Referencing External Objects

No man is an island, and if Autodesk has its way, no Max user will be an island either. XRefs (which stands for eXternal References) make it easy for creative teams to collaborate on a project without having to wait for another group member to finish his or her respective production task. External references are objects and scenes contained in separate Max files and made available for reference during a Max session. This arrangement enables several artists on a team to work on separate sections of a project without interfering with one another or altering each other's work.

Max includes two different types of XRefs: XRef scenes and XRef objects. You also can use XRef for materials, modifiers, and controllers.


The ability to XRef controllers is new to 3ds Max 9.

Using XRef scenes

An externally referenced scene is one that appears in the current Max session, but that is not accessible for editing or changing. The scene can be positioned and transformed when linked to a parent object and can be set to update automatically as changes are made to the source file.

As an example of how XRef scenes facilitate a project, let's say that a design team is in the midst of creating an environment for a project while the animator is animating a character model. The animator can access the in-production environment as an XRef scene in order to help him move the character correctly about the environment. The design team members are happy because the animator didn't modify any of their lights, terrain models, maps, and props. The animator is happy because he won't have to wait for the design team members to finish all their tweaking before he can get started. The end result is one large, happy production team (if they can meet their deadlines).

Choose File image from book XRef Scenes to open the XRef Scenes dialog box (shown in Figure 3.19), which you use to load XRef scenes into a file.

image from book
Figure 3.19: The XRef Scenes dialog box lets you specify which scenes to load as external references.

XRef scene options

In the XRef Scenes dialog box are several options for controlling the appearance of the scene objects, how often the scene is updated, and to which object the scene is bound. This dialog box is modeless, and you can open and change the options in this dialog box at any time.

The pane on the left lists all XRef scenes in the current scene. These scenes are displayed using their full path unless the Convert Local File Paths to Relative option in the Files panel of the Preference Settings dialog box is enabled. To the right are the settings, which can be different for each XRef scene in the list. To view or apply a setting, you first need to select the scene from the list. You can remove any scene by selecting it from the list and clicking the Remove button.


If an XRef scene in the list is displayed in red, then the scene could not be loaded. If the path or name is incorrect, you can change it in the Path field at the bottom of the list.

The Convert Selected button converts any selected objects in the current scene to XRef objects by saving them as a separate file. This button opens a dialog box to let you name and save the new file. If no objects are selected in the current scene, then this option is disabled.

Use the Enabled option to enable or disable all XRef scenes. Disabled scenes are displayed in gray. The Merge button lets you insert the current XRef scene into the current scene. This button removes the scene from the list and acts the same way as the File image from book Merge command.

Updating an external scene

Automatic is a key option that can set any XRef scene to be automatically updated. Enable this option by selecting a scene from the list and checking the Automatic option box; thereafter, the scene is updated anytime the source file is updated. This option can slow the system if the external scene is updated frequently, but the benefit is that you can work with the latest update.

The Update Now button is for manually updating the XRef scene. Click this button to update the external scene to the latest saved version.

External scene appearance

Other options let you decide how the scene is displayed in the viewports. You can choose to make the external scene invisible or to display it as a box. Making an external scene invisible removes it from the viewports, but the scene is still included in the rendered output. To remove a scene from the rendered output, deselect the Enabled option.

The Ignore section lists objects such as lights, cameras, shapes, helpers, and animation; selecting them causes them to be ignored and to have no effect in the scene. If an external scene's animation is ignored, then the scene appears as it does in frame 0.

Positioning an external scene

Positioning an external scene is accomplished by binding the scene to an object in the current scene (a dummy object, for example). The XRef Scenes dialog box is modeless, so you can select the object to bind to without closing the dialog box. After a binding object is selected, the external scene transforms to the binding object's pivot point. The name of the parent object is also displayed in the XRef Scenes dialog box.

Transforming the object to which the scene is bound can control how the external scene is repositioned. To unbind an object, click the Unbind button in the XRef Scenes dialog box. Unbound scenes are positioned at the World origin for the current scene.

Specifying an XRef as an Overlay

The Overlay option in the XRef Scenes dialog box makes the XRef visible to the current scene, but not to any other scenes that XRef the scene including the overlay. This provides a way to hide XRef content from more than one level. Overlay XRefs also make it possible to avoid circular dependencies. For example, in previous Max versions, Max wouldn't allow two designers to XRef one another's scenes, but if one of the scenes is an overlay, then this can be done.

Working with XRef scenes

You can't edit XRef scenes in the current scene. Their objects are not visible in the Select by Name dialog box or in the Track and Schematic Views. You also cannot access the Modifier Stack of external scenes' objects. However, you can make use of external scene objects in other ways. For example, you can change a viewport to show the view from any camera or light in the external scene. External scene objects are included in the Summary Info dialog box.


Another way to use XRef scenes is to create a scene with lights and/or cameras positioned at regular intervals around the scene. You can then use the XRef Scenes dialog box to turn these lights on and off or to select from a number of different views without creating new cameras.

You can also nest XRef scenes within each other, so you can have one XRef scene for the distant mountains that includes another XRef for a castle.


