SAYLOR3D

Are you viewing 3d stereoscopic images for the first time?

If so, it may take a little practice (and patience). It has been compared to riding a bicycle. It may take a little time at the beginning to learn the technique but the reward is well worth the effort.

How does stereoscopic vision work?

In everyday life, your eyes capture two images of every scene. These two images are separated by a little over 2 inches. The brain combines these two images and the results are a stereoscopic 3d scene with depth.

With photos, two images are also necessary for your brain to see stereoscopically. Contrary to a first impression, the photos are NOT identical. One photo is for the left eye and one photo for the right eye.

The photos were taken from two separate positions. When viewed properly, the brain will create a 3d stereo image from these two photos. You will see the image as if you were looking through a window. It will no longer be flat but will have depth as a real scene would.

When using two cameras, they are usually spaced the same distance apart as your eyes. However, different camera spacing distances can be used to achieve a desired result. Since the eyes are fairly close together, anything beyond about 100 meters will look the same when observed with one eye or two eyes. There will not be enough difference in the two views to create an effect of depth. By placing the cameras farther apart and taking the photos, there will be enough separation in the scene for stereoscopic viewing. By placing the cameras closer together, you can also capture great stereoscopic closeups.

3d stereo photos on the web are generally presented in either parallel or cross-eyed format. With parallel (or free view) images, the left image is for the left eye and the right image is for the right eye. With cross-eyed view images, the left image is for the right eye and the right image is for the left eye. Cross-eyed format seems to be the most popular way to display images on the internet since most people are already familiar with how to cross their eyes. However, in my opinion, parallel viewing is easier on the eye muscles as the displayed photo size gets larger.

When viewing parallel images, the aim of the eyes must diverge as if you are looking at a scene far away. This is what generally happens when you daydream and the muscles that control the eyes relax.

When viewing cross-eye images, the aim must converge as if you are viewing something very close. This happens when you look at a pencil in front of you and you bring it closer and closer to your face.

Magic eye and random dot stereograms are popular examples of parallel view images.

So, how do you actually learn these skills?

Shown below is Image #1. It can be used for either Parallel or Cross-eyed viewing.

The image consists of two white boxes that contain a gray pole, two blue circles and a red circle. These items are not placed the same in the left and right squares. The gray pole is in the center of both, but the red circle is not directly above the pole. (The blue circles are placed differently too!)

Image #2 is a representation of what you will see when you are viewing image #1 correctly. The squares are identical in this image. It has no depth effect. It is just to show you what you will see with image #1.

Method for Parallel or Free View

By allowing your eyes to relax as if you are daydreaming or looking off into the distance, Image #1 can be made to appear similar to Image #2. It will not be identical, the spacing between squares and shading of the two outside squares will be different. When you achieve the proper effect, the center image will be 3d. You should ignore the left and right images.

Initially, Don’t focus on the screen. Instead, let your eyes unfocus. Stare past Image #1 as if looking far away. When you see three squares you then change your focus to the square in the middle.

Some find it helpful to look at an object across the room and, without focusing on the screen, turn back to the screen until you see the images. Only when you see three squares do you let the eyes focus on the middle square.

If your screen is not directly in front of a wall, you may look over the top of the screen to achieve the same effect. As you bring your eyes down only focus on the middle square when you see three squares in Image #1.

Method for Cross-eyed viewing

This one, for most people, is easier to accomplish.

If you can recall how you did it as a kid, just cross your eyes gently and focus on the middle square.

Otherwise, hold your finger near the screen. Start with it just underneath the left square of Image #1. Now, move it to the right so it is between the squares but still below them so as not to cover any images. Bring your finger slowly toward your face. Keep your focus on your finger! When you see an image just above and past your fingertip, transfer you focus to that square.

What you should see

If seen in the parallel view, the red circle is the farthest away. The blue circles are between the red circle and the pole.

If viewed cross-eyed, the red circle is closer and the gray pole is the farthest away.

These are small images and the dept effect is not great.