MMG Parameters Reference¶

import pyvista as pv
import mmgpy  # noqa: F401  -- registers reader/writer + .mmg accessor
mesh = pv.read("input.mesh")

Complete reference for the keyword arguments accepted by dataset.mmg.remesh(...) (and its variants remesh_optimize, remesh_uniform, remesh_levelset, move). Each call returns a fresh PyVista dataset; the input is not mutated.

Size Parameters¶

hmin¶

Minimum edge length.

remeshed = mesh.mmg.remesh(hmin=0.01)

Edges shorter than hmin will be collapsed or lengthened.

hmax¶

Maximum edge length.

remeshed = mesh.mmg.remesh(hmax=0.1)

Edges longer than hmax will be split.

hsiz¶

Uniform target edge size.

remeshed = mesh.mmg.remesh(hsiz=0.05)

When set, overrides hmin and hmax with uniform sizing.

hgrad¶

Gradation parameter controlling size transition.

remeshed = mesh.mmg.remesh(hgrad=1.2)

• hgrad=1.0: No size variation allowed
• hgrad=1.3: Default, allows 30% size change between adjacent edges
• hgrad=2.0: Large size variations allowed

Geometric Parameters¶

hausd¶

Hausdorff distance, maximum distance between input and output geometry.

remeshed = mesh.mmg.remesh(hausd=0.001)

Smaller values produce a closer geometric approximation at the cost of more elements.

ar¶

Ridge detection angle (degrees).

remeshed = mesh.mmg.remesh(ar=30)

• Edges with dihedral angle greater than ar are treated as ridges and preserved during remeshing.
• ar=180 disables ridge detection.

Control Flags¶

optim¶

Enable optimization mode (no topology changes).

remeshed = mesh.mmg.remesh(optim=1)

When enabled, only moves vertices to improve quality.

noinsert¶

Disable vertex insertion.

remeshed = mesh.mmg.remesh(noinsert=1)

Prevents adding new vertices during remeshing.

noswap¶

Disable edge/face swapping.

remeshed = mesh.mmg.remesh(noswap=1)

Prevents topology changes via edge/face swaps.

nomove¶

Disable vertex movement.

remeshed = mesh.mmg.remesh(nomove=1)

Keeps vertices at their original positions.

nosurf¶

Preserve surface vertices.

remeshed = mesh.mmg.remesh(nosurf=1)

Prevents modification of surface mesh vertices.

Output Control¶

verbose¶

Verbosity level.

silent = mesh.mmg.remesh(verbose=-1)  # Silent
errors = mesh.mmg.remesh(verbose=0)   # Errors only
info = mesh.mmg.remesh(verbose=1)     # Standard info
debug = mesh.mmg.remesh(verbose=5)    # Debug output

Common Combinations¶

Quality optimization only¶

optimized = mesh.mmg.remesh(optim=1, noinsert=1)

Or use the convenience method:

optimized = mesh.mmg.remesh_optimize()

Uniform remeshing¶

uniform = mesh.mmg.remesh(hsiz=0.05)

Or use the convenience method:

uniform = mesh.mmg.remesh_uniform(size=0.05)

High-quality surface approximation¶

remeshed = mesh.mmg.remesh(
    hmax=0.1,
    hausd=0.0001,  # Tight geometric tolerance
    hgrad=1.1,     # Smooth size transition
)

Preserve sharp features¶

remeshed = mesh.mmg.remesh(
    hmax=0.1,
    ar=20,         # Detect more ridges
    hausd=0.001,
)

Fast coarse remeshing¶

remeshed = mesh.mmg.remesh(
    hmax=0.5,
    hgrad=2.0,     # Allow large size variations
    verbose=-1,
)

Volume interior only¶

remeshed = mesh.mmg.remesh(
    hmax=0.1,
    nosurf=1,      # Keep surface fixed
)

Parameter Interactions¶

Best Practices¶

1. Start with defaults, MMG auto-computes reasonable values.
2. Set hmax first, it is the most important parameter.
3. Add hausd for surfaces, it controls geometric fidelity.
4. Tune hgrad, lower values give smoother transitions.
5. Use verbose=-1 for batch processing.
6. Validate results with dataset.mmg.validate(detailed=True) after remeshing.