To understand visual effects I had a brief look into optical, or visual illusions.
As explained, film is an illusion in itself, formed of still frames showed in a certain speed (24fps) creates movement. The way we see and interpret things gives the filmmaker space to experiment with effects, be it Special Effects, Visual Effects, they all experiment with the way we see and interpret images.
How we see things, our vision, depends on our eyes with the optic receptors (rods and cones) and the brain to make sense of what we see. An optic nerve connects the eye to the brain’s central nervous system and receives stimuli (electrical impulses) from the eyes. This is what we call sight. On top of this the brain adds perception, a mix of memory with interpretation. This gives room for manipulation and effects used in film are manipulations of perception (interpretation and expectation). If this is done in-camera or in post production.
A well known saying goes: “Seeing is believing”, but should we always believe what we see?
There are roughly three main categories of illusions; physical illusions happen before the light enters the eye, they create images that are different from the objects that make them, a rainbow is an example of a physical illusion. Physiological illusions are the results of exessive stimulation of a certain type on the eyes or brain, you can think of brightness, colour, movement. Last but not least are visual cognitive illusions. These are the most interesting and complicating ones, since they interact on different levels of interpretation of stimuli. We do this all the time and mainly unconsciously, but even when we are aware of what is happening, the illusion stays powerful.
M.C. Escher is one of the most well known graphic artists and famous for his impossible constructions. Goo Shun Wang made a short film “Halluci” based on visual perception and Escher’s Ascending – Descending. Halluci
Two other short videos interesting to watch are on hos stuff works. The first video is about the use of miniatures and distance in film, the second shows how a 3D optical illusion works.