Figure 6.

Visual directions. (a) Visual directions of the center of the physical 30 km traffic sign standing at the left side of the road (red) and the mailbox of the distant house (blue) as function of camera position. The origin of the camera-position scale is given in Figure 2a. (b) Visual directions as function of viewing distance of the picture (r_p). The solid blue line shows the visual direction of the mailbox in the 36 mm picture of Figure 1a, the dashed blue line, of the mailbox in the 72 mm picture of Figure 1b. Thin lines mark the viewing distances at which the visual directions of projected objects are equal to the visual directions of the physical objects (see Figure 2a). (c) Ratio between visual directions of the physical house and traffic signs shown in (a). (d) Ratio between visual directions of the depicted house and traffic signs shown in (b). The solid line shows the ratio in the 36 mm picture and the dashed line in the 72 mm picture.