Tag: optical illusion

Looking into Einstein's head (optical illusion)

By Phil Plait | August 3, 2012 7:00 am

Wow, it’s been forever since I’ve posted a brain-melty optical illusion, and I love me some illusions. This one is a variation on one I’ve posted before, showing how an ambiguously lit object freaks your brain out trying to figure out the lighting.

I really wish we had a show as smart and wonderful as QI here in the US. I love Stephen Fry as much as I do illusions!

Anyway, there are lots of examples of this type of illusion. Here’s one of a silhouetted figure spinning that’ll destroy you. This is also similar to the dome/crater illusion as well, where something (a crater) lit from below makes it look like an inverted object (a dome) lit from above.

I have more illusions listed in Related Posts below. Seriously, click the Blue/Green link. Oh my, that one is AWESOME. And people still argue over it in the comments, despite my complete and rock solid proof of what you’re seeing in it. Optical illusions really can mess you up.


Related Posts:

The blue and the green
You spin me right round
This video illusion will destroy your brain
Raising an impact in Africa
Sunsets are Quite Interesting
Sunsets are Fryed astronomy

CATEGORIZED UNDER: Cool stuff, Humor, illusion

Best illusions of the year

By Phil Plait | June 5, 2011 7:00 am

I love optical illusions (see Related Posts at the bottom of this article for more), so I was happy to discover that every year, the Neural Correlate Society has a contest to find the best ones. This year’s Top 10 finalists have been announced.

My favorite (which I can’t embed here, sorry) is called "Grouping by contrast". You’d swear the spots are not the same color, but I cut two holes out of a piece of paper to block the background, and sure enough they are. It’s incredible. The illusion is a variation on the well-known chessboard contrast illusion and is similar to another illusion showing that how we see colors isn’t as straight-forward as you might think.

Another cool one is this:

Click play, and stare at the white dot in the center. You can easily see the dots changing color… until the dots appear to rotate. They suddenly seem to stop changing color, but in reality they still are. Rerun the video and look at the dots instead of the center, and you’ll see.

The best illusions are the ones where you’d swear it’s a trick. But that’s the whole point, isn’t it? So go to the list and check out the other finalists. And remember: seeing is not believing. You cannot always trust your eyes and brain to give you a good picture of reality.

As a skeptic, I find that knowledge comes in handy quite often.

Tip o’ the Escher staircase to slashdot.


Related posts:

The blue and the green (one of my most popular blog posts of all time)
This illusion will drive you mad
Video illusions
Why does the Moon look so huge on the horizon?

CATEGORIZED UNDER: Cool stuff, illusion
MORE ABOUT: optical illusion

Saturn brain bender

By Phil Plait | October 6, 2010 7:00 am

Usually, pictures of Saturn aren’t too hard to figure out. Planet, rings, moons, and so on. But then this picture showed up, and I had a real What the frak?* moment:

cassini_saturn_brainbender

I have to admit, it took me a few seconds of disorientation before suddenly the picture geometry snapped into my brain. It was like one of those optical illusions where once you see it, you can’t not see it!

So what’s going on here? Actually, a lot! So strap yourself in.

Read More

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Video Illusions

By Phil Plait | July 10, 2010 7:30 am

I love optical illusions, and I’m fascinated by the mechanics of vision, so I have to share with you this video. This technique of animation has been known for a long time, but it’s still pretty cool.

Another video discusses how this is done. I had a card I carried in my wallet for years that did a similar type of illusion using a lenticular overlay which, when you moved the card back and forth, made it look like little colored spirals were rotating in different directions. I bought it when I was in college, but sadly I lost it last year (I’m pretty sure I dropped it at Comic Con). I have no idea how to replace it. If any of you has seen something like it, please let me know!

Tip o’ the Fresnel lens to BABLoggee Cristiana Senni.

CATEGORIZED UNDER: Cool stuff
MORE ABOUT: optical illusion

A lunar illusion you'll flip over

By Phil Plait | May 19, 2010 9:26 am

The Lunar Reconnaissance Orbiter has a great blog where they post images from the hi-res camera onboard. I was perusing a recent image, and was a bit befuddled:

LRO_dome_crater

What the heck? Is this a plateau of some kind? Is that a small dome just below the center of it? The whole thing looks pitted around the edge, too, like some sort of erosion has taken place. But that can’t be right!

