2004
Table Of Contents
- Contents
- Chapter 1 - Find the Information You Need
- Part 1 - The User Interface
- Part 2 - Start, Organize, and Save a Drawing
- Part 3 - Control the Drawing Views
- Part 4 - Create and Modify Objects
- Chapter 14 - Control the Properties of Objects
- Chapter 15 - Use Precision Tools
- Chapter 16 - Draw Geometric Objects
- Chapter 17 - Change Existing Objects
- Part 5 - Hatches, Notes, and Dimensions
- Chapter 18 - Hatches, Fills, and Wipeouts
- Chapter 19 - Notes and Labels
- Chapter 20 - Dimensions and Tolerances
- Part 6 - Create Layouts and Plot Drawings
- Chapter 21 - Create Layouts
- Chapter 22 - Plot Drawings
- Part 7 - Share Data Between Drawings and Applications
- Chapter 23 - Reference Other Drawing Files (Xrefs)
- Chapter 24 - Link and Embed Data (OLE)
- Chapter 25 - Work with Data in Other Formats
- Chapter 26 - Access External Databases
- Overview of Using AutoCAD with External Databases
- Access a Database from Within AutoCAD
- Link Database Records to Graphical Objects
- Use Labels to Display Database Information in the Drawing
- Use Queries to Filter Database Information
- Share Link and Label Templates and Queries with Other Users
- Work with Links in Files from Earlier Releases
- Part 8 - Work with Other People and Organizations
- Chapter 27 - Protect and Sign Drawings
- Chapter 28 - Use the Internet to Share Drawings
- Chapter 29 - Insert and View Markups
- Chapter 30 - Publish Drawing Sets
- Part 9 - Create Realistic Images and Graphics
- Glossary
- Index
696 | Chapter 23 Reference Other Drawing Files (Xrefs)
If you turn on demand loading with the Enable with Copy option, AutoCAD
makes a temporary copy of the externally referenced file and demand loads
the temporary file. You can then demand load the xref while allowing the
original reference drawing to be available for modification. When you turn
off demand loading, AutoCAD reads in the entire reference drawing regard-
less of layer visibility or clip instances.
Layer and spatial indexes were added in AutoCAD Release 14 and AutoCAD
97. If you externally reference a drawing saved in an AutoCAD release
previous to this, you do not see the same performance benefit as drawings
saved with the indexes. For maximum performance, use demand loading
with referenced drawings saved with layer and spatial indexes turned on in
AutoCAD Release 14, AutoCAD 97, or more recent versions.
To turn on demand loading
1 From the Tools menu, choose Options.
2 In the Options dialog box, choose the Open and Save tab.
3 On the Open and Save tab under External References, select Disabled,
Enabled, or Enabled with Copy.
4 Choose OK.
Work with Layer and Spatial Indexes
To receive the maximum benefit of demand loading, it is recommended that
you save any drawings that are used as xrefs with layer and spatial indexes.
A layer index is a list showing which objects are on which layers. This list is
used when AutoCAD is referencing the drawing in conjunction with demand
loading to determine which objects need to be read in and displayed. Objects
on frozen layers in an external reference are not read in if the external refer-
ence has a layer index and is being demand loaded.
The spatial index organizes objects based on their location in 3D space. This
organization is used to efficiently determine which objects need to be read in
when the drawing is being demand loaded and clipped as an external refer-
ence. If demand loading is turned on, and the drawing is attached as an xref
and clipped, AutoCAD uses the spatial index in the externally referenced
drawing to determine which objects lie within the clip boundary. AutoCAD
then reads only those objects into the current session.