Historically, if a user wanted to incorporate PDF data into a drawing, it had to be done using a reference, otherwise known as a “PDF Underlay”. Once attached, PDF underlays provide a great way to see the contents of a PDF file inside a CAD drawing. That being said, PDF underlays are essentially static, meaning you can’t make changes to the geometry or adjust display properties like lineweights or linetypes.
With the release of Civil 3D 2017, we have a powerful new tool that allows users to import PDF geometry as native AutoCAD entities. By importing PDF data, users have complete control over the display of the objects. In addition, if minor geometric changes are necessary, they can be done without redrawing an entire detail or exhibit. Generally speaking, this tool allows you to take full advantage of the geometry stored within the PDF file format.
If you are interested, I’ve created a quick video showing some ways to import PDF geometry into a Civil 3D drawing.
NOTE: PDFs are produced by many different applications having varying degrees of accuracy. Keep this in mind when incorporating PDF geometry into your designs. :)