•Known Size of Objects
–The nearer an object is to the observer, the larger its retinal image.
By experience, the brain learns to estimate the distance of familiar objects by the size of
their retinal image.
A structure projects a certain angle on the retina.
If this angle is large, the observer “sees” the object as being closer, and vice-versa. To use this cue, the observer must know the actual size of the object and have prior visual experience with it. Without this
experience, the observer must rely on motion
parallax to judge an object’s
distance.