How to find the transformation matrix of family symbol profile in selected-path Sweep/SweptBlend by using RevitAPI ?

[myownroc]

I've created a swept blend, which is from a circle to a hexagon with a circle arc path.

Then I've created a sweep with a selected path (see the blue line in part 1 and the result shows as part 2) and a loaded profile (see picture part 3). (That means Path3d is not null in sweep and ProfileSymbol is not null in sweep.)

It is obvious that the profile has been transformed before creating sweep. The profile has been rotated and moved.

How to find the transformation matrix (Autodesk.Revit.DB.Transform) ? I didn't find it.

[longt61]

Basically, the profile should stay on the sketch plane of the start point or end point or the blend, depending on whether it is bottom or top profile. If you draw you profile, it is quite easy to get the transformation based on its sketch plane (origin, Xvec, Yvec, normal); but if you use a loaded profile, it is quite difficult to do so because of the missing sketch plane.