Obtain Envelope of two surfaces

Hi everyone,

I’m working on a problem that is driving me crazy! I have an initial cloud point that represents an existing tunnel. An ampliation of this structure is planned so a wider tunnel is modelled. I want to obtain the exterior surface of the combination of both surfaces but I am not capable…

I thought the easiest way to do that was to obtain closed brep from each surface and then join them. The problem is that one surface is a brep which easily I can achieve that but the cloud point is a mesh and I am not used to working with that.

Otherwise, I thought another method could be to represent the centroid of each face that composes the mesh and achieve the faces which are outside of the closed brep. The problem is that I am not able to combine both elements in one surface/mesh.

Anyone can help me?

Thank you so much!

Tunnel Problem.3dm (1.8 MB)