Introduction
This page illustrates a simple technique to create and visualize stereoscopic (3D) pictures.
The principle is very simple. Stereoscopic perception is motly based on binocular vision, each eye seeing an image which is slightly different from the other, the viewpoint being shifted by about 7 cm (the average distance between the two eyes).To recreate the perception of depth, one only has to take two pictures, shifting positions between the exposures. Then one has to look at these two pictures simultaneously, making the right eye look at the right image and the left eye at the left image.
Left and right images. They are slightly different.
There are many ways to perform the trick, and I only focus on one technique here. It should be easy to use for anyone who's got a digital camera. The only other thing needed is a mirror.
Le principle is the following : first the "right" image is inverted through a vertical axis, as illustrated in the next image.
On the left, the original "right" image. On the right, the same image after a vertical symmetry inversion. This step can be performed with any picture manipulation software.
Then the "left" picture and the "right" picture are printed or displayed side-to-side on a screen. Finally the mirror is erected between the two picture, reflecting side towards the "right" image.
Démo
Then, each eye see only the image it should see. The left eye sees the left image directly, whereas the right eye sees an inverted version of the "right" image, which is fine as that image had been previously inverted!
Important remark about the choice of the mirror Mirrors which one can buy at supermarkets are not always of good quality. Most of yhen are designed/optimized to be used face-on. They may give two images when used as described above, one image coming from the silvered surface, the other from the glass that protects it. I found that when it is the case, turning the mirror in its own plane can help, one has to find the orientation of the mirror for which this side effect is minimal.
Try it on the following pictures. It is best to enlarge yout browser as much as you can.
stones in Hawaii
Orchidée
Let's play with images...
Looks like rotten bread !
cactii
Here is what you look like !
It works fine with synthetic images too.
Successive frames in movies can do the job too. From "The Rope" by Hitchcock.
Two other still frames, this time from "Chacun cherche son chat" by Cédric Klapisch.
Images of Saturn from the Fubble Space Telescope.
Images AS12-49-7318 et AS12-49-7319 from the Apollo 12 moon mission. I made some alterations to the original photographs, to enhance the stereo effect (resampling and contrast balance between the two images).