Final answer:
The cue where two parallel lines appear to converge in the distance is known as linear perspective, a phenomenon that creates an illusion of depth and is employed in both art and practical applications like surveying.
Step-by-step explanation:
The distance cue in which two parallel lines extend into the distance and seem to converge at one point is called linear perspective. This optical illusion is a result of the way our vision interprets the parallel lines as they recede into the distance, such as when looking at train tracks or a distant road. For instance, in Wolf Vostell's photograph from his No: Life as a Picture-A Picture as Life series from 1963, this effect is clearly seen. Similarly, in Perugino's painting, orthogonals can be observed converging at the vanishing point on the horizon line, and as they converge, the forms also appear smaller, creating a sense of depth. This concept is not only utilized in art but is also applied in practical situations, such as in surveying, where the measurement of distance through the baseline and parallax takes advantage of similar principles.