Small dark seeds in a spiral head

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rjlittlefield
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Post by rjlittlefield »

MacroLuv wrote:Interestingly, while trying to cross my eyes I got another illusion - two photographs does not look parallel but forming an angle like "V".
Very observant! That happens to me if I go very cross-eyed and for whatever reason don't get the images fused. I think it's due to minor muscle imbalance that causes the eyeballs to rotate slightly unless they get feedback from the brain telling them not to do that.

(Many years ago in college, I had a crazy work schedule that made me stay awake for 34 hours straight, then put me a physics class at 8:30 am. I would know that I was about to fall asleep, when the blackboard would suddenly appear to clone itself, and the two copies would rotate inward as if to spill the professor's writings onto the floor. But I digress...)

I speculate that your eyes are doing exactly what they are normally supposed to do: converge and focus at the same time onto the same point. Unfortunately, with crossed eye stereo, that normally correct behavior becomes a problem. When you converge enough to properly overlap the two images, the focus shift can make them so fuzzy that they never fuse properly. Ironically, young flexible eyes will have more trouble with this than old stiff eyes (see "presbyopia").

To get around this problem, you have to somehow break the connection between convergence and focus. But I have no more ideas at the moment about how to accomplish this. Sorry!

Perhaps someone of our other binocular stereo people can chime in with new ideas? :?

--Rik

cactuspic
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Post by cactuspic »

Now you did it Rik. Not only do I find I can't cross my eyes correctly, but I learned half my brain is deficient and I need to eat more protein. Thanks.

Good post. I like the seed shot but I do have trouble getting the stereo view. All I got was a headache. I will try again tommorrow with a fresh set of eyes.

Irwin

MacroLuv
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Post by MacroLuv »

Besides an angle "V" illusion I could swear (If I don't know it is impossible because of barrier position) that I'm looking at left picture with left eye and on right picture with right eye! :shock:
The meaning of beauty is in sharing with others.

P.S.
Noticing of my "a" and "the" and other grammar
errors are welcome. :D

rgknief
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Re: Small dark seeds in a spiral head

Post by rgknief »

Thanks for the post.

I've tried to view a crosseyed image here for over a year. It used to come naturally, almost instantly.

This is the first crosseyed image I've been able to "bring together" completely. One problem: I see it as a negative, like looking down into a cavity. I was able to see the parallel image immediatley after with no difficulty. I saw it as the positive stereo as designed.

The bigger images still don't come together, even though I'm on a 3200x1800 laptop display, but it was sure nice to see stereo again. The "find the hidden stereo object" pictures normally do not cause me any problems.

rjlittlefield
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Re: Small dark seeds in a spiral head

Post by rjlittlefield »

rgknief wrote:
Tue Oct 25, 2022 10:16 am
I've tried to view a crosseyed image here for over a year. It used to come naturally, almost instantly.

This is the first crosseyed image I've been able to "bring together" completely. One problem: I see it as a negative, like looking down into a cavity. I was able to see the parallel image immediatley after with no difficulty. I saw it as the positive stereo as designed.
Seeing the crossed pair as a cavity means that you have fused the crossed pair as parallel.

Apparently you are no longer able to voluntarily force crossed fusion.

Probably this is just a matter of being out of practice, though of course there can be physiological reasons also.

If your vision is working fine for normal purposes, and you can also view parallel OK, then I suggest to use a piece of software that can swap left/right so as to convert crossed to parallel. The most full-featured program that I know for that is StereoPhoto Maker (https://stereo.jpn.org/eng/stphmkr/). If you have Zerene Stacker, then recent builds of that can also display stereo and swap sides easily by using Tools > Stereo > View Existing Stereo Pair > From Input File and pressing the Swap Sides button. You can load the image pair directly from the web by getting the image URL from your browser via rightclick > Copy Image Address, then in Zerene Stacker do a File > Add File(s) and paste the URL into the "Object name" field of the file chooser panel.

--Rik

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