MMG3D(1)

💖 MMG3D 💖

okay bestie, so this is the page for mmg3d, and it lives in the General Commands Manual — section 1, no cap. it's giving mesh wizardry, and i'm gonna walk you through every single flag so you don't have to squint at it alone 🫶

---

✨ NAME ✨

mmg3d — adaptation and optimization of a tetrahedral mesh and implicit domain meshing. that's the whole pitch, short and iconic 💅

---

🦋 SYNOPSIS 🦋

mmg3d ⟨mesh_file⟩ [output_file] [-sol ⟨solution_file⟩]
      [-met ⟨metric_file⟩] [-h] [-v] [-m ⟨n⟩] [-d] [-val] [-default]
      [-A] [-ar ⟨x⟩ | -nr] [-hmin ⟨x⟩] [-hmax ⟨x⟩] [-hsiz ⟨x⟩]
      [-hausd ⟨x⟩] [-hgrad ⟨x⟩] [-hgradreq ⟨x⟩] [-rmc x] [-opnbdy]
      [-lag ⟨n⟩] [-ls x] [-lssurf x] [-nofem] [-noinsert] [-nomove]
      [-noswap] [-nosurf] [-nosizreq] [-nreg] [-xreg] [-nsd] [-optim]
      [-optimLES] [-octree ⟨n⟩] [-rn ⟨n⟩]

---

🌸 DESCRIPTION 🌸

the mmg3d application is dedicated to tetrahedral remeshing. and not just one mesh — both the surface mesh and the volume mesh get modified. equal opportunity glow-up ✨

by default it performs mesh modifications in order to control the surface approximation. that's the out-of-the-box behaviour, no extra input needed.

hand it a metric file and it adapts the mesh to the prescribed sizes at nodes. very "i have opinions about your edge lengths" of it 🎀

without a metric file, the -optim option lets it improve the mesh quality with respect to the initial mesh size. and the -optimLES option? that one improves strongly the isotropic mesh quality for LES simulations. main character energy fr fr 🔥

now, if you give it a level-set file containing the values of the level-set function at the mesh nodes, the -ls option lets you explicitly mesh an implicit domain, and -lssurf splits mesh boundaries on a provided isovalue. so many doors opening 🌈

and if you provide a displacement file, -lag applies a lagrangian displacement to boundary mesh nodes. wig. 💫

---

🎀 COMMAND LINE ARGUMENTS 🎀

1. Generic options

• -h — print help. your safety net when you're lost 💀
• -v ⟨n⟩ — tune level of verbosity. takes values between -1 and 10.
• -m ⟨n⟩ — set maximal memory size to n MBytes.
• -d — turn on debug mode. bring a snack, it's chatty 🍓
• -default — write a local parameter file (with extension .mmg3d) with setted values.
• -val — print the default parameters values.

2. File specifications

• -in ⟨mesh_file⟩ — input triangulation.
• -out ⟨output_file⟩ — output triangulation.
• -sol ⟨solution_file⟩ — load metric, displacement or level-set file.
• -met ⟨metric_file⟩ — load metric file in level-set mode.

3. Mode specifications (default is mesh adaptation)

• -lag ⟨n⟩ — Lagrangian mesh displacement according to mode 0 ( n=0 ), 1 ( n=1 ) or 2 ( n=2 ). this option is only available with the USE_ELAS compilation flag. the LinearElasticity library must be founded to activate this flag. no flag, no vibes, sorry 😭
• -ls x — create mesh of isovalue x (0.0 if x is not provided).
• -lssurf x — split boundary mesh on isovalue x (0.0 if x is not provided).

4. Parameters

• -A — enable anisotropy (without metric file).
• -ar ⟨x⟩ | -nr — threshold for angle detection, or sharp features detection disabling.
• -hmin ⟨x⟩ — minimal mesh size.
• -hmax ⟨x⟩ — maximal mesh size.
• -hsiz ⟨x⟩ — constant mesh size.
• -hausd ⟨x⟩ — control the Hausdorff distance between the surface mesh and the underlying surface geometry.
• -hgrad ⟨x⟩ — control the gradation.
• -hgradreq ⟨x⟩ — control the gradation from required entities toward others.
• -rmc x — remove componants whose volumic fraction is less than x (1.e-5 if x is not provided) of the whole mesh volume (level-set mode).
• -opnbdy — preserve input triangles at the interface of two domains of the same reference.
• -nofem — do not force Mmg to create a finite element mesh.
• -noinsert — no point insertion/deletion.
• -nomove — no point relocation.
• -nosurf — no surface modifications.
• -noswap — no edge or face flipping.
• -nosizreq — no imposition of the size of required edges over required vertices.
• -nreg — normal regularization using laplacian - antilaplacian smoothing.
• -xreg — vertex coordinates regularization using laplacian - antilaplacian smoothing.
• -nsd ⟨n⟩ — save the subdomain of index n (default is n=0 which save all subdomains).
• -octree ⟨n⟩ — specify the maximal number of point per octree cell (only available without the PATTERN compilation flag).
• -optim — mesh improvement with respect to the initial mesh size.
• -optimLES — strong isotropic mesh optimization for LES computations.
• -rn ⟨n⟩ — turn on ( n=1 ) or off ( n=0 ) the renumbering using the SCOTCH library (only available with the USE_SCOTCH compilation flag and if the scotch library is founded).

---

💜 RETURN VALUES 💜

mmg3d returns:

• the 0 value if successful; 🎉
• the 1 value if the process fail but can save a conform mesh;
• the 2 value if the process fail and can't save a comform mesh. 💀

---

👑 SEE ALSO 👑

mmgs(1) mmg2d(1) — go say hi to the siblings, they're family 🫶

---

and that's the whole page, bestie!! this one's the mmg3d page, version/date stamped May 04, 2015, footer label MMG3D(1) — the mmg3d tool, dated May 04, 2015, tagged MMG3D(1). go forth and remesh, you absolute icon 💅✨🌸