Filtering a Point Cloud for Surface Data in Civil 3D

In two previous videos I explained the process of importing a LiDAR point cloud into Recap and processing it out as an RCP or an RCS file for use in Civil 3D.  Then I explained how to import that RCP or RCS file into Civil 3D.  If you have not yet seen those videos you can find them here:  Point Cloud to Recap to Civil 3D Workflow. 

Now that we have the data in Civil 3D we need to generate a surface representing the existing ground conditions.  The problem we have though is that the point cloud imports everything that is scanned. This means I will get contours representing tops of trees, power poles, signs, fire hydrants, vehicles, etc.   I only need to show a surface which contains ground shots.  In this video I explain the process of filtering out just the ground data and then creating a surface from that data: 

https://www.google.com/search?q=filtering+a+point+cloud+for+surface&rlz=1C1GCEA_enUS1015US1015&oq=filtering+a+point+cloud+for+surface&gs_lcrp=EgZjaHJvbWUyBggAEEUYOTIGCAEQRRg8MgYIAhBFGDzSAQkxMjc4OWowajeoAgCwAgA&sourceid=chrome&ie=UTF-8#fpstate=ive&vld=cid:62265237,vid:c5pB1rU3Erk