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I have prototyped a Python module to animate transformable nodes using vtkTransformInterpolator. I'm hoping to use it to create some nice animations for my projects and I thought it was a good idea to share it. It's probably not very useful now, but with some development by people who know better than me it might be usable in Slicer, specially within the Screen Capture module.
Please let me know what you think about this and feel free to propose and commit improvements.
I added some tests. Spline interpolation does not seem to work when rotations are included, and linear interpolation is not very smooth when multiples transforms are given. I think it would be interesting to apply the animations to multiple transformable nodes, with a list similar to the one in the "Apply" section of the Transforms module.