stereoscopic 3D

WHAT IS STEREOSCOPIC 3D?

So sometimes it is best just to start at the beginning. We like to do this at Made Visual Studio as often as possible. And we’re going to do the same here.

Essentially stereoscopic 3D (S3D) is the illusion of depth in a two dimensional image. And it is an illusion. It involves presenting two images of the same subject, each from a different position, then tricking the brain into merging these into one.

The ‘trick’ happens by showing each eye a different image, which is where the glasses come in but more about this shortly.

You can illustrate this for yourself by simply holding a finger a few inches from your face and closing each eye alternately while looking at the finger. You’ll notice that the angle from which you’re viewing the finger changes and that you can see different parts of the finger depending on which eye is open. In a sense you are seeing two different images of the finger.

When you view the finger with both eyes you are still seeing two images but your brain makes one image. This allows your brain to understand that the object has depth.


Views of an object from each eye
In S3D we use the same trick. We take two cameras and present the same scene or object from different angles. Using the glasses we can control which camera footage is presented to which eye and your brain does the rest, merging both sets of footage into one.

So this is the simple bit. It is easy and I imagine that everyone here knows this.

Where S3D gets interesting is in learning how to manipulate these images on screen for creative effect. How do you make objects appear as though they are coming out of the screen towards you or make the actor appear to be in front of an object?

Simply put, your mind has a number of depth cues. These are signs that tell the brain that there is a measurable distance between objects. These have been manipulated by filmmakers for years. Focus is the easiest to understand. If something is in focus and the objects around it are out of focus then your brain can understand that there is a distance between these objects.


Graham in focus but background is otherwise
There are eight depth cues in total and the two angle/finger example that we looked at earlier is referred to a stereopsis. By altering the distance between each image we can control how far forwards and backwards they appear to be. If we move images closer together on screen it forces your eyes to focus as though they are closer, while if we move these images further apart your eyes focus as though they’ve become further away. Too much manipulation either way and the viewing experience becomes very uncomfortable.

source: http://www.projectchapman3d.com/blog/?p=73