Create a spere

 From:  jki (JKISS56)
Surface creation in MOI
Task is simple, create a surface from 3 connected arcs, which should lead to a sphere shaped surface.
see from left to the right.

I used the “Network” function. the second shape is the result, one control point is totally asymmetrically placed. Why? Then I use symmetry to create a half sphere - an you can see sharp edges. Then I patched the original surface to make it symmetrical - and now the sphere is nice and smooth.

Now i tried to find the cause of asymetry. I added control points to arcs.

Now I see the asymetry
There is a difference in order how the curves are selected befor the network command is applied.

Another trial: using the sweep function:

Sweep is OK. It creates a symmetrical control point set, and the sphere is smooth. Unfortunately, it creates a huge amount of control points, making the surface practically un-editable

Quite near the victory I tried to use sweep for 3 free curves. And again: this does not work, system creates a strange artefact on top.

Back to my previous post: How to create a smooth surface, with minimum control points controlled by 3 different curves, assuming that the surface touching the curve has the same perpendicular as the curve in that point.