Creating a Surface and boundary from 3D Faces in Civil 3D

Autodesk Support

Mar 3, 2025

Products and versions covered

Issue:

How to create a surface from TIN triangles displayed as 3D faces and the boundary in Civil 3D.

Solution:

To create a surface from 3D Faces and a boundary outlining the 3D faces:

  1. Run the LINEWORKSHRINKWRAP command and select all 3D Faces from which the surface needs to be created. This will create a polyline around the future Surface.
  2. From the Home ribbon, Create Ground Data click Surfaces > Create Surface.
  3. In the "Create Surface" dialog, name the surface, select Style, rendering material, and click OK.
  4. In the Prospector tab, Expand Surfaces node, expand the surface (named in previous step) and expand Definition.
  5. Right-click on Drawing Objects, select all 3D Faces and check “Maintain edges from objects” and click OK.

     Add 3D objects to a Civil 3D surface 

  1. The program will create a Surface out of 3D Faces.

     Create surface from 3D faces  

  1. In the Prospector tab, expand surface’s Definition node, right-click on Boundaries and select Add. See: To Add Boundaries to a Surface.
  2. In the "Add Boundary" dialog, name the boundary and select a polyline created in step 1.
  3. This will create a boundary around the surface showing pretty close to what was on the 3D Faces.

     Added surface boundary 

Note:

For inner boundaries, a good practice is to create hatches. Then right mouse click the hatches and select "Create Hatch Boundary". Finally delete the hatch and review and correct the inner boundary polyline where needed.

 

 

Products:

Civil 3D;

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