Solid 3D: Area Below Surface TIN

Hi,
could you please help me?
I have done script which calculate solid area, which is calculated only below surface TIN.
It works only when solid 3D is small and within only one surface triangle. DWG and Dynamo script is attached.






D4C3D_Solid3D_AreaBelowSurfaceTIN.dwg (2.1 MB)
D4C3D_Solid3D_AreaBelowSurfaceTIN_01.dyn (42.3 KB)

Why not just take the area of the bottom face of the solid?

Because I need also area of other faces but reduced to area which appears below TIN surface.

It seem like the Surface.Thicken node was the root of the problem. The polysurface of the intersection area was too close together making the solid difference node fail. If you use the entire surface that’s wider than the solid and thicken that surface, it seems to work better.

Also, you can change the input of the Surface.Thicken node to thicken at a larger amount that will create a solid higher than the selected solid. By doing this, the Solid.Difference node will remove the entire portion of the solid above the surface leaving only the solid below the surface. See attached.
D4C3D_Solid3D_AreaBelowSurfaceTIN_01.dyn (30.8 KB)