How to create intermediate vertices of a humpy surface (interpolation) I took a cube, stretched it, added a number of intermediate edges and adjusted their height to get a humpy top surface.

Now, I want to get a smooth top surface by adding interpolated vertices. The existing edges must not change their position. How do I do this?

FYI: The object will be 3D-printed.
@eromod's hint was the solution.


I created a huge ovoid (an icosphere that I compressed on one axis for an additional hump on the other axis),
aligned it carefully manually,
extended the original top surface in top direction,
applied a boolean modifier with "Intersect" operation,
and did a bit afterwork on the mesh.


Please leave a comment if there's something I forgot to do proper preparation for rounded edges around the top surface.