Happily, being an old hand with optical illusions, I knew exactly what to do. I flipped the image over, and all became clear:
Read More

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Why does the Moon look so huge on the horizon?

By Phil Plait | May 13, 2010 7:00 am

moonillusionI love illusions, and I love astronomy. So what could be better than combining the two?

If you’ve ever seen the Moon rising over the horizon, looking so fat and looming that you felt like you could fall right into it, then you’ve been a victim of the famous Moon Illusion. And it is an illusion, a pervasive and persuasive one.

So, how does this thing work? Ah, step right up.

One of my favorite brain-benders is the Ponzo Illusion. You’ve seen it: the simplest case is with two short horizontal lines, one above the other, between two slanting but near-vertical lines. The upper line looks longer than the lower line, even though they’re the same length.

ponzo_schematicThe illusion works because our brains are a bit wonky. The slanted lines make us think that anything near the top is farther away; the lines force our brain to think those lines are parallel but receding in the distance (like railroad tracks). The two horizontal lines are physically the same length, but our brain thinks the upper one is farther away. If it’s farther away, then duh, our brain says to itself, it must be bigger than the lower one. So we perceive it that way.

While procrastinating on reddit, (you do look at reddit, don’t you, especially the science section?) I found this beautiful example of Ponzo:

ponzo_illusion

Heehee! You’d swear up and down* that the red vertical line on the right is much longer than the one on the left, wouldn’t you? It looks almost twice as long to me. It’s a very powerful perception.
Read More

A wicked illusion

By Phil Plait | May 3, 2010 12:00 pm

This is a very cool short video showing a nifty little illusion. I had it figured out about 1/3 of the way through because, after all, I am a supergenius (or, more likely, I spent my youth and a goodly part of my adult life playing with illusions). Take a look:

2D/3D illusions like this are really fun, but also something to keep in mind with a lot in visual sciences; our brains are so easy to fool with such things, making us think objects are closer or farther, smaller or bigger, than they really are. If only most UFO enthusiasts could appreciate this…

CATEGORIZED UNDER: Cool stuff
MORE ABOUT: optical illusion, UFOs

Terra spots an impact on, um, Terra

By Phil Plait | February 1, 2010 7:00 am

While high over the grasslands of Kazakhstan, the Terra Earth-observing satellite saw something interesting… can you spot it in this image?

terra_chiyli_lrg

Not so easy, is it? But if you look just left of center you’ll see this:

terra_chiyli

See it there, right in the center? It’s the Chiyli impact crater, an ancient scar from a cosmic collision. The crater is roughly 1.5 km across (about a mile) — about the same size as Meteor Crater in Arizona — meaning the object that created it was something smaller than a football field, moving at perhaps 30 km/sec (20 miles/sec). It hit about 46 million years ago, give or take. Long after the dinosaurs, but long before us, too. Note that it’s a double-rimmed crater too, which sometimes form in large impacts depending on the conditions of the impactor and the ground.

This is a false-color image, at least part of which is in the infrared; vegetation appears red, water blue, and bare land is "earth tones" (browns and tans). This sort of imagery allows scientists to investigate how vegetation, land, and water change over time.

terra_chiyli_flippedWhen I first saw this image, I didn’t see it as a crater, but more as a raised annulus, a ring in the ground. I knew immediately that this meant that in the picture, the sunlight was coming up from the bottom, and it turns out that’s correct. It’s a cool and optical illusion; when we see craters illuminated from below, they look like domes, and vice-versa. In the picture here, I flipped the image and now, to me at least, it looks more like the depression that it really is. The wide inner rim is more obvious, too.

Here’s an even better example:

Is it a dome… … or a crater?

It just goes to show you that finding evidence of extra-terrestrial events on Earth can be tough, and even when you find them you can’t rest easy. They’re apt to fool you one way or another.

CATEGORIZED UNDER: Astronomy, DeathfromtheSkies!
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