Dancing Arrows To Break Your Brain

Last year, mathematician and professional optical illusionist [Kokichi Sugihara] came up with an arrow that only points one way. Technically, it’s ‘anomalous mirror symmetry’, but if you print this arrow and look at it juuuussst right, it appears this arrow only points one way.

[Ali] had the idea to turn this arrow illusion into something motorized, and for that he turned to 3D printing. The models for the illusion arrows were already available, but there had to be a way to turn a single arrow into an art installation. For that, you just need a few 9g servos. [Ali] slightly modified his servos so they would turn a full 180 degrees, and designed a magnetic mount to allow easy swap-out of these arrows.

The servos are attached to a 3D printed frame with heat-staked threaded inserts, and driven by a Pololu servo driver. The effect is great, with multiple arrows twisting and turning but still only appearing to point to the right. [Ali] put together two videos of this arrow illusion, one that’s effectively a build guide, and of course all the STLs are available in a link in the description.

Continue reading “Dancing Arrows To Break Your Brain”

Hack Your Brain: the McCollough Effect

There is a fascinating brain reaction known as the McCollough Effect which is like side-loading malicious code through your eyeballs. Although this looks and smells like an optical illusion, the science would argue otherwise. What Celeste McCollough observed in 1965 can be described as a contingent aftereffect although we refer to this as “The McCollough Effect” due to McCollough being the first to recognize this phenomena. It’s something that can’t be unseen… sometimes affecting your vision for months!

I am not suggesting that you experience the McCollough Effect yourself. We’ll look at the phenomena of the McCollough Effect, and it can be understood without subjecting yourself to it. If you must experience the McCollough Effect you do so at your own risk (here it is presented as a video). But read on to understand what is happening before you take the plunge.

Continue reading “Hack Your Brain: the McCollough Effect”

Before Film There Were Zoetropes. Now We Have 3D Printed Zoetropes!

Reddit user [eyelandarts] has produced a rather unique 3D printing project. A 3D printed Zoetrope.

You see, a zoetrope was a device that created an animation effect that pre-dates film technology. It would create the illusion of motion much like a flip book does, but with a spinning cylindrical wall with slots cut into it. As the cylinder spins, you catch a glimpse of the animation through the slots. But, it’s just a 2-dimensional animation — what if you replaced it with an ever changing 3D model?

It’s actually been done before. A long time ago in fact. In 1887, [Etienne-Jules Marey] created a large zoetrope to animate plaster models of a bird in flight. Fast forward to today, and [eyelandarts] has 3D printed something similar — but ditched the cylindrical wall. Instead, a strobe light is used to see the animation!

The end result is quite awesome if we do say so our-selves. For another fun take on Zoetropes — how about a digital one made out of tiny LCD screens?

Siezure-warning… there’s a very flash-tastic demo gif embedded after the break if you’re brave enough to view such a thing.

Continue reading “Before Film There Were Zoetropes. Now We Have 3D Printed Zoetropes!”

Spliced Animations come to life on their pages

Remember those flipbooks you doodled into your history textbooks while you waited for the lunch bell? [Maric] takes the general principles of flipbooks and turns them on their head, giving our brain a whirl in the process. By splicing multiple frames into one image, he can bring animations to life onto a single page.

The technique is simple, but yields impressive results. By overlaying a pattern of vertical black bars onto his image, only a small fraction of the image is visible at any given point. The gaps in the pattern belong to a single frame from the animation. As [Maric] slides the pattern over the image, subsequent frames are revealed to our eyes, and our brain fills in the rest.

A closer look reveals more detail about the constraints imposed on these animations. In this case, the number of frames per animation loop is given by the widths in the transparency pattern. Specifically, it is the number of transparent slits that could fit, side-by-side, within an adjacent black rectangle.

The trick that makes this demonstration work so nicely is that the animated clips finish where they start, resulting in a clean, continuous illusion.

Don’t believe what you see? [Maric] has linked the pattern and images on his video so you can try them for yourself. Give them a go, and let us know what you think in the comments.

Continue reading “Spliced Animations come to life on their pages”