Small dark seeds in a spiral head

[rjlittlefield]

These belong to some small legume that grows as a weed along my back fence. I don't know exactly what it is, but it reminds me of a teeny tiny alfalfa plant with yellow flowers.

Anyway, the seeds have always struck me as having interesting shapes and textures. I've never taken time to photograph them before, but with a free day and a few plants hanging on even after the ice and snow...



It's hard to tell from the picture above, but the seeds are arranged in sort of a spiral or an irregular series of whorls that go up the stem. The darker seeds are a bit older and closer to the base; the lighter ones are younger and closer to the tip.

If you can see stereo, you might like one or the other of the following pairs.



Hope you enjoy!

--Rik

PS. I'll think up some small award for anybody who's good enough to see stereo and switch fluidly between the crossed eye and parallel view versions. I can fuse 'em both, but switching between them was incredibly difficult until I spent about 5 minutes practicing just that. It's much harder than "rubbing your belly and patting your head, and then switching hands"!

Technical: Canon 300D with Olympus 80 mm bellows macro lens at f/8. Halogen dual-fiber illuminator illuminator with Whiffleball diffuser. Stacked by Helicon Focus from 0.010" focus steps.

Edit: to more carefully describe the pattern of seeds on the stem.

[JoanYoung]

You got me on this one Rik. I can't seem to get my eyes to go crossed eyed enough!! This plant look similar to a wild creeper we have here. The seeds are black and oval coming to a sharp point at the bottom. As kids we used to put the seeds under our tongues and wait for them to pop open which took a minute or two.

[Ken Ramos]

I find the two smaller images much easier to visualize in stereo than the larger two at the top and yes I did have a bit of difficulty switching between the two. The blue background really makes it or them, easier to visualize also.

[rjlittlefield]

Joan, try this:

Take your hands off the keyboard and back slowly away from the monitor!

Um, no, that's not really a threat, it just sounds like one.

The real point is that the farther you back away from the monitor, the less your eyes will have to cross, to fuse the images. After you get them fused, you can train your eyes by slowly moving closer.

I tried rendering this pair as a rocking animation, but it didn't work well enough to be worth posting out. All it showed was the very largest 3D structure -- that there's a thick lump of stuff that comes forward at top left and backward at bottom right. All of the fine structure, about which seeds are in front and how they are oriented, did not show up at all. Very disappointing!

I suppose I could put it out as red/cyan. Anybody out there with the required glasses?

--Rik

[JoanYoung]

Joan, try this: Quote:
Take your hands off the keyboard and back slowly away from the monitor!

Um, no, that's not really a threat, it just sounds like one.

You sure?? LOL!! Just kidding. Nope...I guess I was just not born to be cross eyed. LOL!! I was never good with these kinds of things (or 3D).... not enough practice at pulling faces as a child I suspect. But I will keep on coming back to this and practice.

[rjlittlefield]

Joan, there are a couple of possibilities.

Something like 10% of people just don't perceive stereo, meaning that even with natural scenes they can't determine depth without moving their heads. It's surprisingly common, even among people who see fine with both eyes.

The other 90% see stereo just fine under natural circumstances, but what I'm doing with these photos is anything but natural!

Under natural circumstances, your eyes see distant things by looking straight ahead (parallel viewing) and close-up things by converging (crossed eye). The amount of convergence required to fuse my crossed eye pair is not huge -- on my monitor, at comfortable viewing distance, it's about the same convergence as to look at an ordinary object at about 6 inches.

The problem is -- and it's a big problem -- under natural circumstances convergence is intimately tied to focus. Your brain has learned through long experience that when your eyes are parallel, your lenses should focus for infinity, and when your eyes are converged on a subject at 6 inches, your lenses should focus for 6 inches.

But that is not the case with these images. To properly see the crossed eye pair, one has to converge as if for 6 inches, but focus as if for 18 inches. Likewise, to properly see the parallel view pair, one has to converge for infinity, but focus for 18 inches. Breaking that connection between convergence and focus is "just" a matter of training, but for some people the training can be difficut. I did my basic crossed-eye training over 25 years ago so it's easy now, but I still remember that it was challenging at the beginning.

