Hi Jonathan,

it might be possible using Galapagos. Basically you need to come up with a metric that defines how well a certain section describes a circle. In the attached file I used a very simple definition, namely the output of the Circle Fit component that represents the largest deviation between the point-set and the circle.

It doesn't work perfectly, it has a slight tendency to 'find' good slicing planes near the ends of the brep, where the slice can yield a few nearly co-linear points. But you can limit the domain of the searcher by picking a shorter rail line segment (explained in the file).

--

David Rutten

david@mcneel.com

Poprad, Slovakia

god you are a true champ.

thanks david.

hi all, anyone able to understand this bit of mathematics enough to help us with an illustration using the figure attached earlier or otherwise able to guide us in GH? I think we only need it for the limited case such as the file attached but we are still struggling a bit with this one...

They appear as the intersections of the cyclide with spheres that are tangent to the cyclide in two points and which all pass through one fixed point. In the case that the ring cyclide is a ring torus, these doubly tangent spheres become doubly tangent planes. (I obtain the description for general ring cyclides from understanding the doubly tangent planes as spheres which all pass through the distinguished point at infinity).