Civil 3D surface to Rhino single surface by grasshopper

Hi guys, I am sorry I am a beginner.
I have a Civil 3D surface (extracted 3D solid) from my colleague. How can I create an exactly the same (at least very very similar) surface in Rhino by grasshopper? Thank you very much!!!

11NEDC447-CSH-ECM-SI-SVYMAP.dwg (5.6 MB)

Convert Mesh to (13.6 KB)

I tried the above. It can form a single surface but I need a surface with higher accuracy. Is is possible?

Hi -

You are using a plug-in so I can’t tell what surface you generated in your definition.
That said,

You will never be able to create a single NURBS surface from input like this.
Why do you need a single surface?

Hi wim,

My colleague wrote some script by grasshopper to distribute different objects on the surface but everything start with a single surface.

The staircases and u-channels can be ignored

Hi -

I would think that pre-processing that input geometry would take a lot more work than trying to modify the Grasshopper script so that it can take a polysurface or mesh as input. Without more information, that’s hard to be sure of, though.