VTK Legacy .vtk
Serial single-dataset format with an ASCII header naming POINTS, CELLS and CELL_TYPES; ASCII or binary body.
VTK RectilinearGrid .vtr
XML VTK file for grids with independent per-axis coordinate arrays; appended or inline base64 data.
VTK PolyData .vtp
XML VTK file for points, lines, polygons and strips, with named point and cell data arrays.
Wavefront OBJ .obj
Line-oriented ASCII geometry: v/vn/vt records and f faces with 1-based, optionally negative indices.
Stanford PLY .ply
Self-describing element lists declared in an ASCII header, followed by ASCII or packed binary property data.
STL .stl
Unstructured triangle soup with a normal per facet and no vertex sharing; ASCII or 80-byte-header binary.
3MF .3mf
The slicer's file: a ZIP of XML objects, assemblies placed by transform, materials as colours, a unit on the model.
OFF .off
An OFF magic line, a counts line, then vertices and faces; ST/C/N/4 prefixes add texture, colour and normals.
Abaqus .inp
Keyword-driven input deck: *NODE and *ELEMENT carry the mesh, *NSET and *ELSET the named collections.
AVS-UCD .avs
A five-integer counts line, then node records and cells keyed by a shape word, then optional data sections.
Medit binary .meshb
A stream of keyword-indexed fields; typed entity blocks carry node indices plus a trailing reference tag.
Medit ASCII .mesh .medit
Named sections of entity records, each ending in the reference integer that carries its surface or region label.
DOLFIN / FEniCS XML .xml
A small XML tree whose celltype names the element; every vertex and cell is explicitly indexed and 0-based.
FLAC3D .f3grid
Keyword-led ASCII records: G gridpoints, Z zones, F faces, with ZGROUP and FGROUP naming the regions.
glTF 2.0 .gltf .glb
JSON scene graph with PBR materials, animations and a binary buffer; GLB packs everything into one self-contained file.
COLLADA .dae
XML libraries of geometries, effects, skins and animations tied by #id; nodes spell transforms as matrix, translate, rotate, scale.
Gmsh .msh
$Section blocks for format, nodes, elements and physical names; v4.1 regroups them per entity, so parsing forks.
Nastran .bdf .nas .fem .dat
A deck of fixed-column cards in three coexisting field widths; GRID defines points, C* cards define elements.
Tecplot ASCII .tec .dat
A VARIABLES list then ZONE records; DATAPACKING decides whether values interleave per node or per column.
SU2 .su2
Plain ASCII keyed by uppercase tokens; elements carry a VTK type code, and boundaries are declared per marker.
TetGen .ele + .node
Sidecar files sharing a basename; the first index in the file decides whether numbering is 0- or 1-based.
Well-Known Text .wkt
The OGC text encoding: a type keyword and parenthesised coordinate lists, with EWKT adding an SRID prefix.
VTK UnstructuredGrid .vtu
XML VTK file for an arbitrary mix of cell types, with connectivity, offsets and per-cell type codes.
VTK StructuredGrid .vts
Curvilinear grid: explicit coordinates, implicit connectivity, expanded to hexahedra on read.
VTK ImageData .vti
A uniform grid stored entirely as metadata: origin, spacing and extent, with no coordinate array at all.
VTKHDF .vtkhdf
VTK's own HDF5 layout: an UnstructuredGrid, PolyData or ImageData under /VTKHDF, partitioned, with its time steps inside.
PVD (ParaView collection) .pvd
An XML index of VTK datasets over time, each with its timestep, part and group; read at one step or as a whole series.
MFEM mesh .mesh
Named sections keyed by a geometry type code; INLINE and NURBS variants carry a recipe, not a mesh.
Netgen .vol
Counted sections whose leading fields differ per section; bcnr / matnr indices come back as named tags.
UGRID (AFLR) .ugrid
Seven header counts and nothing else separating the sections; surface IDs sit between faces and cells.
Gaussian splat .splat
Headerless 32-byte records: position, scale, colour and a packed rotation quaternion. Points only, no elements.
PCD .pcd
The Point Cloud Library's format: typed fields per point, ascii, binary or LZF-packed bodies, organised clouds, a sensor viewpoint.
LAS / LAZ .las .laz
The LiDAR exchange format: scaled integer coordinates, point formats 0 to 10, extra bytes, a CRS in WKT or GeoTIFF keys, LAZ compression.
ASCII point cloud .xyz .pts .ptx
Columns of numbers: coordinates, intensity, colour, normal.
Leica's counted .pts and per-scan .ptx with its pose.
Kratos MDPA .mdpa
Begin/End blocks with no counts: nodes, elements named by Kratos element class, conditions, data and sub model parts.
PERMAS .dato .post .dat
$KEYWORD records running to the next $: $COOR nodes, $ELEMENT blocks named by solver class, $NSET and $ESET groups.
ANSYS Fluent .msh .fluent
Parenthesised sections in hex: nodes, faces naming the cell on either side, zones by name; cells are assembled from their faces.
SVG .svg
A picture, write-only: the mesh projected onto a plane, one path per element type, lines and faces outlined in mesh units.
XDMF .xdmf .xmf
XML light data over HDF5, binary or inline arrays: mixed topologies, lattices, sets, and a time series read one step at a time.
MED .med
Salome's and code_aster's HDF5 file: families and groups as tags, fields on nodes, cells and Gauss points, several meshes merged.
CGNS .cgns
The CFD standard in HDF5: every zone read and tagged, MIXED and NGON sections, boundary conditions as tags, solutions as attrs.
H5M .h5m
MOAB's native file: handle ids resolved, dense tags as attrs, meshsets as named tags with their material or boundary number.
HMF .hmf
XDMF's model in one HDF5 file: typed topologies, node and cell attributes, plus sets and mesh-wide values.
Exodus II .e .exo .ex2
Sandia's netCDF finite element database: blocks and sets as tags, side sets as faces, results at one time step.