Topography, sub-regions and building pads

Dear Maxime, welcome to the forum. I am not a Dynamo expert, so I can only address the pure Revit API side of things:

Q: generate toposurface:

A quote from the latter: “Developing this application is only possible in Revit 2014 (and later) in which the API library includes constructors for SiteSubRegion and BuildingPadType.”

Q: create building pad:

Yes:

Q: create subregion

Yes:

Q: create masking element?

This I don’t know, cf.:

I would suggest asking and discussing this last question in the Revit API discussion forum, continuing that thread.

Cheers,

Jeremy