How the World’s First 3-D Movie tricked our Brain

Figure 1. A still from ‘L’Arrivée du Train’, you can watch this pioneering clip here.

In the very beginnings of of the 20th century, in 1903, the legendary Lumière Brothers released the world’s first 3D movie- “L’Arrivée du Train”, which translates to ‘Arrival of a Train’. It might be more accurate to call it a clip than a movie, but it was sufficient to convince the audience that ‘they were being run over by the train’. But soon feature-length movies that we are now accustomed to followed, with titles such as ‘The Power of Love’ and ‘Bwana Devil’.

Nowadays, every other movie released is available to be viewed in 3-D. Viewing in 3-D makes the movie come alive, as if the snowflakes on the screen are dusting and dancing about you. While current 3-D technology has come a long way, at the heart of this technique lies the simple idea of Stereoscopy.

Stereoscopy is a depth cue that reveals depth perception. There are other cues to aid depth perception such as light and shade or texture gradients, but these cues can be perceived even if you close one of your eyes, hence they are termed ‘monocular cues’.

Stereoscopy on the other hand, only occurs with the aid of both eyes and is termed ‘binocular cue’. If you close your eyes and then peek at the same object in front of you, opening your eyes alternatively, you will quickly realize that each of your eye observes the same object, differently. Our brain, perceives this difference of input from both eyes as depth.

Figure 2. Anaglyph glasses. Photo by Snaily — Own work CC BY-SA 3.0

To understand how cinema utilizes our stereoscopic vision, imagine you are given a pair of glasses. The lens on either side of the glasses have different colored lenses, usually red paired with cyan/green (Figure 2.). Now these movies are edited in such a manner that they show two superimposed images printed usually with red paired with cyan/green, that can only be perceived clearly using the red/cyan glasses (Anaglyph glasses), creating an illusion of depth to the audience watching a movie through these glasses. If you have noticed, removing your glasses can make the same movie seem mildly incoherent and blurry.

Essentially, here the glasses act as a mechanism to correct the conflicting images of the movie, not unlike our brain, and create the perception of depth.

References:

Devernay, F., & Beardsley, P. (2010). Stereoscopic Cinema. Image and Geometry Processing for 3-D Cinematography, 11–51