Environment Map
Command entry:Rendering menu Environment Environment And Effects dialog Environment panel Environment Map button
Command entry: Material Editor Raytrace material Maps rollout Environment button
Command entry: Material Editor Arch & Design material Special Purpose Maps rollout Environment button

You can use a map for the background of a scene. Reflection maps and Refraction maps also use environment coordinates instead of texture coordinates.

While texture coordinates project a map onto particular geometry, environment coordinates project a map onto the world coordinate system. If you move the object, the map remains in place. If you move the point of view, the view of the map changes. This type of mapping system is used with reflection, refraction, and environment maps.

Above: Image uses a picture as a background. The environment map uses screen coordinates.

Below: Image shows a checkered map applied to the environment using spherical mapping coordinates.

There are four types of environment coordinates:

The first three are the same as those used by the UVW Map modifier. If you imagine a sphere, infinite in size, surrounding your scene and mapped with spherical mapping coordinates, you can visualize the effect you get with spherical environment mapping. Shrink-wrap wraps the map around a giant sphere, leaving only one singularity. Cylindrical is like a giant cylinder.

The Screen system maps the image directly to the view, with no distortion. It’s similar to planar projection, in that it's like a giant backdrop hung behind the scene. Unlike the other environment mapping methods, Screen is locked to the view. When you move the camera, the map moves with it. Therefore, you can use screen coordinates only for still renderings, or animations in which the camera doesn't move.

To use a bitmap with any environmental mapping system other than Screen, you need a high-resolution map because of the size of the virtual sphere or cylinder.

To assign an environment map as the background of the scene, use the Environment And Effects Dialog Environment panel.

Editing an Environment Map

To edit or adjust a map you assign by using the Environment And Effects dialog, you need to use the Material Editor. There are a few different ways to do so:

NoteTo control whether or not the renderer uses the environment map's alpha channel in creating the alpha for the rendered image, choose Customize Preferences Rendering, and then turn on Use Environment Alpha in the Background Antialiasing group. If Use Environment Alpha is turned off (the default) the background receives an alpha of 0 (completely transparent). If Use Environment Alpha is turned on, the alpha of the resulting image is a combination of the scene and background image's alpha. Also, when writing TGA files with Pre-Multiplied Alpha set to off, turning on Use Environment Alpha prevents incorrect results. Only background images with alpha channels or black backgrounds are supported when compositing in other programs such as Photoshop.