VTKHDF.jl

Write and read VTK data in the VTKHDF file format, the HDF5-based successor to the VTK XML formats. The files can be opened in ParaView, VisIt and VTK. The writing API follows WriteVTK.jl and shares its cell/data types through VTKBase.jl. vtkhdf_open reads those files back, and also spec-conforming files from other writers.

Why VTKHDF?

• Time series live in one file. The geometry of a fixed mesh is stored once and each step appends only its data — no more .pvd collections with one .vtu file per step.
• It is built on HDF5: standard tooling (h5dump, h5py, HDF5.jl) can inspect the files, and chunked storage and gzip compression are available.
• One format covers all the dataset types, from image data to composite multi-block datasets.

Installation

import Pkg
Pkg.add(url = "https://github.com/Ferrite-FEM/VTKHDF.jl")

Quick start

A grid is points plus cells connecting them. vtkhdf_grid writes them to a file; data arrays are attached by indexing:

using VTKHDF

points = [
    0.0 1.0 0.0 0.0
    0.0 0.0 1.0 0.0
    0.0 0.0 0.0 1.0
]
cells = [MeshCell(VTKCellTypes.VTK_TETRA, [1, 2, 3, 4])]

vtkhdf_grid("output", points, cells) do vtk
    vtk["temperature"] = [0.0, 1.0, 1.0, 1.0]   # one value per point
    vtk["material", VTKCellData()] = [1]        # one value per cell
end

This wrote output.vtkhdf, which can be opened in ParaView or VisIt. vtkhdf_open reads it back with the same indexing:

vtkhdf_open("output") do r
    r["temperature"]
end

4-element Vector{Float64}:
 0.0
 1.0
 1.0
 1.0

The Manual covers writing and reading all dataset types, including time series. The Examples section contains complete programs, one per reference file of the VTKHDF specification.

Supported dataset types

Temporal OverlappingAMR/HyperTreeGrid and MPI-parallel collective writing are currently out of scope (VTK's own writer does not produce them either).

Development

This package was mainly developed with AI assistance (Claude Code), guided by the VTKHDF specification, with the output validated against the VTK reference implementation.