Sugihara's Dog(twitter.com)

258 pointsby sohkamyungvor 3 Jahren25 comments

https://twitter.com/AkiyoshiKitaoka/status/1642871991932944385

29 comments

js2vor 3 Jahren

If you, like me, are one of today's lucky ten thousand[1], here's some context:

Kokichi Suhihara is an engineering professor who designs 3D objects that create optical illusions, including their mirrored images. Here's his English home page:

http://www.isc.meiji.ac.jp/~kokichis/Welcomee.html

So we're looking at a photo of an actual 3D object and its mirrored reflection, which should obviously appear incorrect since, well, the reflection is not apparently mirrored but rather facing the same way as the real object. I think the key to understanding what we're seeing is that the non-mirrored image is also not as it appears. We'd need to see it rotated to understand the actual shape.

Here's a short YouTube video of his "Ambiguous Garage Roof" that I've now watched several times and it keeps blowing my mind:

https://youtu.be/KtA6u1HIqbg

[1] https://xkcd.com/1053/

omershapiravor 3 Jahren

Funny story: In 1984, my mom, a Computational Geometry researcher, saw a proof [1] in some IEEE journal that she was annoyed with. It seemed way too general and was too easy to disprove, so she did [2], in a subsequent publication, with the author's name in the title.

She later told me he courteously publicized a correction, credited her, and would mail her pre-prints for his papers since. Earlier this year I looked up the claim and counterclaim: Turns out it's Kokichi Sugihara.

I guess in the 80s well-actuallying in Mathematics journals was good form. :)

[1] https://ieeexplore.ieee.org/document/4767571

[2] https://ieeexplore.ieee.org/document/4767487

the_afvor 3 Jahren

> Here's a short YouTube video of his "Ambiguous Garage Roof" that I've now watched several times and it keeps blowing my mind:

> https://youtu.be/KtA6u1HIqbg

What the...

What's amazing about the Ambiguous Garage is that even after I've seen how the illusion is done, my brain keeps getting fooled. It's one of those things where it's simply impossible not to "see" the illusion even after you understand it.

js2vor 3 Jahren

It reminds me of the Penn and Teller red ball routine where they tell you how it works before they perform it and your brain (well, mine anyway) still won't accept it.

https://youtu.be/W2T-YUd_Om4

https://www.thisamericanlife.org/extras/the-floating-ball-ro...

avpixvor 3 Jahren

This is a fantastic demonstration of a pseudovector! https://en.wikipedia.org/wiki/Pseudovector

[deleted]vor 3 Jahren

dark-starvor 3 Jahren

His illusions are awesome. Even if you know how they work (watch his videos), your brain will still not be able to completely comprehend them.

That's what makes a good optical illusion.

coldpievor 3 Jahren

It took me an embarrassingly long time to even realize what the illusion was.

chillbillvor 3 Jahren

I didn’t even see that there was a mirror

DMellvor 3 Jahren

I still don't. Can someone explain?

lm28469vor 3 Jahren

The dog appears to be facing the same way, even in the reflection

Hamukovor 3 Jahren

How do objects normally appear when viewed in a mirror?

DMellvor 3 Jahren

Okay - wow..

IIAOPSWvor 3 Jahren

reflected

0xbadcafebeevor 3 Jahren

[deleted]vor 3 Jahren

too_damn_fastvor 3 Jahren

Is it supposed to be the shiba inu image that replaced the Twitter Bird?

[deleted]vor 3 Jahren

BelleOfTheBallvor 3 Jahren

Searching on YouTube doesn't seem to bring anything about the one linked here, am I putting in the wrong term? I'd love to know how this was done, it's messing with my head.

bejdvor 3 Jahren

From finding his name in the Twitter comments, his channel seems to be https://www.youtube.com/@kokichisugihara3277

paulette449vor 3 Jahren

Ambiguous Cylinders 1 & 2 by Sugihara:

https://www.youtube.com/watch?v=SzC-pV_moFc

https://www.youtube.com/watch?v=NxspLn-B8DE

SynasterBeitervor 3 Jahren

This guy took inspiration from him and is 3D printing more variations on these illusions.

https://www.youtube.com/watch?v=22x4aALI0VE

BelleOfTheBallvor 3 Jahren

Oh, this is really interesting, he goes into detail on how difficult it can be to print them, too, based on the fact that you have to make the parts moveable and a lot of them are somewhat small, too. Thank you!

IIAOPSWvor 3 Jahren

Remember folks, if you're unsure, illusions don't have shadows.

turtleyachtvor 3 Jahren

That.. sounds like you have a bag of old-school RPG tricks? I wish you did. Thanks for this one.

IIAOPSWvor 3 Jahren

Thanks. I meant it literally and figuratively. Literally, drawing shadows of optical illusions generally makes them stop being optical illusions. Figuratively, all illusory experiences (magic tricks, scams, psychotic delusions) tend to have some mundane inconsistency which is likely to go unnoticed, but if you know to look for it the illusion evaporates. Illusions don't have shadows.

hammockvor 3 Jahren

Is there a place to buy these? Or download the plans and somewhere that will print them for you?

CobrastanJorjivor 3 Jahren

Here's a star/heart that's the same idea: https://www.myminifactory.com/object/3d-print-ambiguous-star...

I've printed it and physically fiddling with it made it much more clear how it worked.

I haven't seen a print for that dog, though.

In theory, I think you could use Sugihara's approach to automatically generate such a model for most closed curves. That'd be a cool little program that I don't know how to write.

pvaldesvor 3 Jahren

So the dog structure is a "3D palindrome", it seems.