How to make surface like this picture?

[laurent_delrieu]

Hello
nothing very hard, it is the use of a tool like Dendro. If you use Rhino 8 you could take Shrinkwrap.

Dendro

Rhino 8 Feature: ShrinkWrap

ShrinkWrap lets you create a wrapped mesh from mesh, NURBS geometry, SubD, and Point Clouds. Just about anything! ShrinkWrap meshes are ideal for creating: Meshes for 3D printing. A solid union mesh from multiple input objects. A solid mesh from 3D scan data fragments. Meshes without internal self intersections. Offset meshes for shell operations Reverse engineering workflows Point cloud meshes Valid closed meshes from broken or often hard to repair geometry. [0648] [ShrinkWrap] …

Here is an example using some hidden component of Nautilus
Here with a step of Pi/2

And a step of Pi/4 (like in your example)

field stepped Nautilus.gh (12.3 KB)

I aslo have other fields