Boundary line of a flat object


I am thinking how to find the boundary line of a flat object that includes splines, semicircle and lines.
It could be easy in case of a polygonal object by selecting grips but for curves I have no idea.

I can also evaluate the curves and simplify it by some points on the curve and then connect it but there might other way.

Can anybody suggest how to do it?

Can you give an example of the geometry?

And what tools are you hoping to use to extract the boundary? e.g. PythonScript, RhinoCommon Plugin, Grasshopper?

Thanks, it is like in the picture. This will be the duplicate surfaceBorder

Cool, this script should help get you started.

This is a python script, but you could translate the principles to a RhinoCommon plugin if needs. Let me know if you need help modifying it to fit your use case.

Thank you Tom. The method works just fine.