Chapter 12: External References and Images

After completing this Chapter, you will be able to do the following: Working with External References Adding Dependent Symbols to the current drawing Controlling the Display of External References Editing External Files

One of the most powerful time-saving features of AutoCAD is the ability to have one drawing become part of a second drawing while maintaining the integrity and independence of the first one. When you drawing is attached as an xref, the referenced drawing is linked to the current drawing; any changes to the referenced drawing are displayed in the current drawing when it is opened. A drawing can be attached as an xref to multiple drawings at the same time. Conversely, multiple drawings can be attached as external references to a single drawing. This feature is provided by the XREF command, short for external reference. Why External References?

The symbols that are carried into a drawing by an external reference are called dependent symbols, because they depend on the external file, not on the current drawing, for their characteristics. The symbols have arbitrary names and include blocks, layers, linetypes, text styles, and dimension styles.

The XREF command provides various options for attaching and manipulating external references files from Xref Manager Xref Manager

AutoCAD displays Xref Manager palette.

Attaching External Reference – DWG, Image, DWF, DGN

External Reference Dialog box

Available options: Reference Type selection has two modes: Attachment mode -- the external references that are attached in this mode will be included in the drawing when the drawing itself is attached as an external reference to another drawing. Overlay mode -- the external references that are attached in this mode will not be included in the drawing when the drawing itself is attached as an external reference to another drawing. Retain Path selection determines whether or not the full path to the external reference is saved. Insertion Point, Scale, and Rotation selection are similar to insertion of a block.

Detaching External Reference Drawings Detach selection in the Xref Manager dialog box detaches selected external reference drawing(s) from the current drawing. If the external reference is currently being displayed as part of the current drawing, it disappears when you detach it.

Reloading External Reference Drawings Reload selection in the Xref Manager dialog box updates selected one or more external reference drawings attached to the current drawing. The Reload selection is provided to reload the external drawing when some one is editing the external drawing at the same time when it is attached to a drawing that is currently open.

Unloading External Reference Drawings Unload selection in the Xref Manager dialog box allows to unload one or more external reference drawings from the current drawing. Unlike the Detach option, the Unload option merely suppresses the display and regeneration of the external reference definition, to help current session editing and improve performance. This option is also useful when a series of external reference drawings needs to be viewed during a project on an as needed basis. Rather than having the referenced files displayed at all times, it can be reload when you require the information.

Binding External Reference Drawings Bind selection in the Xref Manager dialog box allows to make external reference drawing data a permanent part of the current drawing. AutoCAD displays the Bind Xrefs dialog box with two choices: Bind and Insert. Bind selection binds the external reference drawing as an ordinary block in the current drawing and it renames the dependent symbols and use them as you would use any other named objects. Insert selection binds the external reference drawing to the current drawing as if it is inserted in the current drawing just like inserting a drawing with the INSERT command.

Changing and Saving the path Browse selection in the Xref Manager dialog box displays Select New Path dialog box which allows to select different path or file name for the selected external reference file. Save Path selection in the Xref Manager dialog box saves the path of the currently selected external reference file.

XBIND command permanently adds selected subset of external reference-dependent symbols to the current drawing. The dependent symbols include the block, layer, linetype, dimension style, and text style. AutoCAD renames the dependent symbols that is added to the current drawing. Adding Dependent Symbols to the current drawing Xbind dialog box

The XCLIP command controls the display of unwanted information by clipping the external reference drawings and blocks. Clipping does not edit or change the external reference or block, it just prevents part of the object from being displayed. The defined clipping boundary can be visible or hidden. Controlling the Display of External References

Options include: New selection (default) defines a rectangular or polygonal clip boundary or generates a polygonal clipping boundary from a polyline. ON/OFF selections controls the display of the clipped boundary. Clip depth selection sets the front and back clipping planes. Delete selection removes the clipping boundary for the selected external reference or block.

REFEDIT command edits block references and external references while working in a drawing session. This is referred to as in-place reference editing. If you select a reference for editing which has attached xrefs or block definitions, the nested references and the reference are displayed and available for selection in the Reference Edit dialog box. You can also display the attribute definitions for editing if the block reference contains attributes. Modify menuChoose In-Place Xref and Block Edit > Edit Reference On-screen promptrefedit (ENTER) Editing External Files

Edit Reference dialog box

Objects selected that belong to any nested references cause all the references to become candidates for editing. The objects chosen are temporarily extracted for modification in the current drawing and become part of working set. The working set objects stand out so they can be distinguished from other objects. All other objects not selected appear faded. You can now perform modifications on the working set objects. When a reference is being edited, the Refedit toolbar is displayed. You can add and remove working set objects and save and discard the changes.