LEARN 3D-VISION  using cross-eyed or parallel techniques. 

(created 20010327)

See first the NOTE from Morgan Wright, optometrist, about 3D vision

Introduction : three-dimensional vision enables you to see in 3D from a set of two normal pictures taken with future 3D display on mind. This unaided stereovision is accomplished through one of two techniques  : cross-eyed (CREY) or parallel (//). The CREY vision is the more powerful as it permits unlimited size of images but maybe more difficult to learn ! The // vision is limited to small pictures as the distance between the center of the pictures must be the same as the distance between your eyes; but it is not tiring at all as each eye just look straight forward  even for a beginner !

Making/placing the originals 3D pictures : The photographer select an appropriate subject with different depth planes. He takes the first picture carefully centering the field on a particular detail, then translate the camera horizontally to the right (or left but always keep the same to simplify later processing) and takes the second one also carefully centered on the previous detail taking care not to rotate the camera (at least much). For good 3D effect the distance between the two shots is at least 5% of the distance of the main subject. As soon as you see a visible difference in your view between the two position, it's Ok !  The more distance in between pictures, the more 3D effect ... but exageration turns out very bad and hard looking at images. Minor problems can be fixed later while processing images. For display, the image to be seen with the left eye is put on the right and reciprocally (CREY) or at their standard place (//). If you face one style of image you can modify it to the other technique by inverting the right & left pictures.  If you make a mistake and invert the images, the 3D effect will apply but reversed (fi.: a ball will look hollow !). You may have to shrink the images for // 3D vision. Recently I discover that vertical images can be larger than horizontal ones due to screen configuration (see gallery) !

Practically for most images  at relatively short distances (up to 50m) : I stand facing object with both legs at the same level, 1 meter apart and feet at ~90° angle. I bend (more or less depending of the amount of distance I want to create in between pictures) my left leg, center a detail somewhere on the middle vertical line of the screen, verify horizontality and take the first picture. Then I bend the other leg of the same amount, center the same detail at the same place as first picture, verify horizontality and take the second one. Using a bubble level on the camera would be nice (just got this idea rigth now !).

For more distant scenery, just be sure both pictures are taken at the same horizontal level.

If you take people as them to stay as "statues" !  
For other living creatures (animals, trees, flowers) be sure no movement has occured in between (avoid wind, separate clouds can change lightning...) !

The lessons : Some people learn this technique in an instant, some have incredible difficulties. My project here is to make everybody succeed. This is why I made thoses illustrated lessons to help the formers.  Your numerous mails give me encouragment & new ideas ! Each lesson is on the same page, so when it is entirely loaded, you may disconnect your computer from the phone line. As learning to ride a bicycle for the first time it is tiring and prone to failure. So please to avoid eye ache, limit your first tests to about 5 min, relax by closing your eyes a few seconds between trials. Don't be discouraged if you fail today ! You can retry tomorrow (you can print the pages !). After a while it becomes almost as easy as normal vision ... and as bicycle riding, you will never forget !

Then, you can also, for fun, look with a 3D-vision at your keyboard, some repetitive screen saver & other sceneries in your life ...

When you will succeed in 3D unaided vision, to know which technique your brain is using at any moment, move your head sideways. If the images moves in the same direction as your body, you are using cross-eyed vision. If directions are opposite you are using parallel vision.

Now GOTO cross-eyed (CREY most used in this site) or parallel (//) lesson !

A book of reference for superb pictures & with which I really learned 3D vision :

SUPERSTEREOGRAM, Cadence Books, 1994
Cadence Books, A division of Viz Communications Inc,
P.O. Box 77010
San Francisco, CA 94107


(Courtoisy Morgan Wright, Optometrist)

I am an optometrist (eye doctor) and should give you the following advice about 3D vision.

1. You should tell people that before they can see in stereoscopic 3D, they have to have two good eyes and no lazy eye (amblyopia) because some people cannot see in stereo, and will get upset if they try, the will never see it. If they have an eye that turns in or out, or one eye with poor vision, it won't work.

2. People over 40 years old will need to use reading glasses before they can see 3D.

3. Even for young people who can focus up close without reading glasses, the technique where you make your eyes go parallel (you call the parallel technique) forces you to relax the focus of your eyes, and many people will see fuzzy if they don't use reading glasses before they try this. People who are nearsighted (myopia) should remove their glasses before trying this so they can see close without focusing their eyes. For people who are farsighted (hyperopia) I recommend reading glasses for this technique.

4. As for the cross-eyes CLAY technique, young people won't need reading glasses for this because the focusing mechanism is working when you cross your eyes.

A final note : when looking at 3D images in the gallery, you can just scroll the screen with the elevators without returning to normal vision in between images !
Next step would be a 3D movie  :)

Reminder :

Texts and images of this web site all Copyright S. Weiller, 1998-2010