“This video is 2D and 3D Simultaneously: the Pulfrich Effect”

Tom Scott has created a brilliant demonstration video of the Pulfrich Effect. You’ll need a pair of ordinary dark glasses – use just one side to cover just the right eye. Then watch his video. You’ll see the video in full color 3D, event though it is a 2D video.

3D video enthusiasts may already know a bit about how this works. When a camera is panning across a scene, each frame records a “position” in time. We sometimes use this trick to convert a 2D video into a 3D video by recording in 2D, but then creating a separate left and right track with the tracks separated by a single frame from the original 2D recording. This creates a left image track – and a right image track – by taking advantage of the movement in the scene.

The technique works as long as either the camera is moving or one or more objects in the scene are moving laterally. It does not work if objects are moving vertically or if objects or the scene are stationary.

The Pulfrich Effect uses the same idea but incorporates the peculiar nature of our optic system. Specifically, our eyes process darkened images slightly slower than bright images. The darkened image seen through dark glasses covering one eye are processed with a delay of about 15 milliseconds which works out to about 1/60th of a second. (The actual processing delay depends on the actual darkness of the image and could be more or less.)

Tom’s Youtube channel is here. He’s always got fascinating topics and I encourage you to subscribe to his channel on Youtube.

Experiment: I suspect this works also for VR 3D. Take a VR 360 video but keep the camera slowly rotating during filming. Then, cover one eye with a dark glasses shade while watching the VR video using a VR set up. As long as the subject is slowly moving laterally, the 3D effect should be visible in 3D!

[The featured photo for this post is from Pixabay.]

 

 

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