November 4th, 2009 by bobble
A couple of years ago I got into making stereograms. I saw it in a how-to book and thought that it was pretty cool! I didn’t realize just how easy it is to create stereograms. All you have to do is take two photos about 3-inches apart and use software to merge the right/left images together.
Cross your eyes to view it.
Taking the Photos
with a single camera, you are limited to taking static pictures. There can’t be any moving objects; cars, blowing trees, flying mommy-bombs, etc. if you look closely in the above stereogram, something had moved near the foundry. It was a windy day. It creates a double image which you don’t notice right away but then try focusing on it.
Get about 6-8 feet from your subject and take one picture. Shift your hips to the left or right a couple inches while keeping the camera steady. Keep the lens parallel to the first shot. Take the second picture.
One In Thirty Rule
the distance you move, or lens separation, is called the stereo-base. In order to take decent stereo photos, distance to the nearest subject should be approximately 30 times the stereo-base distance. This is called the “one-in-thirty rule”. Our eyes are about 3 inches apart. This would mean that the nearest subject should be roughly 8 feet away.
I use Stereo Photo Maker (click here) to create stereograms. It has functions to help correct alignment problems. Almost every stereo pair I’ve taken has alignment issues. I might’ve tilted the camera or moved it vertically too much from the first snapshot. This software will help make it more goodly. I’ve built a tripod mount for sliding a camera back and forth. I found that just shifting your hips, keeping the camera steady, and using this software is good enough… you won’t notice the difference.
Viewing Stereograms Without a Viewer
Bobble no like anaglyph 3D pictures. It’s those 3D pictures where you need red/cyan glasses to view them. The colors get all messed up. I prefer “freeviewing” without glasses or viewer. There are two ways of freeviewing stereograms. It depends on how the images were joined together. If the right eye image is on left-hand side of the stereogram then you need to cross your eyes to view the image. The size of the photos are quite large, I think its best to use cross-eyed viewing.
If the right eye image is on the right-hand side of the stereogram, then you don’t cross your eyes. You stare past or through the plane of the image. When you do this correctly each eye will see its intended image. This is called parallel viewing and for some people it’s a little harder to master.
In both methods you’ll end up seeing a third image that appears between the two photos (called the cyclopean image). That’s where you focus your attention. Eventually your brain locks in on this virtual image and then things start to stand out.
Some people have difficulty seeing 3d stereograms. It’s not unheard of for people to get headaches. I recently ran into my own problems and had an eye cataract removed. Now the only way I can freeview is if I’m wearing a contact lens in my good eye and wearing reading glasses. Sucks to be me.
What’s strange is if you accidentally swap the images or cross your eyes at a stereogram that is meant for parallel viewing. The cyclopean view looks 3d-ish but in a weird way like the image is inside out. When in doubt, try parallel and cross-eyed viewing to see what looks correct.
when taking stereograms photos:
* Everything in the picture should be in focus.
* The depth of focus should be large as possible.
* Avoid dark backgrounds
* Avoid excessive moving subjects like blowing trees or clouds.
* Follow the one-in-thirty rule.
* Keep the cameras level to the ground. Avoid tilting.
Stereo Camera Rig in Stereo!
Another cross-eyed stereogram. It’s a little easier if you have two cameras and rigged them with a dual trigger mechanism. Yes? Yes!
Dig the BMX bike peg for the handle! And toggle switches!?!