How can I make a perfect Subdiv dome shape with 12 vertices at the bottom?

Question

I am trying to make a perfect subdivision modifier dome shape (i.e. no surface distortion with subd enabled) that has 12 vertices at the bottom (i.e. where the dome connects to another shape I am modelling).

As you know the sphere given by blender doesn't work with subd, as the geometry at the top leads to distortions when combined with subdiv modifier.

Thats why I modelled a sphere using the following method (cube with subd that is adjusted with different method): https://www.youtube.com/watch?v=aRSVYFrRWeU

I only applied Subdiv lvl 1 and then cut the sphere in half. However that gives me 16 vertices at the bottom.

I need 12 (because the dome has to be connected to a shape that has only 12 vertices as connection points).

Is there a way to make a perfect subdiv dome with 12 vertices at the bottom?

Answer 1

You can create a first 32/16 vertex sphere, give it a Subdvision Surface modifier with a level of 4, rotate it 90° on y:

Make this first sphere invisible, create a second one that is a 12/8 (or 12/16 vertex depending on how many faces you tolerate), give it a Shrinkwrap modifier with the first sphere as Target, and a Subdivision Surface modifier, add some edge loops at the pole, move the edge loops until you don't see anymore bad shading, fill the pole with a ngon:

When you're glad, apply the Shrinkwrap: