# Paraview unable to read lagrangian data (openFoam)

**URL:** https://discourse.paraview.org/t/paraview-unable-to-read-lagrangian-data-openfoam/3456
**Category:** ParaView Support
**Created:** [January 30, 2020, 3:42am UTC](https://discourse.paraview.org/t/paraview-unable-to-read-lagrangian-data-openfoam/3456 "2020-01-30T03:42:00Z")
**Posts on this page:** 1
**Showing post:** 8

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### Author: ![olesenm](https://discourse.paraview.org/user_avatar/discourse.paraview.org/olesenm/32/17416_2.png) [@olesenm](https://discourse.paraview.org/u/olesenm)
#### Post date: [March 12, 2020, 11:32am UTC](https://discourse.paraview.org/t/paraview-unable-to-read-lagrangian-data-openfoam/3456/8 "2020-03-12T11:32:12Z")

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@mwestphal Additionally we may wish to have a _sticky_ FAQ (for the OpenFOAM question).

The problem (and confusion) originates from an internal OpenFOAM change to use barycentric coordinates in its lagrangian framework.

In the [openfoam.com](http://openfoam.com) version:

- The `positions` file contains tuples of (x,y,z, cellId). This file is generally ignored by OpenFOAM (in favour of the `coordinates` file), but is readable by ParaView. The format is consistent with what older versions of OpenFOAM generated.
- The `coordinates` file contains the barycentric coordinates. This is used for OpenFOAM restarts but not by ParaView.

In the [openfoam.org](http://openfoam.org) version:

- The `positions` file was changed to contain the barycentric coordinates (identical contents to the [openfoam.com](http://openfoam.com) `coordinates` file). Cannot be read by ParaView.

It is probably not realistic to expect support for the [openfoam.org](http://openfoam.org) `positions` file. This would require shadowing the volume mesh in order to define the cells, additional tet decomposition of the volume cells, additional barycentric calculations to determine the corresponding x,y,z positions.

Available options, in any order of preference:

- use the [openfoam.com](http://openfoam.com) version that generates a `positions` file that can be read by ParaView.
- use foamToVTK or foamToEnsight to convert the lagrangian fields only.

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_[View the full topic](https://discourse.paraview.org/t/paraview-unable-to-read-lagrangian-data-openfoam/3456)._