Question: how do 3d movies work

Stephen Davitt answered on 15 Nov 2016:

So in order to understand how 3D movies work we need to think about how we see… we have two eyes which are separated, this means we have an image that our left eye records and an image that our right eye records. This is called stereoscopic vision.

Now as an exercise put your hands together to form a triangle and look at something far away through the triangle… one at a time close each eye and notice that the image you see is different it moves… Your brain sees this move but knows its the same thing, so it interprets it as just being further away.

Now onto the movies… when being recorder the 3D movies are recorded twice, two cameras are put side by side just like our eyes. These movies can then be played back on top of eachother to create a 3D movie, one movie for your right eye and one movie for your left eye.

But how do we not just see two movies? wont both eyes see both movies? And this is where the glasses come in, light travels in waves and as such the waves can be in different directions (up-down, left-right etc), we use polarisers which are optics that only let light travelling in one direction so for your left eye we play a mive in up-down direction and for your right eye we play a mive in the left-right direction, this means that if you put on 3D glasses with up-down and left-right lenses in them only one image will go to each eye.

So when we see the two images, one in each eye and there is a difference, our brain is tricked to think that just like in our stereoscopic vision that means the object is further away or closer, and this creates the 3D effect