GLOSSARY
Matte objects are used to make the buildings in the foreground hide Kong’s legs
A matte object is invisible but blocks any geometry behind it. It does not, however, block the background.
For example, you might make a complex scene for the background of your animation, render it once, then assign the resulting bitmap as a background using only a few animated objects during the rendering of the animation. If you then needed one of your objects to appear from behind some portion of the background, such as a building, you would create a matte object that matches the building, then place the animated object behind it. The bitmap image of the building appears, but the animated object is blocked until it moves from behind the matte object.
Matte objects, though invisible, can cast shadows. However, they cannot receive shadows. In most cases, you should turn off the Casts Shadows property for a matte object.