Creating a Surface from 3D Faces or 3D Lines in Civil 3D

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We have all probably received a drawing at one time or another that contains 3D faces representing a surface.  Now your job is to convert these 3D faces into a Civil 3D surface that you can use for creating Profiles, Sections, Contours, and a variety of other things. The best way to translate a surface from one software package to another is to use the LandXML import/export format. This will allow you to import an exact copy of the original surface without recreating it from 3D faces or 3D lines representing the TIN. This is the fastest way to get a surface that was created in another program into Civil 3D and it also eliminates the possibility of errors being introduced during the process of rebuilding the surface. However, the person supplying you with the drawing may be unable, or unwilling, to export the surface as a LandXML file for you. If this is the case Civil 3D has tools that make creating a surface from 3D faces or 3D lines representing a TIN both accurate and easy.

  1. On the Prospector tab of the Toolspace, right-click on Surfaces and select >> Create Surface.

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  1. Confirm that TIN surface is selected as Type.
  2. Select the desired Surface layer and Style.
  3. Click <<OK>> to close the Create Surface dialog box.
  4. On the Prospector tab of the Toolspace, expand the Surfaces node.
  5. Expand the Surface Name.
  6. Expand the Definition node under Surface Name.
  7. Right-click on Drawing Objects under the Definition node and select >> Add.

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  1. Set the Object type to 3D Faces.
If your drawing contains 3D Lines representing the TIN instead of 3D faces select Lines from the list.
  1. Enable the option to Maintain edges from objects.
This option will create the new surface with triangles that match the exact geometry of the selected TIN lines, rather than just sampling the endpoints of the selected TIN lines and re-triangulating by proximity. This is similar to treating all of the selected TIN lines as breaklines.
  1. Click <<OK>>.
  2. Select all the 3D Faces with a crossing window, then [Enter] to end the command.
The new surface will be built from the selected TIN lines and displayed according to the style that you assigned earlier.

2 Responses to “Creating a Surface from 3D Faces or 3D Lines in Civil 3D”

  1. It all worked fine, but Civil has extended the surface and lost the original boundary. How can stop Civil to add triangles to the one I already have?

    • You will need to add a boundary to the surface, or you can go to the Surface Properties and set the Maximum Triangle Length, or the Maximum Angle Between Adjacent TIN Lines option. Either of these would address your issue.

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