If a Max file is loaded with XRef files that cannot be located, a warning dialog box appears, enabling you to browse to the file's new location. If you click OK or Cancel, the scene still loads, but the external scenes are missing.

Tutorial: Adding an XRef scene

As an example of a project that would benefit from XRefs, I've created a maze environment. I open a new Max file and animate a simple mouse moving through this maze that is opened as an XRef scene.

To set up an XRef scene, follow these steps:

  1. Create a new Max file by choosing File image from book New.

  2. Choose File image from book XRef Scenes to open the XRef Scenes dialog box.

  3. Click the Add button, locate the image from book Maze.max file from the Chap 03 directory on the DVD, and click Open to add it to the XRef Scene dialog box list, but don't close the dialog box just yet.


    You can add several XRef scenes by clicking the Add button again. You can also add a scene to the XRef Scene dialog box by dragging a .max file from Windows Explorer or from the Asset Manager window.

  4. Select Create image from book Helpers image from book Dummy, and drag in the Perspective viewport to create a new Dummy object.

  5. In the XRef Scenes dialog box, click the Bind button and select the dummy object. This enables you to reposition the XRef scene as needed.

  6. Select the Automatic update option, and then click the Close button to exit the XRef Scene dialog box.

  7. Now animate objects moving through the maze.

Figure 3.20 shows the image from book Maze.max scene included in the current Max file as an XRef.

image from book
Figure 3.20: The maze.max file loaded into the current file as an XRef scene


With the simple mouse animated, you can replace it at a later time with a detailed model of a furry mouse using the File image from book Replace command.

Using XRef objects

XRef objects are slightly different from XRef scenes. XRef objects appear in a scene and can be transformed and animated, but the original object's structure and Modifier Stack cannot be changed.

An innovative way to use this feature would be to create a library of objects that you could load on the fly as needed. For example, if you had a furniture library, you could load several different styles until you got just the look you wanted.

You can also use XRef objects to load low-resolution proxies of complex models in order to lighten the system load during a Max session. This method increases the viewport refresh rate.

Many of the options in the XRef Objects dialog box, shown in Figure 3.21, are the same as in the XRef Scenes dialog box.

image from book
Figure 3.21: The XRef Objects dialog box lets you choose which files to look in for external objects.

The interface buttons for the XRef Objects dialog box are listed in Table 3.1.

Table 3.1: XRef Objects Dialog Box
Open table as spreadsheet




image from book

Create XRef Record from File

Opens the XRef Merge dialog box where you can select the XRef source file.

image from book

Remove XRef Record

Deletes the selected XRef record.

image from book

Combine XRef Record

Allows two or more selected XRef records pointing to the same file to be combined into a single record.

image from book


Updates the content of all XRefs.

image from book

Merge in Scene

Makes all XRefs for the selected record part of the scene file. This also removes the XRef record from the dialog box.

image from book

Convert Selected Objects to Xrefs

Opens a save dialog box, and saves the selected scene objects as a separate scene file, which is an XRef in the current scene.

image from book


Selects the objects that are part of the selected XRef record.

image from book

Select by Name

Opens the Select Objects dialog box listing all objects that are part of the selected XRef record.

image from book

Highlight Selected Object's XRef Records

Highlights the XRef record that contains the objects selected in the viewport.

image from book

Add Objects

Opens the XRef Merge dialog box where additional objects from the selected XRef record can be loaded.

image from book

Delete XRef Entity

Deletes the current object from the XRef record.

image from book

Merge in Scene

Merges the selected object to the current scene and removes its XRef.

image from book

List Objects

Filters the display to show the XRef objects.

image from book

List Materials

Filters the display to show the XRef materials.

image from book

List Controllers

Filters the display to show the XRef controllers.

The XRef Objects dialog box is divided into two sections. The top section displays the externally referenced source files (or records), and the lower section displays the objects, materials, or controllers selected from the source file. If multiple files are referenced, then a file needs to be selected in the top pane in order for its objects and materials to be displayed in the lower pane.

The Convert Selected button works the same as in the XRef Scenes dialog box. It enables you to save the selected objects in the current scene to a separate file just like the File image from book Save Selected command and to have them instantly made into XRefs.

In the XRef Objects dialog box, you can choose to automatically update the external referenced objects or use the Update button or you can enable the Automatic Update option. You can also enable or disable all objects in a file with the Enabled option. The Include All option skips the XRef Merge dialog box and automatically includes all objects in the source file.

If the Merge Transforms, Merge Materials, and Merge Manipulators options are enabled before an XRef file is added, then all transforms, materials, and manipulators are automatically combined with the current scene instead of being referenced. When merged, the link between the source file is broken so that changes to the source file aren't propagated.


The Merge Transform button is new to 3ds Max 9. It lets you choose whether the transform controllers are merged with the object or whether they stand as their own XRef record.

Using material XRefs

When a source file is loaded into the XRef Objects dialog box, both its objects and materials are loaded and included. If the Merge Materials option is selected before the source file is loaded, then the materials are included with the objects, but if the Merge Materials option isn't enabled, then the objects and the materials appear as separate entities. You can use the List Objects and the List Materials buttons to list just one type of entity.

