Wednesday, November 28, 2012

Anamorphic Illusions

This video is a little bit mind bending.  Things are not as they seem.  Several of the items are not real, they are just pictures printed on paper.  The fun part about it is that they are projections designed to look correct and 3 dimensions from a particular point of view.  When the camera looks at the image from that point of view all appears fine, but when you move the image, everything sort of breaks down.  Watch the video then continue reading below.

What is going on here?
This video plays on the fact that with a camera, they can carefully control your point of view.  Because you are looking at a single image, your two eyes see exactly the same image and thus you aren't getting any depth information from parallax.  In fact, it seems to me that usually it isn't your two eyes that give you depth information as much as it is the view from different positions of your head that allows your brain to construct a 3D image.  In this case, based on your experience in the world and your familiarity with objects that look like these, your brain makes some assumptions.  In this case, those assumptions are wrong.

When sunlight (or other light) hits an object, some wavelengths of the light are absorbed.  What isn't absorbed bounces off.  The wavelengths that bounce off and find their way to our retina are the color we perceive objects to be (more about that later).  The light bounces off the object in all directions, but some of it will be bouncing toward your retina and if nothing is in the way, it is these that you will perceive.  Since these photons travel in basically a straight line (modulo some effects of gravity etc) what your eye senses is a particular color of light at a particular position on your eye.  This position maps to an angle that the light comes from.  Your brain, through years of experience know to interpret this as source of light of that color along a line (or more specifically a ray) at a given angle from your eye.  What you don't perceive, is haw far away it is.  You really only get a color and direction.  That is why you brain can be fooled about size and 3D shape.  I made a funny-looking diagram below to try to explain this:

When you see an object, you get the angular and color information that I mentioned above.  When you look at a video of an object, you are seeing the camera's Point of View (POV) projected onto a screen so that when you look at the video, your brains is fooled into thinking you are looking through the video to the object beyond.  Well, that projection concept can work in the other direction as well.  If you continue those rays away from your eye onto a piece of paper, you end up with a view of the object that looks very distorted if you look at it from a perpendicular perspective, but if you look at it from exactly the right point of view, it will look just as if the object if standing in front of you.

The original photos from the video are included below.  If you hold them at just the right angle, you may be able to see the effect for yourself.  In fact, you can print them out and make your own video just like this one.

If your mind isn't warped enough yet, I promised you a little mind bender about color... take a look at the video below.

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