Recipe: VTK or binary artifacts

Goal: go from running code to files on disk you can open in ParaView or analyze offline.

Path A — VTK (ParaView / VisIt)

Best for interactive 3D visualization without writing parsers.

  1. Follow tutorials/vtk_paraview_workflow.md (runs 11_write_results / 12_cahn_hilliard-style flows).

  2. Writers overview: io_results.md (VTKWriter is typically wired in code for examples).

Path B — Raw binary (MPI-IO)

Best for restarts and custom post-processing; no file header — you need sidecar metadata.

  1. Normative layout: binary_field_io_spec.md.

  2. Offline sketches (Python, caveats): postprocess_binary_fields.md.

  3. End-to-end narrative with a small app: tutorials/end_to_end_visualization.md.

Path C — PNG (2D quick look)

Small grayscale snapshots (e.g. Allen–Cahn app): see io_results.md and applications.md.

Checklist before debugging “empty files”

  • Same MPI for build and run; writers are often collective — all ranks must participate (mpi_io_layout_checklist.md).

  • Paths in JSON point to a writable directory from the job’s cwd.