Check out these illusions:
These illusions are but another example of the truth that it is the brain that sees, not the eyes. This is a very important concept to keep top of mind when creating 3D imagery. By presenting a different perspective to each eye, the brain takes that input and converts it to an image with depth. In the case of 3D imagery – the imagery provides an illusion that the brain processes and interprets as a real depiction of space. In truth, the space does not exist – it is an illusion.
As with all illusions, there is a point where the illusion breaks down. Since it is an illusion and NOT real, by definition there will be limitations to what can be presented in 3D. Few understand that the brain will never fully accept an illusion without some level of perception conflict. It might be suppressed and deep within the subconscious, but there will always be a slight difference between what we see in real life and what is presented in the form of an illusion. But as the above examples demonstrate, there are aspects to illusion that present as very real because the brain is highly biased to process information in certain ways. Taking advantage of this bias makes it possible to create incredibly compelling 3D imagery. Ignoring it and what you end up with is far less effective.
So, thinking about 3D as an illusion, instead of mimicking the mechanics of presenting information to the eyes in a familiar way, opens up many more possibilities for compelling multi perspective imagery. Many times, what you think you are seeing is far more powerful than what you actually are seeing.
An additional follow up tidbit: By engaging the brain with a visual puzzle, you latch into engagement and fixation and open up the possibilities to communicate a great deal of information within a multi perspective image. In this way, 3D is a tool that makes new types of artistic expression possible.