Impossible crate
The impossible crate is an impossible figure , i.e. a three-dimensional optical illusion based on experience in spatial vision and the knowledge of geometric bodies and perspective laws .
The riddle
The box is presented to the viewer at a certain distance exactly as shown in Figure 1. The effect can be increased by having the demonstrator stand in the box. The viewer now thinks he is seeing a box that is made up of twelve slats and forms the edges of a cuboid that cannot exist as it is.
Experience tells the observer that both the upper front crossbar and the vertical slat in the foreground on the left (green in the 2nd figure) must be visually in front of the other slats due to the laws of perspective. Nevertheless, the viewer supposedly sees that the vertical bar on the right at the back and the transverse bar at the bottom (red) overlay these two, but this is impossible.
The solution
The delusion is based on the fact that the box is not what it appears to be. If you tilt the box a little, you can see that it does not consist of twelve continuous slats. As illustrated in Fig. 3, gaps in two of the laths have been so cleverly sawn that the laths behind can be seen through these gaps during the demonstration.
The illusion only succeeds when the distance from the viewer is sufficiently large and only when the viewer is not moving strongly. The spatial vision is based on the comparison of the two frames of the right and left eye; However, these individual images become more and more similar with increasing distance from the object being viewed, so that the depth or distance of an object is increasingly difficult to assess. When the viewer moves, he can estimate their actual position from the relative position of the objects: Experience shows that objects further away move less in the field of vision than closer ones.
Sufficient distance and relative immobility, for example with a fixed camera, deprive the viewer of these possibilities and his view is practically reduced to two dimensions, so that he is dependent on other reference values. Without information on depth, ultimately only a two-dimensional projection can be seen, which is extrapolated back to the third dimension on the basis of experience with such projections (e.g. illustrations in books, but also television images). The image of a cuboid is so familiar that something that is only sufficiently similar to it - such as the "impossible crate" - is involuntarily traced back to the familiar shape, even when the mind tells one that it is physically impossible .
The particularly impressive effect of such "impossible bodies" as the crate is based on the fact that they are actual bodies and not just their representations, but which are explicitly constructed with regard to the two-dimensional projection (and illusion) that they evoke. Due to the physicality, the seen is ascribed greater credibility than would be the case with a mere two-dimensional image.
Origin and use
The author of this and other “impossible bodies” is the British psychologist Richard Gregory , who dealt with sensory perceptions and illusions.
The "Impossible Lattenkiste" served the Dutch graphic artist MC Escher as a model for his lithograph "Belvedere".
