You want to go virtual, not physical? It seems that the Geometry namespace version of surface is severly limited, as if it only supports a single triangle.
Geometry.Surface appears to be a base class for:
Geometry.ExternalSurface
Geometry.ExternalBoundedSurface
Geometry.NurbSurface
A lofted object would most closly relate to the nurb surface (a mere collection of points creating a surface.) Not a pretty sight. I would create the database lofted surface, and not make it database resident. (never add it to a block table record). I did something similar to this with polylines in order to get a 3D intersection point. The polylines defined the 'surface' for my intersection, the rest was done 'the hard way' because Autodesk did not supply me with an intersectWith method for my lofted surface and line. (GetPointAt in the loftted surface, would have been nice, but I guess a routine that can return a possible multiple points is too difficult for them right now)
There may be a was, as with other entities, to create the loftedsurface, and cast it into a geometry surface (of some type perhaps getgripoints - to nurb surface), but it doesn't stand out to me. I don't see a lot of programmers diving into AutoCAD's 3D engine. I did with VBA and it was painful.
Later,
jvj
