Arc between 3 curves

I have 3 curves here and i try to make arcs through them like the UWE pavilion. Any idea of how to do it?

This is the pavilion


It seems to be simple. 3 curves from there a pavilion. Before moving into recreating this, here I have attached some useful links which helps you understand about the pavilion how it was evolved and the process behind it etc…

Importantly, more than me @johnharding is the right person to give more insights about this.


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Hi @kanni914,

Firstly thank you @ajarindia for providing links to the paper, the Karamba article and for including me in the thread.

  • The first thing to mention about the pavilion is the symmetry. There are actually only 15 unique curves, with mirror symmetry and 3-fold rotational symmetry. This made fabrication and construction much easier than it could have been.
  • From the base curves a surface was generated to fit the constraints of the site, we had limits such as height and a surrounding rare flower bed that needed to be accommodated. Note that minimum lath bending radius was also important during the design phase, indeed the smaller the pavilion got the more this became the overriding constraint.
  • From this surface, we generated geodesic curves. This is important because the timber laths could be unrolled straight, negating the need for any CNC machining. For a good reference on this, see here:
  • Now, the usual geodesic component that comes with Grasshopper uses two points as an input. This might be ok for your purposes and indeed I think we made some lacing parts this way, however we wanted to make sure most of the geodesics always went up vertically from an initial point. We had to write a script to generate these (based on the plank lines paper above) which gives a geodesic from a starting point, initial direction vector and boundary curve to end. The script actually takes two surfaces, in case you have a mirror one where the lath will continue onto.

I’ve attached the script from the pavilion to generate the geodesics, I don’t mind sharing it. It should allow you to generate curves from your starting points, given that you make the guide surface of course. Points on the starting curve (a) leads to end curve (b). The parameters control aspects such as number of iterations, and length of steps as the geodesic curve is generated. (22.2 KB)

Hope that helps, any more questions please feel free to ask. Good luck with it - symmetry should be your friend if you want to recreate something like this $:)

Best wishes,



& This is roughly how the final model was made:

  1. Create some arcs and curves using 120 degree symmetry. The small fillet in the middle should be a blend curve with nice continuity of curvature. The surface is symmetric about the middle. Different arcs will mean different shapes of course.
  2. Use NetworkSrf, the quality of the surface is dependent on how the curve above are made.
  3. Rotate copy 120 degrees.
  4. Use the script above to create geodesic lines. You will need to choose two out of the three surfaces and the starting points.
  5. Mirror and rotate copy these curves. The layout is highly dependent on the shape, something that took much time to grapple with.

It’s not an ideal method, a bit of a fudge if I’m honest due to time constraints. If I were to do it again I would probably use meshes instead.