From @rainmaker1973 on Twitter: "Your visual system constantly adapts to all the external stimuli, and this is why if you stare at this picture, it will slowly disappear"
Doesn't work for me!
When this curious contraption is switched on, an inner circle of white balls appears to be rolling inside the outer circle, but that's actually not the case at all. Below is a video explaining this circular motion illusion. Learn more about the mathematics behind it, specifically Copernicus’ Theorem, and the ingenious hypocycloid mechanical gear design by Girolamo Cardano (1501-1576) over at The Kid Should See This.
In this video, Caltech demonstrates the Rabbit Illusion, a "time-traveling illusion trick." It tricked me.
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Caltech researchers have developed these two new illusions that reveal how the senses can influence each other—in particular, how sound can give rise to visual illusions. These illusions occur so quickly that they illustrate a phenomenon called postdiction (as opposed to prediction) in which a stimulus that occurs later can retroactively affect our perceptions of an earlier event.
Steve Mould offers a couple of explanations for the flashed face distortion effect. I've seen this before and it's very strange. When you put pictures of two different people side-by-side and flash several pairs, the faces look like gross caricatures. By way of explaining it, he also presents a couple of other cool visual effects. Read the rest
Spatial frequency means how often things change in space. High spatial frequency changes means lots of small detail. Spatial frequency is surprisingly important to our visual system – lots of basic features of the visual world, like orientation or motion, are processed first according to which spatial frequency the information is available at...
Spatial frequency is also why, when you’re flying over the ocean, you can see waves which appear not to move. Although your vision is sensitive enough to see the wave, the motion sensitive part of your visual system isn’t as good at the fine spatial frequencies – which creates a natural illusion of static waves.
See Einstein below? Now go a few steps back from your screen and look again:
German sociologist Franz Carl Müller-Lyer (1857-1916) created an optical illusion that showed how changing the direction of angle brackets on line segments can make the segments look longer or shorter than they actually are. Artist Gianni A. Sarcone made a animated versions of the illusion and the effect is even more pronounced.
A Fata Morgana is a spectacular optical illusion in which you may see boats floating above the sea or city skylines in the clouds. (The term is named after the Arthurian sorceress Morgan le Fay as her castle was said to hover above the coast of Sicily.) In the video below, Seeker explains the science behind the magic.
(via Daily Grail)
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"No computer graphics tricks were used in this video," writes Jiri Zemanek of Czech Technical University in Prague.
Various patterns are generated in MATLAB using mathematical equations similar to ones describing Spirograph (or harmonograph) and Phyllotaxis. The patterns are calculated in such a way that when rotated under a stroboscopic light of suitable frequency or when recorded by a camera, they start to animate. It is kind of zoetrope---early device for animation. Eggs were painted using EggBot (designed by Bruce Shapiro as open hardware and available as a kit from http://www.evilmadscientist.com/). To draw on eggs, we used standard permanent markers and an electro kistka with bee wax followed by dying. Eggs are rotated at a constant speed, special for each pattern, by a brushless motor.
Here's more: "This apparatus creates stroboscopic patterns on an egg covered in photochromic paint"