UV mesh of trimmed surface strange behavior

I have a trimmed flat surface (UV_mesh.jpeg) meshed in Grasshopper using UV mesh.

When I deform the surface and mesh it again, I obtain a mesh that goes beyond the boundaries of the surface. (strange mesh.jpeg)

What can be the reason for that?

Thanks in advance!

UV’s are part of the full surface, not the trimmed surface. A nurbs surface is made up of a UV grid, when you trim a surface you do not trim this UV structure, it is just hidden.

Thanks a lot for the reply!
I understand your point that the UV mesh is built on the untrimmed surface.
But how did the mesh in the first picture occured???

If it is the case, i would suppose that also in undeformed geometry, the UV mesh would extend beyond the surface.
Is it true?

Dunno. You don’t have a file attached and your screenshot doesn’t show mesh wires so it is hard to tell.

all the green + are mesh nodes! NOT control points.
Do i need to send a pic with the Cps?

Attach file

I cannot attach files due to sensitivity reasons.

Initial trimmed geometry with 15 Cps

10x10 UV mesh of this geometry

10x10 UV mesh of the deformed geometry

Could you state if the difference in the 2 cases is reasonable.
(In the initial geometry the mesh does not go beyond surface
In the updated geometry the mesh goes beyond surface)

If it is impossible to help me further without files, it is understandable.