What visual phenomenon helps determine the relative motion of stationary objects from a moving perspective?

Motion parallax is the phenomenon that occurs when an observer moves relative to stationary objects, resulting in a perception of motion based on their varying distances from the observer. As the observer moves, closer objects appear to move faster across the visual field than those that are farther away. This differential speed provides crucial information about the relative positions and distances of the objects in the environment.

For example, when you are driving and look out the side window, nearby trees or signs seem to whiz by, while distant mountains change position much more slowly. This effect is what allows observers to gauge how far away an object is, as the rate of apparent motion can signal whether an object is closer or further away.

This ability is particularly important in nighttime or low-visibility environments, such as when using night vision goggles, where the depth and distance of objects can be less intuitive. Understanding motion parallax helps to assess the environment more accurately, enhancing spatial awareness and navigation capabilities.