Exporting Civil 3D Drawings

ByNeil Bondy

I was babysitting my nephews recently and astonished by their ability to fight over whatever toy the other one was currently playing with.  Sharing is clearly a learned behavior.  This got me thinking about file sharing and I started to realize how very little has changed in my adult life when it comes to sharing .DWG files.  Wouldn’t it be great if everybody played nice and we could share our toys without a big hassle?  Today I’m going to discuss practices and procedures for sharing Civil 3D drawings with other AutoCAD based applications using one of the following methods:

Object Enablers

Assuming the people you are working with are using the same release version, object enablers are the way to go.  You can download the object enablers here.  This will allow Civil 3D objects to show up as Civil 3D objects – a surface will be a surface, an alignment will be an alignment.  AutoCAD will still lack the ability to manipulate these objects because it does not have any tools to modify a surface or an alignment, but the objects will display as intended.  You can even explode them if you really need to make manual changes.  Note that you do not want to explode if you plan to ever use the file in Civil 3D again..

Proxy Graphics

Barring object enablers, proxy objects are another option.  On the Civil 3D side, you need to make sure the PROXYGRAPHICS variable is set to 1 when you save the drawing, otherwise the proxies will not be saved with the drawing.   On the AutoCAD side, you need to make sure the PROXYSHOW variable is set to 1.  Proxy graphics are not fool-proof.  For example, alignments and profiles currently do not show up for Civil 3D drawings saved in 2010 or 2011.  Another downside is that setting PROXYGRAPHICS to 1 increases the file size.

Automatically Exploding AECC Objects

If you are sending drawings to people using a prior release of AutoCAD, converting Civil 3D objects to AutoCAD primitives is really the only fool-proof option.  The Export to AutoCAD command (Menu Browser button->Export->AutoCAD DWG) is an easy way to do this.  If you need to convert multiple drawings/xrefs, use the ETRANSMIT command.  This converts the objects in the drawing, as well as in any xrefs, to AutoCAD primitives.

There are a few caveats to the Export to AutoCAD command and e-transmit.  AutoCAD does not understand the wonderful ability of Civil 3D labels to size themselves based on the drawing scale or viewport scale, nor the ability to rotate labels based on the VIEWTWIST angle.  The drawing will export with the current scale and Dview Twist angle set in model space, or your paperspace viewport, depending upon where you run the command from.  Thus, it helps make sure the model space drawing scale matches the viewport scale when you export it.

Here are some suggestions to make exporting smoother:

  • Avoid mixing scales within drawings.
  • Maintain a one layout per dwg setup and avoid multiple viewports with different scales on a single sheet.
  • Make sure the model space Dview Twist angle matches the viewport Dview Twist angle.

Occasionally, the above suggestions will be unachievable.  Then you might need to export multiple times at each scale/rotation adjusting settings accordingly.

Another problematic feature are the background masks on Civil 3D labels.  When these get exported, they become solid hatches with the true color of your background.  If your background is black they will plot as black, if you’re background is red, they will plot red.  To avoid this, you can either turn off the background mask in your Civil 3D label style before you export, or open the exported drawing, and erase them.  An easy way to erase them is to use the SELECTSIMILAR command, or alternatively, use QSELECT.

Manually Exploding Objects

The last option is to use the manual method, and simply explode Civil 3D objects.  If you go that route, make sure you explode labels before you explode the objects those labels reference.  While these conversion steps may not be ideal, performing them, checking the results, and communicating effectively with those you are working with will ensure that the drawings are exchanged effectively.

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