You guys like optical illusions?
Here's one you might be familiar with.
It's called...
The Thatcher Effect
Upside down this looks like a perfectly normal photo...
...of the Spectics Guide to the Universe podcast co-host...
...Jay Novella.
But if we turn it right side up...
...eeeeeurrhg.
Right?!
Other optical illusions can be quite elegant.
For instance, the...
...Ambiguous Cylinder, Rectangle and Circles illusion...
By Kokichi Sugihara
I couldn't get clearance for the accompanying music...
...by Yoko Sugihara...
...so I'm going to approximate it with my own original composition.
*hits keyboard ever so gently*
The video shows various round cylinders...
...reflecting in the mirror as square cylinders and vice versa...
...in different combinations.
Seems like it could not have been done without some sort of visual effect.
But amazingly...
...it was!
This IS just a mirror...
...and everything was captured by the camera...
...as it appears.
How was it done?!
Well...
A busy little 3D-printing beaver...
...was quick to demonstrate...
...the basic technique.
So very, VERY quick.
But some questions still remain unanswered...
Like... how was this piece done?
And why are 3D-printers still so terrible at the thing they're designed for?
So let's figure out exactly how the illusion works...
...and explain each object featured in the video...
...using nothing more, than...
...STATE OF THE ART COMPUTER GRAPHICS.
Here's a flat square. ■
We can depict it rotating 3 dimensionally in a 2D video with PERSPECTIVE CUES.
But these cues are ambiguous.
You might be looking at a square straight on...
...OR a trapezoid at an angle.
In 2D there's no way to know for sure.
By using an object's shape to counteract perspective...
...we can secretly encode a completely different shape...
...in the same object.
The ambiguous cylinder is ambiguous because it's neither round, nor square.
It's halfway inbetween.
And it can be nudged to one extreme or the other...
...by the perspective of the angle from which it's viewed.
We have to decide on this angle before we can modify the cylinder's top and bottom...
...to make the illusion work.
Let's use 45 degrees looking down.
Just like in the video.
The mirror reflection is the same 45 degree angle from the opposite side.
To make the cylinder look more round from this view...
...we need to flatten the top and bottom corners...
...while streching the side corners vertically.
Coincidentally...
...to make it look more square from here...
...we need to pinch the side corners...
...while streching out the top and bottom.
Both adjustments can be made simultaneously...
...by distorting the edge vertically into an S shaped curve...
...tuned precisely for our viewing angle...
...but without rotating the edge surface.
We also have to tweak the sharpness of the vertical corners...
...for the focal length of our camera's lens.
The kind of technical detail...
...that some "make-anything" PUNK...
...WOULDN'T KNOW ABOUT!
Okay... (offscreen) CAPTAIN!
WHAT?!
I... these kids...
They put things up over night and then get 3 million views!
And I'm sitting on my...
The resulting effect is flawless.
As long as we light the object softly to get rid of telltale shadows...
...and keep the viewing angle exactly the same.
Changing the camera's position...
...or even the lens' field of view...
...would cause the effect to break down.
All the different shapes featured in the video...
...are variations of the same initial object.
The six adjacent cylinders...
...are six adjacent cylinders.
The four intersecting cylinders...
...intersect at slightly varying heights...
...making it possible to hide the intersection on the square side.
The 12 nested cylinders...
...have the inner ones reversed...
...and connected to flat bridges at appropiate angles.
And the 2 disconnected cylinders...
...are actually attached at an offset height...
...and use a false corner piece...
...to make it seem like they're intersecting on the square side.
Together they make up a masterful illusion...
...worthy of the 2016 "Best Illusion of the Year Prize".
Or is it "Illusion of the Year"?
Correlate your neurons Neaural Correlate Society!
Ahhh...
Isn't it nice to understand something SO THROUGHLY...
...that you're sick of it, and never want to see it again?
Now about the spinning dancer illusion...
Before we debate which direction she's really spinning in...
...let's agree on ONE thing...
...THAT'S NOT A DANCE MOVE.
Okay?!
She's falling over while bouncing on her heel.
What kind of dance is that?!
*whoosh*
*outro music plays*
Subtitles made by: Flummox3d