A 3D optical illusion of sorts is making YouTubers lose their minds.
YouTube science guy Tom Scott claims his newest video can be viewed in 2D and 3D at the same time, even though it wasn’t shot with any special equipment. What sort of dark magic is this? Well, as Scott explains, it all comes down to the Pulfrich effect, or a psychological interpretation where your eyes perceive motion as having depth due to a delay processing darker images from lighter ones.
Clear as mud, right? It will be once you try it yourself.
To view the clip in “3D,” just cover your right eye with dark sunglasses and view it with a fast, stable connection in a bright room (Note: it works much better on a laptop than a smartphone, and a slower connection may cause the frame rate to drop, nullifying the effect.).
Because your right eye sees a darker image, the signal it sends to your brain will be delayed by around one frame. The result of that delay is that you end up perceiving two distinct images, one from your left eye and one from your right. The final ingredient is motion. If the camera is stationary, both images would sit on top of each other and your eyes wouldn’t know the difference. However, once the camera starts panning, it’s as if you’re seeing two images from two cameras that are filming next to each other. It won’t look like Avatar, but it does work surprisingly well.
Modern 3D is different because it’s created by projecting two separate videos onto a screen and combining them with filters (in most cases, those goofy 3D polarized glasses). As Scott points out, his method has been used on the big screen in the past, like in the 1993 Doctor Who episode “Dimensions in Time,” but isn’t practical for everyday uses.
However, for viral YouTube videos, this fascinating method of simulating 3D is a real gem.