​Where is “Relax Polygons” in the latest Slicer version? Any alternatives?

Support
1

​Hi everyone,

I’m using the latest version of 3D Slicer (version 5.6.2), and I can’t seem to find the “Relax Polygons” option in the “Surface Toolbox” module anymore.

In previous versions, I used “Relax Polygons” regularly to smooth mesh surfaces (such as STL models) before computing curvature using `vtkCurvatures`. This helped reduce curvature calculation errors caused by rough or noisy geometry.

However, in the latest version, Surface Toolbox is still available, but the “Relax Polygons” feature seems to be missing.

Questions:

1.Was “Relax Polygons” removed or renamed in recent versions?

2. Is there another module that includes this functionality?

3. If it’s no longer available in the Graphical User Interface, is there an equivalent method—such as a Python script or another module—to perform the same Laplacian smoothing?

Any advice or workarounds would be greatly appreciated. I rely on this feature for preparing surface models for curvature and morphometric analysis.

Thanks a lot!

2

1.Was “Relax Polygons” removed or renamed in recent versions?

Hi, yes. Here is the code:

3

It appears to have been removed through the following PR by @lassoan , where he mentions:

removed relax option (it was the same as smoothing).

4

Thanks for sharing the code! I tried to use it but I’m not sure how to make it work in Slicer. Could you please provide some guidance?

5

Thanks for sharing the code! I see this is a C++ implementation. Could you guide me on how to implement this in Slicer? Should I compile it as a standalone module, or is there a way to achieve the same smoothing effect using Python and VTK within Slicer’s environment?

6

The C++ code looks like just some parameter settings on vtkWindowedSincPolyDataFilter so it should be basically trivial to make a python version. If it does something better than what you can do with the smoothing option, you can look at what parameters matter and maybe just expose them in the smoothing option UI.