Border smoothing in isotropic remeshing

[ipadjen]

Issue Details

The combination of NP relax_constraints(true) and a larger number of tangential smoothing iterations can cause unexpected results along the mesh border:

vs the same case but with relax_constraints(false)

To recreate the results from above, I used Polyhedron demo, nefertiti.off mesh and the following setup:

No feature edges were used.

Environment

• Operating system (Windows/Mac/Linux, 32/64 bits): Mac
• Compiler: Apple Clang
• Release or debug mode: Release
• Specific flags used (if any):
• CGAL version: master (2023-08-02)
• Boost version:
• Other libraries versions if used (Eigen, TBB, etc.): QT5

[janetournois]

Thanks @ipadjen for the report.
Did you experience that issue only in the demo or also in a standalone .cpp ?

[ipadjen]

I get the same behavior in a standalone .cpp when using the following NPs

CGAL::parameters::number_of_iterations(5)
                 .number_of_relaxation_steps(50)
                 .relax_constraints(true)

It is directly correlated to the number of relaxation steps, i.e. increasing it makes it worse.

[janetournois]

Thank you