Figure 3.

Computed perspective angles. A. Inferred angles between rails of a railway line as a function of the assumed distance of the vanishing point for three heights of the eye above the track. B. Inferred angles between the rails viewed in pictures (see Figure 4) as a function of the assumed distance of the vanishing point. The screen was positioned 0.57 m in front of the observer. The near ends of the rails were assumed to lie on the screen.