Tuesday, November 25, 2008

Cross Eyed Stereoview

Cross Eyed Stereoview, often shortened to X-3D or just X3D, is a fantastic and rewarding way to look at specialized pairs of images in 3 dimensions, or 3D, right on a monitor or printed sheet of paper.

Since I will likely be including many stereoview images in my future posts, I wanted to provide a brief but fairly detailed tutorial on how to view these fantastic x-3d images yourself right on your monitor.

First I will provide a few very basic exercises for you to familiarize yourself with how to view an X-3D image. If you are already familiar with X-3D stereoview images and how to look at them there is little in the post for you. Please feel free to skip down to the end and view the marvelous sample images I've provided as part of this material. Feel free to read my tutorial and provide input if you would like.

Let's start with the simplest of simple practice exercises. Below are 2 letter "O"s between lines. All you have to do is look directly at the line between the "O"s and then start slowly crossing your eyes until the 2 "O"s seem to become one "O" between 2 lines. Depending on how your eyes and mind work you may see sort of semi transparent "O"s on either side of the lines. This is normal and you should try to ignore them, concentrating only on the central "O". If it is blurry keep looking at it and concentrate on it until it comes into focus. Don't let your eyes diverge, keep that center image crisp and sharp.


Okay! If you can do that, fantastic! All you have to do is do it again here. I've exaggerated the distance between the "O"s considerably. This will mean you'll have to cross your eyes a little farther in order to focus on the center "O". Go ahead and practice it now using the exact same methods as in the previous exercise.


Can you view the center "O" in that previous exercise clearly? If not just go back and keep trying. It's not too tricky and once you get the hang of how to do it this will become second nature to you, just like looking at a normal flat photograph. If you've got it then let's move on! Time to experience your first 3D effect from a very simple X-3D pair.

The 2 sides together are referred to as a pair. Every X-3D image will consist of a left image and a right image which are combined to make a pair. As long as paired images are aligned properly with an acceptable field of depth they will always create a sharp clear center image that you will see in 3D. So on with the next exercise.

This time there are several letters on each side. Again focus on that center line and begin crossing your eyes until all the "O"s appear to be on top of each other. The "O" in the right image is slightly out of spacing with the same "O" in the left image.


Have you managed to get those "O"s lined up? If you have notice something odd about the one in the middle? Does it appear to pop out of the screen at you a little bit compared to the letters on either side of it? If it does that superb! You've mastered viewing X-3D and are ready to start looking at some real image pairs! If not go back and look again, you'll get it, I'm sure of it.

I hope you're excited to view your first X-3D image. The image below is very complex with lots of spectacular detail for you to view in 3D, but at the same time should be very easy to line up by crossing your eyes because it has easy check points. So for this next exercise concentrate on the peak of the miniature snow pile in the pair and cross your eyes until it becomes one. Once you've merged the pair into one image you can start moving your eyes to look at other places in the image. Go slowly at first. If the image snaps out of place simple go back, focus on that peak again, align it, and try again. With a little practice you should be able to look all over the image just like a normal photograph, except now you're experiencing the photograph with depth perception! You should be able to see various clumps and flakes of snow in 3 dimensions. Take some time to practice with this image and enjoy the beauty of snow up close and personal.

View my original image on Panoramio.com -->

Once you're able to view the image clearly in X-3D go ahead and click on it to open the full size image. It will require you to cross your eyes even further, but you'll be rewarded with an even more in depth and detailed view!

Once you've mastered viewing the snow in X-3D here is a fantastic stereoview of a feature from the Antelope Canyon in the Navajo reservation near Page Arizona. This time you don't have a prominent contrast to easy focus on. Look at either side of the pair and find a feature that seems to stand out and use that as your focal point as you cross your eyes to view the pair. In this pair try using the darker underside of the sandstone near the center of the images on each side which contrasts nicely against the illuminated sandstone behind it.

Original Image Credits: The image on the left was taken by Seeher and the image on the right was taken by Michel Le Nouy. Please click each link to see the respective original photograph from their respective galleries. The 2 images have been resized, cropped, rotated, and had other signicient digital modifications to allow them to be paired as a new X-3D.

View my original image on Panoramio.com -->

After you've mastered this image go ahead and click it to view it full size. I hope you'll enjoy this one, it is one of my favorites!

Now that you've been able to focus on a fairly complex X-3D pair, it's time to go to the last stage, a pair with features parralax as well as perception of depth. That is to say you'll have to cross your eyes to a greater degree to see the closest parts of the image and to a lessor extent to see the farthest parts of the image and all varying degrees in between. This is very common in pairs created from aerial photography such as the follow pair I created from 2 photographs of the Rocky Mountains around Carbon Peak taken from a jet liner at 34,000 feet. Concentrate first on focusing on a central point such as a mountain peak.

View my original image on Panoramio.com -->

Once you've mastered viewing this small pair go ahead and click it to view it full size. Go ahead and take in the full splendor of how majestic the Rocky Mountains are in 3D! Now that you've mastered all the exercises in this tutorial you should be ready to view any well composed X-3D image you come across anywhere on the Internet or in printed material. They are very rewarding images to look at and really add a sense of depth perception and dimension to any scene!

Just as a final note because I learned this from my own experience when I started composing my own X-3D images: Not all pairs are properly spaced and aligned! If one image is out of synch with the other in any way it will make it more difficult, and sometimes impossible, to view the pair properly. Most X-3D composers use special programs to aid them in making sure their pairs are flawlessly aligned and spaced. I've used such applications on all the pairs shown in this tutorial.

Inconsistencies in pairs can include any or all of the following: scale, vertical shift, rotation, and barrel effect. Once you've become fluid with viewing X-3D images these flaws in pairs will become much more obvious to you when they are present.


Blaine said...
This comment has been removed by the author.
Blaine said...

I really love stereoview 3D pictures. It takes hard work to make good steroview 3D pictures.