Create a toposurface from a DWG file.
This video demonstrates the following:
In Revit you can create a toposurface from a DWG file.
The DWG file is linked or imported into your Revit model. In either case, after the toposurface is created, the DWG file is no longer needed and can be removed from the model. In this example, the DWG is linked. In the dialog, make sure that the Current View Only option is not selected. This will allow the DWG file to be linked as a 3D object that includes the contour information you need to create a toposurface. Select the other import settings as desired.
Switching to a 3D view, you can see that each of the contour lines in the DWG file has a Z position. If all the geometry in the DWG is flat, then it cannot be used to generate a toposurface.
On the Massing and Site tab, select the Toposurface tool. Then, on the Edit Surface tab, open the Create from Import drop-down, and click "Select Import Instance." In the drawing area, select the imported DWG instance.
In the dialog, you select the DWG file layers that contain contour information. Elements on these layers will be used to generate elevation points for the toposurface. Information on the unselected layers will be ignored.
Points are generated based on the DWG geometry. You can modify the generated points or add points to the toposurface if required. Click Finish to complete the toposurface.
If no other information is needed from the DWG file, it can be removed from the Revit project.
In addition to using a DWG file to create a toposurface, you can manually place elevation points, or import a point's file generated by a civil engineering software application.