Anyone who spends any time with Civil 3D, especially those who work with feature lines, will undoubtedly come across arcs with an excessive number of vertices. This is typically due to converting feature lines or 2D Polylines into 3D Polylines which do not support true arcs, thus converting them into line segments.
As an example, I frequently receive Civil 3D drawings from clients where all the Feature Lines have been exploded down to basic AutoCAD objects, a commonly used option while eTransmitting drawing files. What is left is a drawing with 3D Polylines filled with vertices, among other things. Cleaning up such a drawing could be very time consuming if you opt to trace each curve or ask the client for a new file.
To quickly clean these vertices up, we first need to convert the 3D Polyline to either a Feature line or 2D Polyline, object types which supports true arcs.
Converting to a Feature line is done using the “Create Feature Lines from Object” (AeccCreateFeatureLines) command found on the Home tab>Create Design panel>Feature Line drop-down.
Converting to a 2D Polyline is done using the “Convert 3D to 2D Polylines” (AeccConvert3dPolys) command found on the Modify tab, Design panel drop-down.
After converting the 3D Polyline to an object that can support curves rather than line segments, we can proceed to clean up our curves. To do so, we are going to use the “Fit Curve” (AeccFitCurveFeature) command found on the Modify tab>Edit Geometry panel. This command is intended for Civil 3D Feature Lines, but like many other edit geometry tools, this tool can be used on 2D Polylines as well.
Once executed, cleaning up curves is just a matter of hovering over the curve to be cleaned to preview the curve then click. Civil 3D intelligently figures out the radius intended and creates the arc, eliminating all those unwanted line segments and vertices.
Some curves are not quite as easy for Civil 3D to figure out, which becomes apparent while previewing its proposed curve. In these instances, use the Points option as indicated by the command line options while the command is active. Doing so prompts you for the start and end points of the curve and will fit a curve through these start and end points.
This command also has some options related to it by typing in “O” for Options after executing the command and selecting the intended object to be modified. These options give you the chance to change the tolerance, which specifies the maximum distance from a PI along the feature to the arc that is to be inserted, and minimum number of segments, which specifies the minimum number of segments that must be identified before creating an arc. This setting is ignored when the Points option is used.
As you can see, cleaning up curves which have excessive line segments and vertices is not as labor intensive as it normally would be when not using the “Fit Curve” (AeccFitCurveFeature) command. Knowing that various tools that were created for Civil 3D objects also work on some basic AutoCAD object types opens up some new workflows that may otherwise be a real chore.
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