Close one eye. You can still perceive depth, right?

That's because knowing where things are is so important, that our visual system does an excellent job of depth perception - even with the loss of an eye.

Centuries ago, Renaissance painters finessed and popularized 2D optical tricks to achieve a 3D effect on a flat surface. These same monocular cheats are now used widely in computer graphics (aka, cgi "3D").

But - if you aren't convinced our binocular vision is a major advantage - close one eye and try catching a ball. While monocular cues are critical to our perception of depth, they (and cgi "3D") can not create the experience of real 3D.

Real 3D requires

• Two different 2D images of the same scene, with objects in correct parallax
• Technology that enables stereopsis

What???

First, stereopsis: You're experiencing it right now. Our binocular vision works by sending two dissimilar 2D images (a "stereo pair," one from each eye) to the visual cortex in the brain, which fuses those two flat images into a single 3D perception. This phenomenon is called "stereopsis," first described by Charles Wheatstone in 1838. He also invented the 1st 3D viewer (aka, stereoscope) the same year. Second, parallax: To understand how your brain sees in 3D, hold your thumb out at arms' length. Close one eye and then the other. See how your thumb appears to change positions? This perceived shift in position caused by a change in the point of observation is called "parallax." Parallax provides the brain its only "binocular cue." Wider "interaxials" (distance between a stereocamera's 2 lenses) can increase parallax and exaggerate the 3D effect. Some 3D artists tweak parallax to great effects, but the general rule of thumb is to adjust stereocamera lenses to 1/30 of the distance to your nearest object. For example: if the nearest object is 7.5 feet away, the lenses should be 3 inches apart (90" x 1/30). Finally, technology: The trick to achieve real 3D on a 2D (flat) surface is how to show each eye the correct image - and only that image. This sounds very complicated, but early market demand for 3D drove inventors to patent many different types of 3D viewing technologies. The advent of photography (also mid-1800's) spawned the 1st 3D boom. Exotic places and portraits were especially popular, since travel was costly and dangerous. By the early 1900's, consumer stereoscope viewers were as ubiquitous as radio and TV would become. The Lumiere brothers shot the 1st 3D movie "L'arrive d'un train" in 1895 with their all-in-one camera/developer/projector, which eventually led to the 1st 3D movie boom in 1953.

3D: The 3rd Dimension The 3rd dimension occurs on the z-axis (depth). 2D occurs on one flat plane, created by the x-axis (width) and the y-axis (height). You can see how "monocular cues" in this 2D image provide enough information to understand depth - but, this is not real 3D. For real 3D, you still need glasses, unless you are looking at a lenticular or lucky enough to own an autostereoscopic monitor. 3D artists exploit both the z-axis and monocular cheats to enhance the perception of immersion. Monocular = "one eye" Binocular = "two eyes"       Monocular cues include: Texture gradient - distant objects appear to be smaller and packed closer together Interposition - distant objects appear behind closer objects Perspective - parallel lines converge together as they get further away Arial perspective - distant objects are less sharp and more distorted Shading - distant objects have different light direction

Advancements in 3D technology allow for a fantastic cinema experience today, but limitations for home viewing still present a challenge. Polarized HD-3D monitors and autostereoscopic displays will drive the next revolution of at-home entertainment, as that technology improves and costs come down in the near future. However, there are lots of 3D technologies you can enjoy at home today.

The demands and limitations of 3D production require expertise, creativity and artistry to create the illusion of no limitations. Contact The Brain Factory to brainstorm how to get the most out of your 3D project.



Learn About Anaglyph 3D
Learn About Lenticulars
Learn About Side-by-Side Stereo Pair 3D
Learn About Chromadepth 3D
Learn About Pulfrich 3D