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Xrefing with Friends
Tip# 3687 By Danny Korem On 17-Jul-2011
Rated By 0 users
Categories : DWG
Software type : AutoCAD 2012
Rename File To : No Files to download.
The Demand Loading and VisRetain settings can save you from duplicate work.

Frequent tipster Danny Korem discusses some AutoCAD settings to consider when referencing other files and sharing them with coworkers.

"When cooperating, life gets more complicated than when working solo — and it's true in AutoCAD as well. There are two issues involved:

  1. When sharing a network workspace, the Demand Load of xreferences must be carefully considered.
  2. You can retain (or lose) visibility of xref attachments within your file.

This is especially important if several users are united in a particular effort. In current versions of AutoCAD, the VisRetain option can be found at the Open and Save tab in Software Options, in the External References (xrefs) area, in the middle-right of the dialog box. If you won't be working solo, it's a must to check the 'retain changes to xref layers' box. Checking this option will cause AutoCAD to 'remember' all changes made to the xref layers within the current DWG file. It will remember the status, both in the case of closing and reopening the file and in the case of getting a new updated version of the referenced file.

"It can be very frustrating to find out that you have to redo something. This option should be activated in all workstations at your office so nobody can cause anybody else to do any unnecessary work ever again."
Notes from Cadalyst Tip Patrol: There are two settings discussed in this tip. Out of the box, AutoCAD comes with these settings turned on, so it's possible many users don't even realize that the software can behave differently.

The first of these settings is Demand Loading, which causes AutoCAD to load into memory only the data from the reference drawing that is necessary to regenerate the current drawing. In short, it loads only what is demanded of it. This makes sense; why load parts of an xref file that you don't need? If you xclip an xref, demand loading means that it will not load the clipped area into memory until you remove or change the clipped area. It saves memory and processor time. You can turn this off, but I don't know why you would want to.

The second setting is VisRetain, which controls the visual retention of settings in your current file. Imagine that a base file has a layer called ABC, with a color of white and a linetype set to continuous. When you xref that base file, your file visually displays layer ABC as a white continuous line. You can override that setting in your file without changing the base file. These settings are "retained" by the VisRetain setting. If VisRetain was turned off, you would lose any changes when you closed the file.


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User comments
Comment by Baker II,Richard L.
Posted on 2011-07-18 14:09:28
There is one thing you forgot to mention in regards to the Demand Loading feature. Before AutoCAD can demand load any drawing information, the drawing must be saved with the Layer & Spatial Indexes turned on. Without that information AutoCAD will not be able to determine what information needs to be loaded. To turn on the indexes, access the Options command from the Tools menu on the Save or SaveAs dialogs. In the Index Type select the Layer & Spatial indexes. I typically save my templates with this setting turned on so any drawing I create will already have the indexes set.
Comment by Baker II,Richard L.
Posted on 2011-07-18 14:23:44
Another way to turn on the Layer & Spatial indexes is to use the INDEXCTL system variable. Here are the valid values. 0 - Off 1 - Layer 2 - Spatial 3 - Layer & Spatial See AutoCAD's help for more information.