Thursday, May 7, 2015

Adding Breaklines to a Civil 3D Surface

I see a number of Civil 3D users adding a surface smoothing edit to smooth contours. Surface smoothing often creates a very large TIN Surface (Triangulated Irregular Network) and CAD file. A construction contractor may also have a difficult time working with a large TIN and CAD file if used for Machine Control. Breaklines can be added to a surface to create a cleaner TIN and contour lines.

Here are the steps:
Once the breaklines have been modeled and are ready to be added to a surface, adjust the Supplementing Factors in the Add Breaklines dialog box. The following settings work well but adjust them as needed.

• Turn on and set the Distance to 10.00’.
• Set the Mid-ordinate Distance to 0.01’.

Below are the links explaining the Supplementing Factor Distance and Mid-ordinate Distance from Autodesk’s Help file.

Autodesk Civil 3D Help: Supplementing Factors

Autodesk Civil 3D Help: Mid-ordinate Distance

Below are images of a surface with the default settings.

Below are images of a surface with the adjusted settings. Additional editing may need to be added to smooth the contours.

Let me know if you have any questions. 

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