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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.

A cross-section of a surface mesh, which is only the boundary, next to a volume mesh whose elements fill the interior, with the boundary faces marked

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)​

OptionDescription
Active maskConvert the active mask only.
Selected masksConvert all selected masks.
Visible masksConvert all visible masks.
All masksConvert every mask in the project.

Algorithm​

ParameterDescription
MethodGrid3D: the only meshing method available for masks. Grid-based tetrahedral mesh generation.
Output mesh element typeTetra 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 Scene Tree.

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

A linear tetrahedron with four corner nodes next to a quadratic tetrahedron with the same four corners and six additional mid-edge nodes

Volume Mesh Quality​

Tetrahedral quality is measured by element shape:

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

A regular, a stretched and a sliver tetrahedron with their edge ratio and smallest dihedral angle measured on the drawn elements

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​