Supported File Formats¶

ORION supports multiple scientific data formats commonly used in computational fluid dynamics (CFD) and scientific visualization. This page provides detailed information about each supported format.

Format Overview¶

Format	Type	Extension(s)	Read	Write	Notes
Tecplot ASCII	Text	`.dat`, `.tec`	✅	✅	Human-readable, slower I/O
Tecplot Binary	Binary	`.plt`, `.szplt`	✅¹	✅¹	Compact, fast I/O
VTK	Text/Binary	`.vtm`, `.vts`	✅	✅	Open standard, widely supported
PLOT3D	Text	`.p3d`	✅	✅	NASA legacy format

¹ Requires building with --use-tecio flag

Tecplot Format¶

Tecplot is a proprietary data visualization format widely used in aerospace and CFD applications.

Format Types: - ASCII - Human-readable text format - Binary - Compact binary format (PLT, SZPLT)

Recommendations: - Use ASCII for small files and debugging - Use PLT for general production work - Use SZPLT for large datasets requiring compression

File Structure¶

Header:

VARIABLES = "X", "Y", "Z", "Pressure", "Temperature"
ZONE T="Block 1", I=50, J=50, K=50, F=POINT

Data: - Point or cell-centered - Structured grids - Multi-block support - Time-dependent data

Supported Features¶

Feature	ASCII	Binary	Notes
Structured grids	✅	✅	IJK-ordered data
Multi-block	✅	✅	Multiple zones
Variable data	✅	✅	Scalar and vector fields
Time series	✅	✅	Multiple solution times
Boundary conditions	❌	❌	Not yet supported
Unstructured	❌	❌	Not supported

VTK Format¶

VTK (Visualization Toolkit) is an open-source data format used by ParaView, VisIt, and other visualization tools.

Format Types: - Legacy formats - Text/Binary format (.vtk) - XML formats - Modern VTK formats (.vtm, .vts, .vtu)

File Structure¶

Header:

# vtk DataFile Version 3.0
ORION generated VTK file
ASCII
DATASET STRUCTURED_GRID
DIMENSIONS 50 50 50
POINTS 125000 float

Data: - Structured and unstructured grids - Point and cell data - Multiple scalar/vector fields

Supported Grid Types¶

Grid Type	Support	VTK Dataset Type
Structured grid	✅	`STRUCTURED_GRID`
Rectilinear grid	✅	`RECTILINEAR_GRID`
Polydata	⚠️	`POLYDATA` (read only)

PLOT3D Format¶

PLOT3D is a NASA-developed format for structured CFD data, still widely used in aerospace applications.

PLOT3D Files

ORION can work only with grid files.

Format Components: - Grid file (.p3d) - Mesh coordinates

File Structure¶

Grid File (.p3d):

Number of blocks
Block 1: I, J, K dimensions
Block 2: I, J, K dimensions
...
X coordinates for all blocks
Y coordinates for all blocks
Z coordinates for all blocks

Format Comparison¶

Feature Matrix¶

Feature	Tecplot	VTK	PLOT3D
Multi-block	✅	✅	✅
Grid + Solution	✅	✅	❌
Binary I/O	✅	✅	❌
Compression	✅	✅	❌
Metadata	✅	✅	❌
Time series	✅	✅	❌
Open format	❌	✅	✅

Use Case Recommendations¶

Use Tecplot when:

Working with commercial CFD software
Need advanced visualization features
Require time-dependent data

Use VTK when:

Need open-source compatibility
Using ParaView or VisIt
Sharing data openly

Use PLOT3D when:

Working with legacy NASA codes
Need compact structured grid format

Conversion Between Formats¶

Example Tecplot → VTK:

ORION --input-format tecplot --input-file data.dat \
      --output-format vtk --output-file output.vtk

See the converter guide for more details

Conversion	Mesh	Variables	Metadata
Tec → VTK	✅	✅	⚠️
VTK → Tec	✅	✅	⚠️
P3D → Tec	✅	❌	❌
Tec → P3D	✅	❌	❌
VTK → P3D	✅	❌	❌
P3D → VTK	✅	❌	❌

Note: Some metadata may be lost during conversion between formats with different capabilities.

Future Format Support¶

Need a format not listed here? Open a feature request on GitHub to let us know!

Planned additions:

HDF5 - Hierarchical data format
CGNS - CFD General Notation System

See the GitHub issues for feature requests and status.

Format Documentation¶

Tecplot: - Tecplot Data Format Guide - TecIO SDK Documentation

VTK: - VTK File Formats - VTK User's Guide

PLOT3D: - NASA PLOT3D Manual - PLOT3D User's Manual (PDF)