Materials also can be referenced from directly within the Material Editor. If you used a material in a previous scene that would be perfect in your current scene, you can just select the XRef Material from the Material/Map Browser. This material type includes fields where you can browse to an external scene file and select a specific object. The selected material is added automatically to the XRef Objects dialog box.


You can learn more about applying materials and using the Material Editor in Chapter 20, "Exploring the Material Editor."

Merging modifiers

If the Merge Manipulators option is enabled before loading the XRef file, then any manipulator that is part of the XRef object is merged and loaded along with the object. You also can specify how modifiers are included with XRef objects, but you must select the option from the Modifier drop-down list before the file is selected. The XRef option loads all modifiers with the XRef object, but hides them from being edited. New modifiers can be added to the object. The Merge option adds all modifiers to the XRef object and makes these modifiers accessible via the Modifier Stack. The Ignore option strips all modifiers from the XRef object.

XRef objects appear and act like any other object in the scene. You may see a slight difference if you open the Modifier Stack. The Stack displays "XRef Object" as its only entry.

Using proxies

When an XRef object is selected in the viewport, all details concerning the XRef object-including its source file name, Object Name, and status-are listed in the Modify panel. The Modify panel also includes a Proxy Object rollout, where you can select a separate object in a separate file as a proxy object. The File or Object Name buttons open a file dialog box where you can select a low-resolution proxy object in place of a more complex object. This feature saves memory by not requiring the more complex object to be kept in memory. You also can select to enable or disable the proxy or use the proxy in rendering.


The real benefit of using proxies is to replace complex referenced objects with simpler objects that update quickly. When creating a complex object, remember to also create a low-resolution version to use as a proxy.

Controller XRefs

In addition to objects, materials, and modifiers, controllers also can be externally referenced. This means that you can borrow the controller motions of an object in a separate scene and save some animation time. To reference an external controller, select the Transform track and choose the XRef Controller option. This opens a File dialog box followed by a Select Object dialog box where you can choose with the controller the object that you want to reference. XRef controllers also appear as records in the XRef Objects dialog box.


You can learn more about applying and using controllers in Chapter 32, "Animating with Constraints and Controllers."

Tutorial: Using an XRef proxy

To set up an XRef proxy, follow these steps:

  1. Open the image from book Post box with XRef tree.max file from the Chap 03 directory on the DVD. This file includes the post box model produced by Zygote Media.

  2. Open the XRef Objects dialog box by choosing File image from book XRef Objects.

  3. Click the Create XRef Record from File button, and locate the image from book Park bench under a tree.max file from the Chap 03 directory on the DVD.

    This file includes the old tree and park bench models made by Zygote Media. The XRef Merge dialog box, shown in Figure 3.22, automatically opens and displays a list of all the objects in the file just added.

    image from book
    Figure 3.22: The XRef Merge dialog box lets you choose specific objects from a scene.

  4. Select the Tree object to add to the current scene, and click OK.


    If an object you've selected has the same name as an object that is currently in the scene, the Duplicate Name dialog box appears and lets you rename the object, merge it anyway, skip the new object, or delete the old version.

  5. Select the Tree object in the lower pane of the XRef Objects dialog box, and click the Select button. The tree object is selected in the viewport. Close the XRef Objects dialog box.

  6. With the tree object selected, open the Modify panel, enable the Enable option, and click the button under the File Name field to open a file dialog box. Select the image from book Tree Lo-Res.max file from the Chap 03 directory on the DVD, and click the Open button.

    The Merge dialog box opens.

  7. Select the Cylinder01 object, and click OK.


    If the proxy object has a different offset than the original object, a warning dialog box appears instructing you to use the Reset XForm utility to reset the transform of the objects.

  8. With the Tree object still selected, disable the Enable option in the Proxy Object rollout to see the actual object.

XRef objects that you add to a scene instantly appear in the current scene as you add them. Figure 3.23 shows the post box with the actual tree object. The Modify panel lets you switch to the proxy object at any time.

image from book
Figure 3.23: The tree object is an XRef from another scene. Its proxy is a simple cylinder.

Configuring XRef paths

The Configure Paths dialog box includes an XRefs tab for setting the paths for XRef scenes and objects, shown in Figure 3.24. Choose Customize image from book Configure User Paths to open the XRefs panel.

image from book
Figure 3.24: The XRefs panel in the Configure User Paths dialog box lets you specify paths to be searched when an XRef cannot be located.

Max keeps track of the path of any XRefs used in a scene, but if it cannot find them, it looks at the paths designated in the XRefs panel of the Configure Paths dialog box. For projects that use lots of XRefs, populating this list with potential paths is a good idea. Paths are scanned in the order they are listed, so place the most likely paths at the top of the list.

To add a new path to the panel, click the Add button. You can also modify or delete paths in this panel with the Modify and Delete buttons.

3ds Max 9 Bible
3ds Max 9 Bible
ISBN: 0470100893
EAN: 2147483647
Year: 2007
Pages: 383

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