FACETDEV to Smooth Sectioned Civil 3D Pipe

Kevin Breslin

Richard Morrow | Application Expert

In this Blog I wanted to show you how to smooth your crossing pipes in profile and section views.

Within Autodesk Civil 3D, have you ever come across your pipes in section view and they look like octagons rather than the nice 12” RCP that you drew in plan view? If so, this is caused by the setting FACETDEV. 

The number you specify for facet deviation defines the maximum distance from the chord to the arc—the chord being an edge that is created from faceting the curve to the true mathematical arc. The facet deviation has a range of greater than zero (0) and no upper limit. The lower this variable is set; the more segments will be used to draw the pipe. The minimum number of segments is 8.

Pipe Appearance in Section View

Pipe sections are drawn using the FACETDEV (Facet Deviation) system variable. This variable controls the smoothness (tessellation) of curved edges of the pipes in section view.

The default value of FACETDEV will usually cause pipe sections to be displayed in section views with line segments, rather than as smooth curves. The following illustration shows an elliptical culvert in section view when FACETDEV is set to 0.5 feet.


If you set FACETDEV lower, to 0.01 for example, the appearance of the pipe sections will become more circular, as shown in the following illustration.


To change the FACETDEV variable

  1. At the command line, enter FACETDEV.
  2. At the Set New Facet Deviation prompt, enter 01. Adjust the value to a smaller number if greater smoothness is required.


  • The maximum number of facets is controlled by the FACETMAX variable. This variable can be set from 100 to 10,000. Note that using a small value for FACETDEV and a large value for FACETMAX will adversely affect drawing performance.
  • FACETDEV and FACETMAX are AutoCAD Civil 3D variables (rather than AutoCAD variables). They are therefore not listed when using the AutoCAD command SETVAR.
  • As with many other graphic-based settings/variables, using very high, or in this case, very low settings may negatively impact system performance.  Be sure to test the values with your system and your data.

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