If you are modestly nearsighted, say requiring a -2 diopter correction, then odds are it will help to take off your glasses and look at the parallel view. In that case, your eyes will automatically focus at 1/2 meter (the reciprocal of your correction) when they are pointed straight ahead as if looking at infinity through your glasses.

You may be able to assist the fusion process by starting with your face very close to the screen, so that the images are very fuzzy but each eye unavoidably sees only one. Then back up very slowly, giving your eyes time to keep the images aligned while gradually bringing the screen into focus.

On the other hand, you could just decide that all this stereo stuff is way too much trouble, and spend your limited time doing something more valuable! I promise I won't feel bad if that's the case.

--Rik

[rjlittlefield]

I find the two smaller images much easier to visualize in stereo than the larger two at the top and yes I did have a bit of difficulty switching between the two. The blue background really makes it or them, easier to visualize also.

Interesting. It's the opposite for me -- I prefer crossed eye to parallel.

I think most of that is just available resolution. Without some sort of viewer, images for parallel view can only be as big as the distance between your eyes, since most people cannot diverge. That's only about 2 inches -- not many pixels to play with. On the other hand, with crossed-eye the images can be almost 1/2 width on the screen.

Actually I've gone as far as using two 1600x1200 monitors side by side. That was fun, but very difficult to share. I finally had to modify a Wheatstone viewer to let other people see what I thought was so cool.

I have to confess, the blue is for aesthetics. I shot first with a neutral gray background, and the result looked, well..."blah" would be a compliment. But a couple of pieces of paper through the inkjet printer, and voila, color!

I also have to confess that I messed up the lighting somehow and ended up with two stacks that don't have exactly the same color. The difference is subtle, probably a matter of which room lights were turned on and made minor additions to the light from the halogen illuminator. I corrected it as best I could for posting, and I suspect nobody but me would actually have noticed if I hadn't mentioned it -- oops!

--Rik

[JoanYoung]

Actually I did notice the difference in colour Rik, but thought it was on purpose for this excercise.
But you have given me the clue and I almost got it right, just a little more practice...the trick is to focus 18 inches away, then I almost get them to converge. If someone saw me now, they would think I am weird...well okay, I am weird, but not that weird...if you know what I mean.

[rjlittlefield]

Actually I did notice the difference in colour Rik, but thought it was on purpose for this excercise.

I couldn't stand it.

Through the miracles of Photoshop, the backgrounds are now identical. The colors of the seeds are still not identical. Closer I think, but not identical. But I have other things to do.

I'm glad to hear the stereo viewing is coming along. Keep me informed...

--Rik

[Ken Ramos]

You know this is funny. No not funny as in "ha-ha" but funny in as being unusual. When I visualize the large pair of seeds, they tend to stand out in 3D with really good relief but when I visualize the smaller pair at the bottom, they appear "concave," sort of like looking into a waspers nest.

[rjlittlefield]

You know this is funny. No not funny as in "ha-ha" but funny in as being unusual. When I visualize the large pair of seeds, they tend to stand out in 3D with really good relief but when I visualize the smaller pair at the bottom, they appear "concave," sort of like looking into a waspers nest.

Easily explained, Ken -- you're doing it wrong!

The pair at the top is designed for crossed eye viewing, left eye image on the right and vice versa. But the pair at the bottom is designed for parallel viewing, left eye image on the left. If the bottom pair looks concave, it's because you're looking at it cross-eyed! ("Parallax inversion" or "stereo inversion" are a couple of official phrases.)

That's why it is so difficult to switch back and forth between the two views and get proper stereo for each. For the pair at the top, your eyes have to be crossed, focusing beyond the convergence point. But for the pair at the bottom, your eyes have to be parallel, focused much closer than the convergence point. Making that switch is completely unnatural. I'm happy to say that apparently it is a learnable skill, since I found it was the devil's own time to do last night, but pretty simple this morning. (Yep, just checked. Less than two seconds per switch, and it doesn't even hurt!)

