A realistic indoor scene is typically populated by several different kinds of furniture objects, but only a few of the many possible spa- tial arrangements of these objects are functional and livable. For example, the front of a television or computer screen should not be blocked, since it is supposed to be visible. Furthermore, most of the objects in the scene should be accessible to human habitants. On the other hand, one object is often placed on top of another object, such as a vase on a table, so there exists a hierarchical relationship among the two objects if we regard the carrier object as the parent and the.
