Provides options for viewport background display.
Alt+B
Synchronize with Display Mode Displays the background as a gradient if the environment is black, otherwise the Environment background is used. Exceptions are the Consistent Color, Hidden Line, Wireframe, Bounding Box, and ModelAssist display modes that have a solid grey background. Default=on.
Use Customize User Interface Gradient Colors (The default for Perspective viewports.) Displays the background as a gradient.
To customize the gradient colors, use the Customize User Interface dialog > Colors panel > Viewport Background Gradient Bottom and Viewport Background Gradient Top options.
Use Customize User Interface Solid Color (The default for axonometric viewports.) Displays the background as a solid color.
To customize the solid background color, use the Customize User Interface dialog > Colors panel > Viewport Background option.
Use Environment Background Displays the background specified on the Environment panel.
Use Files Displays an image used for viewports only.
You can display an image in one or all viewports. You might use images for modeling, for example, by placing front, top or side view sketches in the corresponding viewports. Or use a viewport background image to match 3D elements with digitized camera footage, or for rotoscoping.
You select the image or animation to display in the active viewport, set the frame synchronization between the animated image file and the current scene, and turn the assigned image on and off. These changes do not affect the rendered scene.
To place an image in the background of the rendered scene, use the Environment And Effects dialog > Environment panel, accessed from the Rendering menu.
Turn on to use an animated background. See To display an animated background. Default=off.
Controls the proportions of the viewport background by matching it to the bitmap, rendering output, or to the viewport itself.
Match Viewport
Changes the aspect ratio of the image to match the aspect ratio of the viewport.
Match Bitmap
Locks the aspect ratio of the image to the native aspect ratio of the bitmap.
Match Rendering Output
(The default.) Changes the aspect ratio of the image to match the aspect ratio of the currently chosen rendering output device.
Controls how sequences of images (for example, from IFL, AVI, or MOV files) are synchronized to the viewport for rotoscoping.
The first field sets the first frame of the incoming sequence that you want to use, and the second field sets the last one.
Sets the interval between the frames you want to use. For example, if this spinner is set to 7, 3ds Max uses every seventh frame.
Specifies the frame number at which you want the first input frame to appear. What happens in the viewport before the start frame depends on the option you choose for "Start Processing," below.
Determines which frame from your incoming sequence is displayed at the Start At frame. For example, you could have a 30-frame IFL sequence that starts in your scene at frame 10, but you could use the 5th frame from the IFL on frame 10 by setting Sync Start to 5.
Determines what happens in the viewport background before the start frame.
Determines what happens in the viewport background after the last input frame.
Displays the path and file name of the bitmap you have chosen.
Click to open a Select Background Image dialog, which lets you select a file or sequence of files for your background.
Click to remove the currently chosen background image.
To assign an image to one or all viewports:
Activate the viewport that is to display the background image.
Open the Viewport Configuration dialog to the Background panel (keyboard shortcut: Alt+B).
Choose Use Files.
In the Setup group, click the Files button.
This opens the Select Background Image dialog.
Use the dialog to open the image or animation to use.
To display the image in a single viewport, click Apply to Active View. To display the image in all viewports, click Apply to All Views in Active Layout Tab.
Click OK.
The image is displayed in a single viewport or all viewports.
To display the environment map in a viewport:
Use the Environment dialog to assign an environment map. (See the procedure “To choose an environment map.”)
In the Environment dialog > Background group, be sure Use Map is turned on (the default).
Activate the viewport where you want the map displayed.
Open the Viewport Configuration dialog to the Background panel (keyboard shortcut: Alt+B).
Choose Use Environment Background.
Click OK.
The map is displayed in the viewport.
To assign a viewport background by dragging and dropping:
Browse images in Windows Explorer or in another graphics-browsing application.
Select a thumbnail of the bitmap with your mouse and drag it onto an empty area of a viewport.
Do not drop the map onto an object: This creates a material instead of assigning a background.
3ds Max opens the Bitmap Viewport Drop dialog:

When on, puts the bitmap into the viewport as a background.
When on, includes the bitmap when you render the viewport.
Click OK.
To display an animated background:
Choose Use Files and assign an animation file (AVI, MOV, or IFL file) as the viewport background.
Turn on Animate Background.
Choose Customize > Preferences. On the Viewports panel, turn on Update Background While Playing.
Now the background plays when you click Play, or when you drag the time slider.
To use the environment map with animation controls:
This procedure is useful if you’ve assigned an animated environment map and want access to the animation controls on the Background panel.
On the Viewport Configuration dialog > Background panel, choose Use Files.
As the image file, choose the same map you’re using as the environment map.
Set parameters in the Animation Synchronization group.
Click OK.
The environment map appears in the viewport. The image is renderable.
To match the viewport background with the rendered background:
Activate the viewport to render.
Open the Point-Of-View (POV) Viewport label menu and choose Show Safe Frames.
This turns on Safe Frames in the viewport.
In the Material Editor, create a material that contains the bitmap for your rendered background.
At the bitmap level of the Material Editor, on the Coordinates rollout, choose Environ.
The Mapping control is automatically set to Screen. This is the only mapping type that works for this purpose.
On the main menu, choose Rendering > Environment.
Drag the map from the Material Editor > Maps rollout to the Environment Map button on the Environment dialog. Click OK on the Instance (Copy) Map dialog.
In the Viewport Configuration dialog > Background panel, choose Use Files and then click Files to assign the same bitmap.
In the Aspect Ratio group, choose either Match Viewport or Match Rendering Output. Click OK.
Render the viewport.
The background displayed in the rendered scene should exactly match the background displayed in the Live area of the safe frames.
To remove a background image: