(Not directly about Rhino but may be of interest.)
Plasticity has introdiced a tool for going from a sub-division mesh to a smooth surface which they call “Polysplines”. The claimed primary advantages over Catmull-Clark subdivision such as Rhino SubD is G2 continuity at extraordinary points and smoother surfaces. https://www.youtube.com/watch?v=FFEIhpiBzb0&t=3s starting at 10:44
This appears to be the “Polyhedral-net Splines” method developed by Jorg Peters of the University of Florida Gainsville and others.
Presentation from 2024: https://www.youtube.com/watch?v=28DpLtrYnnk
Presentation slides: /https://geocomp2024.sciencesconf.org/data/TalkPeters.pdf
Polyhedral splines C++ package: Polyhedral-net Splines: Polyhedral-net Splines
Users manual: https://cise.ufl.edu/research/SurfLab/papers/23PolySpl_TOMS_Doc.pdf
License - research use: free and cite this article. commercial use: contact the first author.
Description of Peter’s work on polyhedral-net splines: Solid Modeling Association
Peters’ joint work with U. Reif (1000 citations) established the standard for the theory of subdivision surface algorithms. The fundamental analytic techniques were collected in the 2008 Springer monograph Subdivision Surfaces. The work shows that the limit of subdivision surfaces can only be understood through the differential geometry of a nested sequence of spline rings — and not naively as the refinement of a control net. The widely-used Catmull-Clark subdivision has shape-deficiencies and refines at a non-uniform speed near the extraordinary points. Peters’ latest joint work with K. Karciauskas on evolving guide subdivision generates “class A” high-quality subdivision surfaces at the same cost as the classical solutions. Moreover, guided subdivision algorithms offer more uniform refinement and have directly served as finite elements for engineering analysis.