Working effectively with CAD plans Part 2 - Attach Xrefs

In the first part of this series, we talked about how to merge DWG drawings intro your Archicad project.

There's two options:

1. Merge content of AutoCAD model space intro the current view of Archicad.
2. Append AutoCAD papers space (s) to layout book in Archicad.

The second way to import a CAD drawing in Archicad is to attach it as an external reference.

External reference files (XREF) are similar to Hotlink Modules, the difference is that they are DXF or DWG files and not ARCHICAD files.

This method allows you to save disk space. By attaching a DWG or DXF file to your Floor Plan, the file is loaded and displayed in the Project.

To attach an Xref to the current ARCHICAD Project,?use:

File > External Content > Attach Xref

When the Attach Xref dialog box is displayed, browse for a DWG file in your disk or from the BIMcloud.

Attach Xref options

The following options are set the same way as for merging a DWG file (part 1):

• Insertion Point
• Scale
• Rotation
• Anchor Point

To attach an Xref as it is in AutoCAD, set the scale on x=1.00 and y=1.00 and the Rotation angle to 0°.

To retain the World Coordinates of the Project, set the Insertion Point to x=0.00 and y=0.00 and the Anchor Point to Drawing's own origin.

Reference Type

The reference type specifies whether or not nested objects in the Xref file are displayed.

When the Xref contains other external references, those are called nested objects of Xrefs.

1. Attachment: all nested objects in all levels are displayed in the project file.
2. Overlay: nested objects from the Xref are not displayed.

Before attaching an Xref, close the AutoCAD file first.

Xref Attach is ideal for elements that are common to several kinds of drawings within a Project like topographic surveys. If you have a file containing this data, you can attach it to other drawings that can use the geometric information contained in the XREF file without the Project file actually having to contain the data. Also, if the source of the data in the external reference (the DWG or DXF) is changed, then these changes can be updated immediately so the latest data is always available.

Xref layers can't be unlocked, so you can't edit it.

Xref Manager

The Xref Manager allows you to have a global view of the Xrefs attached to your project. It also have a couple of functions that gives you control over the external references.

To access the Xref Manager, use:

File > External Content > Xref Manager

In the List or Tree view, all the Xrefs are displayed with their status, size, type and date of the last modification.

You can apply some functions to the selected Xref.

• Attach: by clicking on this button you attach a DWG file through the Attach Xref dialog box.
• Detach: to remove and external reference, click on this button. Xrefs are not deleted, they are detached.
• Reload: when the attached DWG file has been modified, click on reload. Archicad will load the whole file in ARCHICAD again. This button is also used to reload an unloaded Xref.
• Unload: you can attach an Xref without displaying it. Click on Unload to keep the selected external reference attached to your project, while unloading it from memory.
• Bind: by binding an Xref, you merge the DWG content to your project and delete the external reference from the Xref Manager. You can unlock the layers, then edit the drawing.

Layer management when attaching Xrefs

DWG/DXF Partial open

When you attach an Xref, there's a one step before having the DWG in you project: DWG/DXF Partial Open.

In this dialog box, you can choose which layers you want to import to Archicad.

The unchecked layers won't be imported and won't be listed in Layers. If you change your mind and want to import an unchecked layer, reload the Xref to have the Partial Open dialog box again and choose the layers you want to import.

Layer naming

When you attach an Xref, AutoCAD's layers will be renamed by adding a prefix containing the first ten characters of the Xref file name.

XREF_NAME | LAYER_NAME

Xrefs layers are listed in the Layers dialog box under the Archicad layers separated by a horizontal line. But if you bind the Xref, the horizontal line is removed. The name structure is the same though.

Here I shared with you how to use and manage External References in Archicad. I would like to hear about your experiences using Xrefs.

There is a third and last part for this series about working with CAD files in Archicad, so please subscribe to the AIM DESIGN Tutorials Newsletter so you don't miss the upcoming articles.

Hope this helps.