Xrefs in Civil 3D

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In Civil 3D, attaching an external reference (xref) to a drawing

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inserts the entire contents of another drawing as a display-only object.

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Xrefs are versatile and easy to use for different file types,

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whether they contain a single object or a complete design.

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In this Civil 3D model, a surface has already been designed and built by the survey team.

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This is the existing ground surface, and when you look at it with the Object Viewer,

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you can see that the surface style changes according to the selected style.

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As a member of the design team, you are ready to start designing the roads,

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and you need the existing ground surface to start from.

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To keep the drawings light, you are going to use an external reference file.

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But first, since your other drawing was created in a specific coordinate system,

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you want to make sure that you set the same coordinate system in the new drawing.

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From the Quick Access Toolbar, click New to start a new drawing.

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In the Toolspace, on the Settings tab, right-click the drawing name and select Edit Drawing Settings.

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On the Units and Zone tab, set the coordinate system to match the project, and then click OK.

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Now, when you insert an external reference, the default coordinates are already set.

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If the External References dialog does not open, from the Insert tab, Reference panel, click Attach.

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From the Attach drop-down, select the type of reference file that you want to use.

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You can add a Bentley file, a DWF, a PDF image, a DWG, or many others.

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For this example, select Attach DWG.

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Select the file that your surveyor created, and then click Open.

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In the Attach External Reference dialog, you can set the Reference Type.

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Select Attachment to include reference files that were in the original, or Overlay to avoid circular references.

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For this example, select Overlay.

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Since you are using geographic data, there are no changes to make to the scale, insertion point, or rotation.

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Click OK.

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Once it is loaded, zoom to the extents of your file with the xref selected.

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In the toolbar, you can see that you are working with an external reference.

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From the Home tab, Layer panel, note that layer 0 is active.

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If you want to turn the external reference off, you can either turn off layer 0 or change its transparency.

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You can also right-click the reference and select Edit Xref in-place,

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which allows you to make changes to the original file.

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A benefit of using xrefs to reference objects is that Civil 3D can quickly read the surface data.

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For example, from the Annotate tab, Labels and Tables panel, expand Add Labels.

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From the Surface list, select Contour – Multiple.

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In the reference file, set a line across the desired contours to see that Civil 3D reads the surface data and adds the labels.