Some of us have been to see 3D movies at the cinema and been utterly blown away. Some of us have come away from these experiences and wondered just how on earth that mind blowing effect was created.
This is how its done.
We see with our eyes, both of them. Our left eye sees its perspective on things as does the right eye. Both eyes are looking at the same thing at the same time but from ever so slightly different places, about 2.5 inches. Our brain then takes these two images from each of our eyes and builds what appears to be 1 image. This is what we see, and its about as 3D as its going to get. Its the image that makes us feel like we are where we are, totally immersed.
Its pretty much the same at the Movies.
These Movies are actually filmed with 2 cameras at the same time, roughly 2 to 3 inches apart, exactly like our eyes looking at something at the same time. So, because our 3D Movie is filmed with 2 cameras we end up with 2 films, one filmed from the left camera and one from the right, each has its own very slightly different perspective on the subject.
So to create the effect that we see with our own eyes, these 2 movies need to somehow be played at the same time on the same screen. This is the clever bit. We ARE actually watching 2 movies at the same time!
This is why we need to wear 3D glasses at the Movies. They have a special filter on each eye that lets the left eye see what the left camera saw and the right eye see what the right camera saw. As these 2 movies are playing at the same time, the glasses interpolate which side you need to see with which eye.
The end result is your brain sees one image that looks 3D.