This optical illusion requires a little more work than most - you're going to need to do some serious eye-crossing, for a start - but it's worth it. There's a half-dozen different tricks packed into this one spinning rhombus.
This video is the work of optical illusions creator Rex Young in collaboration with artist Terry Pope - you can check out Young's YouTube channel to see more of his work. A little background is need for this video. Originally, the basic illusion was designed to be seen using a pseudoscope, which uses mirrors to reverse visual information so that the left eye sees what the right eye normally would, and vice versa.
To achieve that same basic effect, Young recorded the rhombus spinning using a stereoscopic camera, and then flipped the left and right frames in the finished video up top. All you need to do is cross your eyes until the two spinning rhombuses overlap, creating what appears to be a single 3D shape, and you're ready to go. In case that's proving difficult - and I'll admit I had a bit of trouble with it myself - you can go here for some tips on how to see it in glorious fake 3D.
Yes, this is more convoluted that your average optical illusion - although I'm not really sure elegance is something I particularly look for in these things anyway - but you get a lot of bang for your buck here. These are the six effects one should be able to see, even if it takes a little work:
1. The spinning rhombus appears to switch directions
2. Striped band appears to rotate in the opposite direction of the rhombus
3. Red cube floats in space
4. Red cube becomes transparent
5. Red cube rotates impossibly
6. The light falling on the rhombus appears to come from a source opposite its real source
So what's behind all these different effects? The good folks at New Scientist explain:
When we view a scene, the image that appears on our retina is two-dimensional, so our visual system uses a variety of cues to add depth. One of these involves comparing the position of images on the left and right retinas to determine distance. Since the images in this video have been flipped, it reverses our distance cues, causing far away points to seem closer than nearer ones and altering our perception in a variety of ways.
Like I said, this optical illusion can take some work, especially if you want to see all six of the different effects. If you're looking for something that falls squarely in the category of "ludicrous but still kinda awesome waste of time"...well, I can't imagine you'll find much better than this.
Via New Scientist.