How we see 3D??

A stereo image is basically a 3D image. We have seen a lot of “virtual reality headsets” in 2015( Learn more about VR here, I have a bunch of articles on VR Google VR, VR vs Hologram, Best apps for Cardboard VR, How to make a cardboard VR DIY). If we look at the phones screen without the VR set, the image we see is a stereo image. The image below is a stereo image.


When we look at an object, both of our eyes looks at the same object. Two set of images are formed, one with each eye. Then our brain manipulates and merges both images to give us a 3D view.

So, now we get an idea on how we see in 3d. Then how do we see 3D video on a 2D screen??

Well.. The basic requirement to see in 3d is to have two images one for each eye. To do this on a 2d screen, we may project a stereoscopic view( the image above is a stereo image) and separate each eyes view.

This sounds great, but doesn’t work in a movie theatre with many people.

To overcome this problem, we started overlapping the image. Ok, now how those two overlapped images are separated for each eye?

Here comes the Polarised glasses. Both the overlapped images on the screen are polarized in a different way, each lens on the glasses are used to match the respective polarization. There we go, we have one image for each eye. But if we look at the image without glasses, the image looks something like this;)


This is how we experience 3D:)



Why do mirrors flip horizontally but not vertically?

Mirrors are great, we often look at our self in the mirror. But the mirrors show a horizontally flipped image of our self, why? The answer for this question is very simple, it’s not the mirrors fault, we are the one who flip the object from the reading position. If we try to read the text on our shirt in the same position in which we wore, it results in a mirror image. To read the text we should have to flip the shirt to the reading position that is the opposite direction.

But here is the thing, if we point out the arrows up, down, right, left precisely in the X and Y directions, the images will be shown correctly. Now go ahead and put an arrow towards the mirror, the mirror image points out in the opposite direction that is it points you… Watch out the image below for more clarity. So, now this shows that the mirror is actually changing the image. Your right hand becomes left hand in a mirror and vice-versa. Well… Lets see this way, put on a pair of glouse, now reverse the right hand glouse. It should fit your left hand. So the mirror is actually changing the Z direction.


 Now, why the vertical flip is not happening?

From the above explanation it is clear that, it is we who are responsible for the horizontal flip. But yes the mirror do manipulate in the Z direction. We won’t experience vertical flip because we are not vertically symmetric to the mirror.

Hope you got the answer…