stereo vision and novel uses
Sep. 6th, 2010 08:09 am![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
miriam_eAs a child I was always interested in 3D stereo pictures, and collected many. I still have them.
Some were embedded under rippled plastic so that the stereo images lay in hundreds of thin strips side-by-side. The ripples above them bent the light from each strip out to one eye or the other, giving the illusion of a single 3D image composed from the two sliced images.
I have some other 3D pictures which are normal images placed side-by-side, but with one reversed. To view these you needed to put a mirror between your eyes at right-angles to the plane the images were on. Looking with one eye at the reflected image appeared to overlay it on the other image seen directly with the other eye, giving an illusion of a single 3D image. The advantage of this system is that you could have quite large 3D images. The disadvantages were that one must be reversed and that a mirror was needed for viewing.
My favorite 3D pictures were always the ordinary stereo pictures placed side-by side. I used to have a stereo viewer, which was a pair of magnifying glasses, one for each eye, mounted on a rack the right distance from another rack holding the stereo images. Of course, plastic toys break after years of use, no matter how careful the child is. Mine did too. That didn't stop me using the stereo pictures though. Understanding how the images work, I practiced making the line of sight from each eye go parallel by looking past the pictures to the far horizon, noticing at the same time, that the pictures would seem to separate into four images (double vision of two images), the center two gradually sliding together as one. This center image was the one I was interested in. It took a long time, but I gradually developed the ability to focus nearby while making my eyes look as if into the distance, so that the center image would snap together into a sharp 3D image without any external aids at all! This was exhilarating. I still get a blast out of it. The disadvantage of this technique is that only small images can be viewed, because similar points in the two images can only be separated by the distance between my eyes. Any greater and my eyes would have to diverge from parallel, and even with all my practice I found this almost impossible.
A way of viewing larger stereo pairs came to me one day when I was still young. I could swap the images over, so that the left image was on the right, and the right image on the left. Now instead of looking parallel, as if to the horizon, I needed to slightly cross my eyes, as if looking at a point halfway between my eyes and the stereo pair of images. To my utter delight this worked! This opened the way to viewing much larger images.
For many years I would return to the quiet and awe-inspiring worlds of my 3D images. I still do occasionally. However I don't just use this for looking at 3D pictures anymore. I have developed a number of unusual uses for this ability. Nowadays I use it mostly for quickly checking lists. I know there are computer commands that can be used to check the difference between two lists, but I find arranging the two lists side-by-side on the screen and using one eye to look at one, and the other eye to look at the other image is much more convenient and faster. Quickly looking down a list like this, I don't need to read the items, but can see instantly where the lists differ because the points that don't match seem to shimmer and look garbled. I use this technique almost daily and it saves me a lot of time.
Another trivial, but fun use is to view those magazine puzzles that show two images side by side that differ in tiny ways. Using this technique of looking at one picture with one eye and the other with the other eye, all the differences stand out instantly -- it feels a little like cheating though.
Yet another silly use is whenever I see closeup photos in magazines of people wearing sunglasses I like to merge the images from each lens this way and I can sometimes see the reflected world in 3D, occasionally even seeing the photographer.
What a wonderful computer we have in our skulls, and how marvelous are some of its uses.
Some were embedded under rippled plastic so that the stereo images lay in hundreds of thin strips side-by-side. The ripples above them bent the light from each strip out to one eye or the other, giving the illusion of a single 3D image composed from the two sliced images.
I have some other 3D pictures which are normal images placed side-by-side, but with one reversed. To view these you needed to put a mirror between your eyes at right-angles to the plane the images were on. Looking with one eye at the reflected image appeared to overlay it on the other image seen directly with the other eye, giving an illusion of a single 3D image. The advantage of this system is that you could have quite large 3D images. The disadvantages were that one must be reversed and that a mirror was needed for viewing.
My favorite 3D pictures were always the ordinary stereo pictures placed side-by side. I used to have a stereo viewer, which was a pair of magnifying glasses, one for each eye, mounted on a rack the right distance from another rack holding the stereo images. Of course, plastic toys break after years of use, no matter how careful the child is. Mine did too. That didn't stop me using the stereo pictures though. Understanding how the images work, I practiced making the line of sight from each eye go parallel by looking past the pictures to the far horizon, noticing at the same time, that the pictures would seem to separate into four images (double vision of two images), the center two gradually sliding together as one. This center image was the one I was interested in. It took a long time, but I gradually developed the ability to focus nearby while making my eyes look as if into the distance, so that the center image would snap together into a sharp 3D image without any external aids at all! This was exhilarating. I still get a blast out of it. The disadvantage of this technique is that only small images can be viewed, because similar points in the two images can only be separated by the distance between my eyes. Any greater and my eyes would have to diverge from parallel, and even with all my practice I found this almost impossible.
A way of viewing larger stereo pairs came to me one day when I was still young. I could swap the images over, so that the left image was on the right, and the right image on the left. Now instead of looking parallel, as if to the horizon, I needed to slightly cross my eyes, as if looking at a point halfway between my eyes and the stereo pair of images. To my utter delight this worked! This opened the way to viewing much larger images.
For many years I would return to the quiet and awe-inspiring worlds of my 3D images. I still do occasionally. However I don't just use this for looking at 3D pictures anymore. I have developed a number of unusual uses for this ability. Nowadays I use it mostly for quickly checking lists. I know there are computer commands that can be used to check the difference between two lists, but I find arranging the two lists side-by-side on the screen and using one eye to look at one, and the other eye to look at the other image is much more convenient and faster. Quickly looking down a list like this, I don't need to read the items, but can see instantly where the lists differ because the points that don't match seem to shimmer and look garbled. I use this technique almost daily and it saves me a lot of time.
Another trivial, but fun use is to view those magazine puzzles that show two images side by side that differ in tiny ways. Using this technique of looking at one picture with one eye and the other with the other eye, all the differences stand out instantly -- it feels a little like cheating though.
Yet another silly use is whenever I see closeup photos in magazines of people wearing sunglasses I like to merge the images from each lens this way and I can sometimes see the reflected world in 3D, occasionally even seeing the photographer.
What a wonderful computer we have in our skulls, and how marvelous are some of its uses.