Our two eyes provide our brain with images slightly spaced from one another and that provides the brain with visual clues sufficient to create a 3D representation of what is “out there”. The light and the shadows are very important clues as well. When we look at a photo printed on a sheet of paper or displayed on a screen, the light, shadows, size and level of details all together provide good clue to our brain for a “feeling” of depth. This is why when looking at a 4k screen displaying high resolution clips we can feel the depth of the image.
A much better clue, however, is provided if each eye were seeing two slightly separated images, as it happens when we look at the real world.
There are a number of “technical tricks” to do this and most of them involve wearing a special pair of glasses that alternate two slightly spaced images to our eyes. This is not convenient: if you are already wearing glasses getting one more on your nose is not nice, and if you are not wearing glasses… well, you are not used wearing them!
There are also ways to show two different images by using some mechanical/optical mechanism so that your eyes end up seeing different parts of the screen, and hence two different images.
This works well provided you are at a certain distance from the screen and don’t move. These solutions, however, do not work if there are several persons looking at the screen since they cannot look at it from the same place.
Now, as reported in a paper submitted by MIT researchers at SIGGRAPH 2016, there can be a way to view different images without wearing glasses in a cinema.
The trick, because there is always a trick!, is to leverage on the fixed position that every person has in the cinema. Each one is seated in a seat at a very precise position and has no way of moving around. Hence, the researchers observed, it is possible to create a mechanisms made of mirrors and lenses that provide individual screen images to each seat (person).
The display, called automultiscopic, provides very narrow angular range images of the screen, each one visible from a very specific seat.
The mechanisms is quite complex and you won’t be experiencing it anytime soon. Still, it is nice to see the ingenuity of researchers to circumvent what would seem to be an impossible feat!