When the wheel is not moving, the eye can easily see the individual spokes. If the wheel is moved sufficiently, however, the eye can no longer recognize the individual spokes, since 16 to 18 images per second are sufficient for human perception to create the illusion of flowing motion. An example for "film images", with which the fast picture sequence becomes a flowing movement, are flip books.
Further informationson the exhibit "Aerial image"
In our exhibit, we make use of the weakness of the eye, because the moving spokes join together to form a projection surface on which we can then see a coherent Image.