Segmentation Tab Overview — Overview of all segmentation tools.