Creating Sail Vault in Rhino

Hello Rhino professionals!

I’m writing here hoping to resolve the following task:
I have three curves of three arches which have different width and height, and need to make a half sail vault out of them (see images attached).
I tried patch tool, edgesrf tool, networksrf tool, but none give me a good architecturally smooth result.
Unfortunately I am absolutely not familiar with SubD, so I can’t apply this tool to my case…

I would like to ask your advice on how to make the vault. Any hint is appreciated.

Thank you!

Hi @couningen,

It would be easier to offer advice if you had posted your model so we could work with your actual curves.

But assuming the three arcs you have drawn are semi-circular, you can:

  1. Draw a diagonal line through the bottom points of the large arc.
  2. Draw a sphere centred on the mid point of the new line and with the radius of the large arc.
  3. In the Front viewport, use the new line to Trim the sphere, removing the unwanted bottom half.
  4. In the Top viewport, use the diagonal line to Trim the hemisphere, removing the open side opposite the two arches.
  5. In the Front viewport, use the rear arc to Trim the partial hemisphere, making the opening.
  6. In the Right viewport, use the side arc to Trim the partial hemisphere, making the second opening.

Giving you:

This is just one way to create the vault. There are others (e.g. you can use a right triangle in the top view to trim the sphere instead of creating the two side arcs).


Did you try EdgeSurf? (aka surface from edge curves)

SAIL VAULT.3dm (115.9 KB)
sail vault

Dear Jeremy,

Thank you for your suggestion.
I tried to follow your method, but couldn’t obtain a proper result… I don’t know why :frowning: (
I am sending the file with three vaults; by now I keep on struggling without much of success.

Halfsail_vault_issue.3dm (134.1 KB)

Hi @couningen,

A Sail Vault is basically a hemisphere with openings that are semi-circular in section. The semi-circles must have a radius less than the radius of the hemisphere in order to cut through it. Your shapes do not conform to these constraints. In particular one of the side arches is taller than the central arch. If this is deliberate, we need to find a different name for your structure!


Here is a vault using your curves with @dmoyes edge-based surface recommendation. Note that I rebuilt your three curve so each would have 20 points before creating the surface. Balance helps with this type of surface.

Halfsail_vault_Edge_Based.3dm (271.2 KB)


Dear Jeremy,

Thank you very much for your contribution.
I was actually trying to build such “whatever it is called” vault with EdgeSrf :smiley:
The result was similar to yours, but in the final model where this vault it observed from below it doesn’t look realistic.
I actually have the real reference which I am supposed to model (see photo) and which I visited, and the uppermost point of this pseudo vault is lower than how it comes out with EdgeSrf.

Anyways I will keep on trying :slight_smile:

It looks to me like the two arches likely have the same arc but the taller one sits higher and is extended by straight ‘legs’ to the common base.


Ah, that’s really helpful. I originally interpreted your diagonal curve as the vault profile, then as an opening on the vault surface. But from the photo it appears to relate to an arch below the vault surface which makes much more sense.

I think you may have some photo interpretation issues. But to understand that it it necessary to know if the photo shows true perspective or has been manipulated to counter the appearance of perspective (either by being taken from a rising front camera, clipped from the periphery of a very wide angle lens, or post-processed in, say, photoshop). What can you tell us about that?

And do you have any other resources relating to this, such as a floor plan, or more photos from different angles? How does the vault ceiling interface with the hidden side of the front arch?