--Rik

[MacroLuv]

Seems it doesn't work for me.
Crossed eye... parallel view... or what ever... I always see as it is - a double photograph.

Here is "Left Brain - Right brain test".
Sometimes I see her spinning right, sometimes - left.
In "Find the man in the coffee beans" test I found the man in less than a minute but much quicker I found the repeating pattern in the coffee beans picture.

[rjlittlefield]

Interesting links, Nikola.

I can't quite figure out the pattern in the coffee beans. There are small spots of image that are exactly or almost exactly duplicated, but if you layer and shift in Photoshop you will see that duplication is restricted to only a few beans at a time. Apparently someone had fun with the clone tool! Oh BTW, it took me a long time to find the man. I misinterpreted the instructions and thought I was supposed to be looking for some clever large scale pattern, like the "face on mars".

The spinning dancer is great fun. I find it very hard to make her reverse. I think in part this is because when the spin reverses, the leg that is down has to swap sides -- when she is spinning CW, the left leg is down, but when she is spinning CCW, it is the right leg down! Perhaps it is good exercise for the brain to practice forcing the switch consciously.

For other excellent illusions and discussion, see Al Seckel's TED talk.

--Rik

[rjlittlefield]

Seems it doesn't work for me.
Crossed eye... parallel view... or what ever... I always see as it is - a double photograph.

Nikola, sometimes it helps to use some sort of barrier to block the confusing extra images. With crossed eye view, this is very easy:



For a barrier, you need nothing more than your hands.

Place both hands a few inches in front of your face, fingers pointed up, palms toward you. Close your right eye and slide your left hand toward center until your left eye sees only one image (the one on the right). Then close your left eye, open your right, and slide your right hand toward center until your right eye sees only one image (the one of the left). Now open both eyes, without moving either your hands or your head. Each eye should still see only one image. Now cross your eyes as needed to make the images fuse together.

You might also need to tip your head a little bit left or right, to get your two eyes exactly level with each other so that the images will be level with each other too. (My right eye is always a bit low unless I remember to level my head.)

With each eye seeing only one image, it should be easier to get the images to fuse into one image having depth. Then you have only the problem of getting your eyes to focus on it, even though the convergence is un-natural.

To make things easier, here is a crossed-eye pair that is smaller and will not need so much convergence.


I hope this is helpful. Let me know how it goes!

--Rik

[MacroLuv]

...
The spinning dancer is great fun. I find it very hard to make her reverse. I think in part this is because when the spin reverses, the leg that is down has to swap sides -- when she is spinning CW, the left leg is down, but when she is spinning CCW, it is the right leg down! Perhaps it is good exercise for the brain to practice forcing the switch consciously...
--Rik

Yep, seems it depends on how you interpret the image of the spinning dancer when she starts to dance. (i.e. if you think you stay in front of her or behind.)
Rik, thank you for that nice link.

... I can't quite figure out the pattern in the coffee beans. There are small spots of image that are exactly or almost exactly duplicated, but if you layer and shift in Photoshop you will see that duplication is restricted to only a few beans at a time. Apparently someone had fun with the clone tool! Oh BTW, it took me a long time to find the man. I misinterpreted the instructions and thought I was supposed to be looking for some clever large scale pattern...
--Rik

You are right Rik. There are duplicated coffee beans.
I was also looking at first for some contour or shape, not a photograph exactly. But after I noticed duplicated coffee beans finding the man was a piece of cake.
Seems I wasn't concentrated on task enough and that helped me to solve the problem!

Still seeing two photographs Rik.
Actually now I see two photographs and two hands!
Maybe it's time to visit my oculist.
Interestingly, while trying to cross my eyes I got another illusion - two photographs does not look parallel but forming an angle like "V".