Export a points file from a civil engineering application, and import it to create a toposurface in the Revit model.
The points file provides contour data using a regularized grid of elevation points.

The imported points file must adhere to these requirements:
Additional information in the file (such as a point name) is ignored. If the file contains 2 points with the same x and y coordinates, Revit uses the point with the largest z value.
Click to download sample points file.
To create a toposurface with a points file
 Model Site panel
Model Site panel
 (Toposurface).
 (Toposurface). 
   Tools panel
Tools panel Create From Import drop-down
Create From Import drop-down
 (Specify Points File).
 (Specify Points File). 
  Revit generates points and a toposurface from the coordinate information in the file.