Importing obj files containing NURBS does not recreate the curve which was exported #85649

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Christine · 2021-02-15T12:31:59+01:00

Christine commented

2021-02-15 12:31:59 +01:00

System Information
Operating system: windows 10 pro
Graphics card: nvidia 2080 super

Blender Version
Broken: 2.83, 2.91.2

Addon Information
Name: Wavefront OBJ format (3, 8, 1)
Author: Campbell Barton, Bastien Montagne

Short description of error
In an obj file exported from Blender, NURB curves are lost.

Exact steps for others to reproduce the error

In a fresh scene, add a nurbs curve.
Select it
export it as obj.
Delete the cruve.
Import that obj.
The parameterization is lost.

**System Information** Operating system: windows 10 pro Graphics card: nvidia 2080 super **Blender Version** Broken: 2.83, 2.91.2 **Addon Information** Name: Wavefront OBJ format (3, 8, 1) Author: Campbell Barton, Bastien Montagne **Short description of error** In an obj file exported from Blender, NURB curves are lost. **Exact steps for others to reproduce the error** - In a fresh scene, add a nurbs curve. - Select it - export it as obj. - Delete the cruve. - Import that obj. The parameterization is lost.

Christine commented

2021-02-15 12:31:59 +01:00

Added subscriber: @cmk_blender

Thomas Trocha commented

2021-02-15 17:34:38 +01:00

Added subscriber: @dertom

Thomas Trocha commented

2021-02-15 17:34:38 +01:00

When exporting to obj your nurbs curve is applied to 'mesh' and only vertice- and edge-informations are saved to the obj-file.
Loading importing this obj again will only restore this data which will result in a mesh.
Obj ist not suited to save paramaterisation. The only format that will preserve this data is (afaik) a blend-file.

When exporting to obj your nurbs curve is applied to 'mesh' and only vertice- and edge-informations are saved to the obj-file. Loading importing this obj again will only restore this data which will result in a mesh. Obj ist not suited to save paramaterisation. The only format that will preserve this data is (afaik) a blend-file.

Germano Cavalcante commented

2021-02-15 20:54:28 +01:00

Added subscriber: @mano-wii

Germano Cavalcante commented

2021-02-15 20:54:28 +01:00

*.obj format has support to Free-form Surfaces that could be a response to Blender's curves.
But I fear that this has never been implemented in the Blender exporter.

*.obj format has support to [Free-form Surfaces ](https://docs.fileformat.com/3d/obj/#:~:text=its%20print%20quality.-,Free%2Dform%20Curve,best%20defined%20by%20freeform%20curves.) that could be a response to Blender's curves. But I fear that this has never been implemented in the Blender exporter.

Christine commented

2021-02-16 03:16:51 +01:00

The FBX format does support NURBS, although not in the blender importer/exporter plugin.