After a lot of trial and error I seem to be making some progress importing the 3D models of various engineering disciplines into my Revit Landscape/Urban Design model in a workable format at the correct location. Here's my workflow (which I reserve the right to modify as I continue to sort this all out
) Doing it in this manner allows you to acquire levels and snap to edges of the imported geometry within Revit.
Step 1: Obtain a top-level surface mesh in 3D dwg format
Get your engineer or drafting guy to provide the top surface of the road/infrastructure/etc. model as a mesh or .TIN in 3D dwg format. They should know how to do this. You can't do it as a landscape architect because you don't know engineering software like openroads, microstation, etc. It's crucial to get only the top-level surface as a mesh, e.g. the 'surface' of the road and not sides and bottom of a road volume. If you get more than this you will have problems in the next step.
Step 2: Reduce the mesh and convert to Nurbs
Open a clean Rhino file with the same units as the engineering model (i.e. meters). Run an Import command to bring in the 3Ddwg mesh. Create a point in the Rhino file at the same coordinates as your Revit file's project base point. Use this newly created point to move the mesh in your Rhino file to 0,0,0. Then select the mesh and run a ReduceMesh command (for me reducing to no more than 10k polygons works well). Now select the reduced mesh and run a MeshToNurbs command, which will create an open polysurface. Delete everything in the model except the open polysurface. Run a Purge command. Save the Rhino file.
Step 3: Import Rhino into Revit and save as a Revit file
Create a new file in Revit using a default template. Use the official Revit plugin "Rhino.Inside" to import the Rhino file into Revit (https://www.rhino3d.com/inside
). Save as a Revit file.
Step 4: Insert into your Revit landscape model
Open your Revit landscape model and run an Insert command. Choose positioning method: Auto - Origin to Origin.
You're done. Have a beer.