Blending an Object into the Background

In the Procedures section (following), you'll learn how to blend an object into the background with the Camera Map modifier. If the background uses the same image as the object's texture map, then the object blends with the background at the frame where the modifier is applied and a camera is specified. The object becomes visible if either the camera or object moves. In order to make the illusion work, you must assign the same map to the background that you assign to the object.

Mapping Coordinates

Because the accuracy of mapped objects depends partly on the complexity of the mesh, the "blend to background" effect works best when applied to an object with a relatively high density of triangular faces. The necessary density also depends on the distance of the object from the camera.

A simple box might look fine when it occupies only a small portion of the background, but up close the mapping will look distorted without adequate tessellation. Some experimentation is required to get an ideal mapping and still minimize the complexity of the geometry. (In general, for a box object that's filling a quarter of the screen, a tessellation of 4x4x4 works well.)

Use Camera Map (WSM) if you want to move the camera and maintain the match to the background.

Using the Plate Match/MAX R2.5 Rendering Filter

Prior to 3ds Max 3, the antialiasing affected only geometric edges, with the filtering of bitmaps being controlled in the Bitmap Map parameters (pyramidal, summed area, or no filtering). Antialiasing filters affect every aspect of the object, filtering textures along with geometric edges. While antialiasing provides superior results, it produces inconsistencies when rendering objects that are supposed to match the environment background. This is because the antialiasing filters do not affect the background by default. You can turn on background antialiasing in Customize Preferences Rendering Background Antialiasing Filter Background. To correctly match an objects map to an unfiltered background image, you need to use the Plate Match/MAX R2.5 filter so the texture is not affected by the antialiasing.

There are three ways you can render objects in 3ds Max to blend seamlessly into a background environment:

• By assigning a Matte/Shadow Material
• By assigning a 100% self-illuminated diffuse texture to an object using Camera Mapping
• By assigning a 100% self-illuminated diffuse texture using Environment/Screen projection

The Plate Match/MAX R2.5 antialiasing should be used whenever trying to match foreground objects with an unfiltered background or when trying to match the antialiasing qualities of the 3ds Max 2.5 renderer.

Procedures

The following steps show how to apply the Camera Map modifier, and how to set up your scene.

To apply the Camera Map modifier:

1. Create a scene with a camera and one or more objects. Make sure the object you want to map is visible in the Camera viewport.
2. Select the object, and apply the Camera Map modifier.

   Be sure to use the Object-Space version of the Camera Map modifier.

3. If you have animation in the scene, move to the frame where you want the object map to match the background. For example, if the camera is animated, the mapping will match only at this frame.
4. On the Camera Mapping rollout, click Pick Camera, and then select the camera used for the rendered view.

To assign a background image to the Camera viewport:

1. Activate the Camera viewport and turn off the grid.
2. Choose Views menu Viewport Background.
3. On the Viewport Background dialog that displays, click the Files button, and choose the same bitmap that you plan to apply as a background for the rendered scene, and as a diffuse map on the object.
4. In the Aspect Ratio group, choose Match Rendering Output.
5. Turn on Display Background, and click OK.

   3ds Max closes the dialog and displays the map in the viewport.

To assign a mapped material to the object:

1. In the Material Editor, create a standard material to whose Diffuse component you've assigned the same bitmap as you assigned to the background.
2. At the Diffuse Map level of the material, turn on (Show Map In Viewport).
3. Select the object, and click (Assign Material To Selection).

   The map on the object in the viewport matches the viewport background, but the shading makes the object visible. To make the object truly invisible, go to the next step.

4. At the top level of the object's material, set Specular Level and Glossiness to 0. Turn off Self Illumination Color, and set Self Illumination to 100.

   The object is now camouflaged against the background.

To assign the background to the rendered background:

1. Choose Rendering menu Environment.
2. In the Environment dialog that displays, click the button below "Environment Map" to open the Material/Map Browser.
3. Under the Browse From group box, choose Material Editor.
4. Turn off Root Only, find the map in the list window, highlight it, and choose OK.
5. Choose Copy in the dialog, and click OK.
6. In the Exposure Control rollout on the Environment dialog, make sure the exposure is set to <no exposure control> or the turn off the Active switch.

   If you don’t do this, you will be able to see the object in the rendering.

7. Render the Camera viewport.

   The mapped object is camouflaged against the background in the rendered scene.

Interface

Pick Camera

To apply the UVW coordinates, click this button, and then select the camera through which you're going to view the scene.

Map Channel

Turn on and choose a map channel to use. Map channels are specified in the Material Editor.

Vertex Color Channel

Uses the Vertex Color channel.