
Topology-disturbing objects: a new class of 3D optical illusion (2017) - aesthesia
https://www.tandfonline.com/doi/full/10.1080/17513472.2017.1368133
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FatalLogic
Video is the best way of showing how strange these can appear -

[https://i.imgur.com/g5Ot0rH.gif](https://i.imgur.com/g5Ot0rH.gif)

Source -
[https://www.thingiverse.com/Matsemann/collections/matsemanns...](https://www.thingiverse.com/Matsemann/collections/matsemanns-
ambiguous-cylinders)

~~~
yorwba
Your source link helped me find where it had been posted on HN by the creator
of those models before:
[https://news.ycombinator.com/item?id=18307573](https://news.ycombinator.com/item?id=18307573)

The top reply to that comment pointed out that you can rotate the models in
GitHub's viewer:

[https://github.com/Matsemann/impossible-
objects/blob/master/...](https://github.com/Matsemann/impossible-
objects/blob/master/3dfiles/arrow/filledarrow_whole.stl)

[https://github.com/Matsemann/impossible-
objects/blob/master/...](https://github.com/Matsemann/impossible-
objects/blob/master/3dfiles/circlesquare/circleinnersquare_2x2.stl)

~~~
bonoboTP
I never knew it's so simple to embed 3D visualizations. How does GitHub do
this? How can I do this on my own website? What's the name of the tech I
should google?

~~~
TFortunato
My guess is you want to start by looking at three.js --I've been on teams
using it for a robotics debugging tool with a web interface, and it's
definitely a nice library to work with!

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yarg
This is old enough that the year (2017) should be in the title.

Also, the optical illusion isn't really 3d since it relies on a single point
perspective - it'll show up on camera, but if you see it with two eyes you'll
see the actual structure.

Now for a real 3d optical illusion, look at the hollow face illusion - not on
video - find a real life instance of a depth reversed face.

Your brain has circuitry specifically optimised for facial recognition, and
what you're seeing so confuses your mind that it breaks depth perception.

It will actually appear as if a static object is turning to follow you around
the room.

~~~
ColinWright
> _.. if you see it with two eyes you 'll see the actual structure._

I'm interested to know if your statement based on personal experience.

I have some of Sugihara's work, and what you claim is not the case. If you
view it from a sensible distance (over 30 cms or so), and even if you know how
it works, the illusion is still effective.

Of course the illusion disappears if you view it from radically the wrong
direction, or from less than 10 cm, but based on my experience, your claim
seems over-stated.

~~~
yarg
Even then, it's still not 3d - it's based on lighting and a lack of contrast -
it's a projection based illusion that requires distance so that the variations
between the two two-dimensional projections are not enough that your brain re-
comprehends what it's looking at.

I'm not saying it isn't cool - there's something quite neat about the fact
that the brain misinterprets what it's seeing as the nearest known 2d icon.

But it's not 3-dimensional.

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jacknews
Cool.

STLs? Would love to print a couple of these for my kid's show-and-tell in
class

edit: found some , search "illusion" on thingiverse, not "topology" :)

eg,
[https://www.thingiverse.com/thing:3169391](https://www.thingiverse.com/thing:3169391)

~~~
maaaats
My whole collection is here:
[https://www.thingiverse.com/Matsemann/collections/matsemanns...](https://www.thingiverse.com/Matsemann/collections/matsemanns-
ambiguous-cylinders)

Do it, I have shown these to various school classes. They have been popular
everywhere, from primary school to universities!

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caleb-allen
Is this the same type of illusion?

[https://www.youtube.com/watch?v=oWfFco7K9v8](https://www.youtube.com/watch?v=oWfFco7K9v8)

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Pelam
"Keywords: ... anomalous object, impossible object, ..."

Will somebody please call SCP already ;)

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zaarn
Uncounted number of dead D-class personal and MTF squads later, it's concluded
that it's safe.

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ur-whale
OBJ file anyone ?

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lisper
[https://www.thingiverse.com/Matsemann/collections/matsemanns...](https://www.thingiverse.com/Matsemann/collections/matsemanns-
ambiguous-cylinders)

That link has STL, not OBJ, but maybe that's good enough.

~~~
ur-whale
Very neat, thanks.

Loading one of these things in blender and rotating it around is really worth
doing, and it's totally weird: when you rotate most 3D objects interactively,
you can get a good grasp of their shape, but these things feels like they are
specifically designed to prevent that from happening.

~~~
matsemann
Yeah, the weeks I spent making that collection was quite mind-bending, hehe.

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louis8799
forget the math, just enjoy

