- The way the shapes of objects change as the player moves around the game environment. In 2D environments, rigid objects retain their projected shape as they change position and orientation due to player motion, while in 3D environments their apparent shape can change significantly.
- The way the angles between objects change as the player orbits around a particular point or travels along a path1, as measured from the camera's perspective. In 3D environments the apparent angles between objects are significantly affected as the player moves around, but remain fixed in 2D views.
1. If the player is moving along a straight line, angles between objects will change only if parallax is present.