How Do 3D Movies Work?

5 centimeters: The average distance between your 2 eyes, and the reason why 3D vision is possible! Everyday, each of our eyes sees the world from a slightly different perspective. Our brain is designed to take full advantage of the two images it receives from our eyes to calculate the distance to an object, otherwise known as depth perception. This is how we judge how far the car stopped in front of us is, or how quickly a baseball is being pitched to us. Certainly having good vision in two eyes provides us with the best depth perception, but depth perception is still possible using only one eye. Your brain can also utilize the size of objects in your vision to determine how near or far they are. Buildings that are further from us appear smaller and those that are closer appear larger.

Everyday we live life in 3D (3 Dimensions). Movies however take place on a screen and are 2D (2 Dimensions). In order to create the illusion that we are on the set of a movie and that airplanes are literally flying overhead and cars are careening toward us, cinematography takes advantage of vision science and the brain! An earlier, more basic way of creating 3D movies was to utilize color. The viewer wears special glasses whereby each lens is a different color: Red and Green or Red and Blue. This technique, however, does not allow the viewer to see the true colors in a film.

The newer, more common approach to 3D cinema is through the use of polarization. This is done by using polarized lenses to show each eye a different movie at the same time! 2 movie projectors project 2 movies onto the same screen, each movie with different polarization. Moviegoers wear special glasses where one eye sees waves of light traveling along one meridian and the other eye sees waves of light traveling along another meridian 90 degrees away or perpendicular to the other eye. 3D movies shown in theaters and theme parks utilize polarization.

Lastly a more expensive option, which requires specialized equipment, uses LCD glasses to show 2 images in rapid succession, one to each eye, while the alternate eye is occluded. Televisions capable of 3D programming utilize this technology.

So what if you’re a moviegoer with only one eye or a lazy (amblyopic) eye that doesn’t participate in your vision? Can you appreciate 3D in a 3D movie? The answer is “no.” To appreciate 3 dimensions in a movie, your brain has to receive input from 2 eyes. This holds true for viewers with contacts or LASIK surgery whereby one eye is focused for reading and the other is focused for distance vision (monovision). For viewers who have the option, to truly reap the benefits of the extra $5 spent to see Spiderman flying toward your bucket of popcorn, wear glasses or contacts that allow you to use both eyes for distance viewing.

Enjoy the show!

If you have questions about your vision or are in need of eye care in Wellington or new glasses and contacts, give our office a call!

Amanda Weiss, OD
SeaView Eyecare


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