CONTROL METHOD FOR VISIBILITY INFORMATION ACQUISITION DEVICE AND VISIBILITY INFORMATION ACQUISITION DEVICE

In a visibility information acquisition device 1, a display control unit 32 displays a first identifier at a first position ahead of a subject S and subsequently displays a second identifier at a second position spaced in the front-back direction from the first position, and moves the viewpoint of the subject S from the first position to the second position. The display control unit 32 then controls the display state of the second identifier according to the transition condition, and causes the visibility of the second identifier to transition from a reference state to an intended state different from the reference state. The visibility information on the second identifier during transition is acquired by an information acquisition unit 34 from the subject S. Accordingly, information required to allow generation of a virtual space image that achieves visibility close to that of the appearance of a real space can be acquired at high accuracy when the viewpoint is moved.