VTK / Mesh Preview

The same viewer opens every common VTK-family and surface-mesh format. All of the feature set — outline & layers, mesh quality, field visualization, editing & history, MMG remeshing, navigation — works here too; point / cell data arrays from any format appear in the Field panel.

Supported formats

Format	Extensions	Notes
Legacy VTK	.vtk	ASCII and binary (big-endian) unstructured grids
VTK XML	.vtu, .vtp, .vti, .vts, .vtr	ascii, inline base64, appended raw / base64, zlib-compressed
VTK multiblock	.vtm	referenced blocks merge into one scene; each block becomes a layer
Surface meshes	.stl (ascii + binary), .obj, .ply (ascii + binary)	STL vertices are welded; OBJ g / o groups become named layers; PLY vertex properties become fields
Extended (meshio++)	.msh (Gmsh), .inp (Abaqus), .bdf / .nas / .fem (Nastran), .unv, .mesh (Medit), .vol (Netgen), .su2, .xdmf / .xmf, .off, .dat / .tec (Tecplot), .avs, .f3grid, .pf3, .mfm, .mphtxt (COMSOL), .post / .dato (PERMAS), .ugrid, .wkt, .xml (DOLFIN), .node / .ele (TetGen)	Read through @meshioplusplus/wasm. Ambiguous extensions are resolved by content: .msh tries Gmsh then ANSYS / FreeFem, .inp tries Abaqus then ANSYS. TetGen reads its .node / .ele pair together
HDF5 / netCDF containers (meshio++)	.cgns, .h5m (MOAB), .hmf, .med (Salome), .e / .exo / .ex2 (Exodus II)	Need a meshio++ >= 8.0.0 build (Exodus >= 9.3.0 for particle meshes). .med is read-only: its WebAssembly writer rejects a mesh carrying data arrays. Exodus can be written but lossily — SubModelParts and time steps do not survive it. Exodus carries its own in-file time series, and its SPHERE elements render as spheres. An .xdmf using HDF storage is opened together with its companion .h5

Open any of them from the explorer context menu (Open VTK Preview), the editor-title button, or the Kratos VTK: Open VTK Preview command.

Multiblock (.vtm)

A .vtm index references child datasets by slash-path; the extension merges them into one scene (node / entity ids offset per block), prefixes each block's name, and emits one SubModelPart per dataset — so every block is an independently toggleable layer. Paths that try to escape the .vtm directory are rejected.

Surface meshes

• STL — ascii and binary, with a byte-size cross-check (binary headers may start with solid); vertices are welded on a 6-decimal coordinate key.
• OBJ — v / f (slash forms, negative indices, fans) / l / p, with g / o groups becoming named blocks.
• PLY — ascii and binary (LE / BE); extra numeric vertex properties become Nodal fields (plot them via Field), and edge elements become line cells.

Surface formats always open as a single static view (no timeline).

Kratos time series

Kratos writes one VTK file per model-part per time step (e.g. Main_0_2.vtk, Main_FixedEdgeNodes_0_4.vtk). Open any file in such a series and the extension detects the pattern and loads the whole series with a scrubber — see Time-series Playback.

SubModelpart tree

The sidebar shows the same layer tree as the MDPA preview. The root model-part file provides the full mesh; each submodelpart file (e.g. FixedEdgeNodes, MovingNodes) appears as a hidden-by-default overlay layer you can toggle independently. Node-only submodelparts are rendered as vertex points.

Known limitations

• MPI rank > 0 files are not merged in this release (rank-0 files are loaded).
• Submodelpart merging uses coordinate matching (toFixed(6)); if the root and subpart files were written at different float precision the merge may miss nodes (a diagnostic is emitted in the sidebar stats).

Named groups become SubModelParts

Formats that carry named groups deliver them straight into the outline tree as SubModelParts — gmsh physical groups, Abaqus *NSET / *ELSET / *SURFACE, and every other group meshio++ recognizes. They behave exactly like a .mdpa SubModelPart: toggle, frame, rename, delete, or export one on its own.

A group of cell facets (an Abaqus *SURFACE, an Exodus side set) is materialized into real boundary facets emitted as Conditions, so the surface is a layer you can see rather than a list of indices — and exporting to .mdpa produces genuine Kratos Conditions.