Automatically generate a toposurface based on 3D contour data imported from DWG, DXF, or DGN files. 
 
  Revit analyzes the data and places a series of elevation points along the contour lines. 
When importing contour data, follow these requirements:
- The imported CAD file must contain 3D information.
  
- In the CAD file to import, each contour line must be positioned at the correct "Z" value.
  
- When importing the CAD file into 
	 Revit, do not select the "Current View Only" option.
  
 
  Video: Create a Toposurface 
    
To create a toposurface by importing contour data
- Open a 3D view. 
  
- Click Massing & Site tab Model Site panel Model Site panel  (Toposurface). (Toposurface).
- On the Modify | Edit Surface tab, click Tools panel Create From Import drop-down Create From Import drop-down  (Select Import Instance). (Select Import Instance).
- Select the imported 3D contour data in the drawing area. 
	 The Add Points from Selected Layers dialog displays. 
	  
- Select the layers to which you want to apply elevation points, and click OK. 
  
Note: To improve system performance related to surfaces with a large number of points, 
  
simplify the surface.