Exporting in VTK format

In this section, we will explain how to export a 3D object in a VTK format file.

How to use it

Put :

into a node where a BaseMeshTopology exists.

• filename = : where to save exported VTK file
• edges/triangles/quads/tetras/hexas= : which primitive you want to export (at least one type is required)
• pointsDataFields= where string= : indicates where the exporter will get its values to put on the points. Obviously, the number of values has to be the same as the number of points. Several data can be listed, just separate them with a space.
• cellsDataFields= where string= : the same as the points. You must notice that, for now, the mapping between a primitive and a value is not possible. Consequently, only one primitive can get values (as the number of values must equal the number of cells)

Limitations

For now, this class supports only , for the data, Vec{1,2}{f/d} as an array of values and Vec3{f/d} as an array of vectors (‘real’ vector with arrow and so on …) The export is processed when Control+E keys are pressed.Don’t forget to set listening to true.

Example

• example/Component/Collision/Response/VTKExporter.scn

Reconstruct VTK mesh in ParaView

The VTKExporter component will export the mesh as a “VTK Unstructured Grid”. This part will explain how to get back a “VTK Polygonal Mesh” which could be reload in SOFA. This pipeline has been realised using ParaView release 3.6.2.

• Step 1: Open your export file: example.vtk0.vtu (File -> Open).
• Step 2: unselect “position” and then apply.
• Step 3: Extract Surface (Filters-> Extract Surface), and apply.
• Step 4: Save Data as VTK file, either in ascii or binary (File -> Save Data).

You can now use the component MeshVTKLoader to load this mesh in SOFA. Additionally, if you want to save only the principal component of the mesh (remove small elements) Between step 2 and 3 do:

• Step 2.1: Filter -> Connectivity, and apply.
• Step 2.2: Filter -> Threshold, and change the boundary to keep region between 0 and 1