HOW 3-D WORKS

Our eyes each see a slightly different view of the world.
Go to a window and hold a pencil up in front of your nose, about a foot from your face. Close your right eye and without moving the pencil, compare its position to that of a distant object like a tree. Then without moving the pencil, close the left eye and observe the same relative positions of the pencil and the tree. The result will look something like this. (Assume the letter "A" is the tree and the letter "i" is the pencil.)


Now the trick is to combine the two images and give the illusion of depth.
In the real world, its no problem - your brain does it for you.
But when the two images are on paper, or a computer screen, it's a little different.

HOW TO DO IT

PARALLEL Format
(Just focus behind the two pictures and fuse them together.) This takes practice.

TOP VIEW of the PARALLEL Format
LEFT image is on the LEFT.
Focus BEHIND the pair of pictures.

This format is called the PARALLEL Format. Notice how the pencil appears closer, and the tree farther away. This is the method I use (PARALLEL Format), but many people prefer other methods.

Parallel Format NO GLASSES - Focus BEHIND monitor and Fuse images together.
Try this from about 18 inches from the monitor until both "i"s or both "A"s fuse together.

PARALLEL PAIR FORMAT - Left image is on the left.

ANOTHER WAY TO DO IT

CROSS-EYED Format
(Just cross your eyes and fuse the pictures together.) This takes practice.

TOP VIEW of the CROSS-EYED Format
RIGHT image is on the LEFT.
Focus in FRONT of the pair of pictures

This format is called the CROSS-EYED Format. Notice how the pencil still appears closer, and the tree farther away.

Cross-Eyed Format NO GLASSES - Cross Eyes and Fuse images together.
Try this from about 6 to 12 inches from monitor until both "i"s or both "A"s fuse together.

CROSS-EYED PAIR FORMAT - The Right image is on the left.

DISADVANTAGES of NO GLASSES:
1) It requires practice.
2) It requires practice.
3) It requires practice.

requires that you cross your eyes to view the stereo pair.
requires parallel "free-viewing" for the stereo pair.

Neither approach is comfortable.

There are several optical and electro-optical ways to superimpose the images of a stereo pair. Several manufactures make different products to aide viewing. We can't list all the various methods, but here are a few choices.

1. A trial frame set can be configured with two 4 diopter base out prisms to help counter the normal tendency to converge on close images. Plus one diopter lens should be added to the frame for easier focusing. Of course these settings are just a starting point and you should adjust the values for comfortable viewing.

Several companies make mirror systems which divert your view to parallel and widen your gaze to allow comfortable viewing of larger images. This is usually comfortable and the larger images give you more detail.