Fotoartist Loc: Detroit, Michigan

I saw all your anaglyphs posted. What is the amount that you throw each red and cyan image off center?

selmslie Loc: Fernandina Beach, FL, USA

That is interesting.

Clearly you are referring to a different "cross-eyed" technique than the one that has been presented here elsewhere on UHH. Those images are very small (usually less than 1000 pixels on a side) and they can only be viewed at close range. They are also generated by placing a distorted image (the right eye view) next to the original (left eye view) to be viewed with parallel gaze or cross-eyed. It's the arbitrary distortion of the right eye image that destroys any 3D effect and makes it difficult or impossible to properly see the 3D.

Since you are starting with two frames, your approach is totally different. Neither image is distorted. It just represents two viewpoints. Your images can easily be presented as legitimate 3D either way using anaglyph merges or as separate images next to each other.

I am interested to know how large you make each of the images in your pairs. Larger images can, of course, provide a lot more detail and they can be viewed from a greater distance. This can reduce the problem of severely crossing our eyes while looking at a small pair close up.

I have seen 3D aerial map images taken from airplanes using a stereo viewer. The viewer eliminates the eyestrain and the print size is unlimited although you can never really see the entire image at once.

selmslie Loc: Fernandina Beach, FL, USA

In any superimposed pair of images there is normally one plane (camera-subject distance) where the two images are in register. There is no offset between the red and cyan images, no red or cyan fringe.

Parts of the scene beyond that subject distance are offset laterally - the red image is to the left of the cyan image.

Parts of the scene closer to the camera are offset in the other direction - the red image is to the right of the cyan image.

Download the image at 3D anaglyph - View under house, zoom in and you will see how this works.

Guyserman Loc: Benton, AR

Many years ago before digital I made shots by moving the camera sideways for two perspectives. Instead of mounting them to view cross-eyed, I mounted them to view parallel. I was planning to get a stereo viewer but before I located one I learned to relax my eyes and get the 3D perception so I never got a viewer. I really enjoyed it and built up a good sized collection. The images appeared sharper, clearer and more colorful than the anaglyph images I have seen since. Unfortunately, somewhere in the four moves I have made over the last 49 years, the prints got left behind.

Fotoartist Loc: Detroit, Michigan

I did and I don't see what you are talking about. I never heard that the red and cyan shift sides before and never saw that. Now I am confused.

shellridge

selmslie:

I don't understand the technique you describe in your first paragraph, but probably it doesn't matter. I acquire two shots that could each stand on their own and of course are very similar. This stereo pair could be viewed various ways, with a viewer, as an anaglyph, by polarized projection as seen in movies, or without any hardware by looking at one image with one eye and the other with the other. If the right eye looks at the image made with the camera lens on the right side, the size of the individual images is limited to the distance between your eyes. The wetware controlling the direction our eyes point has a pretty hard limit preventing them from going wall-eyed. But if the right eye looks at the left image and the left eye the right there is no limit to the size of the individual images. On a single computer screen the practical limit each image is obviously half the screen. For printed images there is no limit to how large they can be. I have printed pairs each 8"x10", but there would be no problem with making them mural size. Except for the fact that few people will be able to see the lovely 3D effect, of course.

Getting away from photography for a moment, the cross-eyed fusing technique is useful for comparing things. In high school at a summer job soldering circuit boards I would hold a correctly built one next to a new one and fuse them as though they were stereo images, to check that the diodes were in the right way around. Another real example is the comparison of printed pages of two nearly identical versions of computer programs. This way one effectively has to examine only one thing instead of looking back and forth. Where there is a discrepancy the detail seems to flicker because the brain can't complete the fusion properly. If you try this on periodic wallpaper you may notice that the true period is twice what you would guess. Then there are those puzzles in the Sunday paper: "Find six differences between these pictures ..."

selmslie Loc: Fernandina Beach, FL, USA

Take a look at the shadow of the railing in this image.

While you are looking at that image with anaglyph glasses your eyes will naturally move to merge the images. It's the slight shift in crossing and uncrossing your eyes that allows your brain to interpret the 3D.

If you blow up the image you might see that I superimposed the red and cyan images so that the plane of the lamp post is in register.

selmslie Loc: Fernandina Beach, FL, USA

See also 3D anaglyph - How critical is image alignment?