So-called holographic projection

Going to a minibus in a county, a friend handed me his mobile phone and whispered mysteriously, "Look!" "

I glanced at the screen. On the screen, a woman was singing softly, and the audience was gazing deeply.

I saw a few big characters on the video title:

Although he pretended to be disdainful, Kim was really surprised to see the title.

"This designer has scolded Yau Tsim Mong for so many years and has never seen such a magical holographic projection technology!" , silently OS in my heart.

Take a deep breath and keep looking.

From hair to clothes, I tried to figure out every pixel, hoping to find a clue.

When the eyes fall on a woman's feet,

My tight mouth finally smiled. "I found it!"

"A scam," I whispered to my friend.

Looking at his friend's puzzled eyes, Kim felt obligated to study holographic projection.

Why can you tell from your feet that it is a scam?

To answer this question, we have to start from the beginning.

First of all, there are three so-called holographic displays so far:

So the name is incredible, that is, using water vapor or dry ice as the medium, projecting the picture onto the medium.

Because fog can reflect light and penetrate the line of sight to a certain extent. Therefore, in a specific environment (the environment is dark enough, the fog is relatively flat and the density is uniform), the visual effect of the three-dimensional picture suspended in the air can be achieved. For example, water curtain movies in many scenic spots now.

However, its disadvantage is obvious: fuzziness. The movement of fog can't be controlled, which makes the surface for reflection uneven. We know that the smoother and clearer the surface reflection, the rougher the surface reflection (imagine the reflection of marble floor compared with that of cement floor). Therefore, the image projected by the fog surface will be hazy. Moreover, due to the uneven thickness of fog, some parts of the picture are sometimes missing.

But then again, this real and illusory effect is not necessarily an advantage for some special effects.

Use a high-speed rotating mirror to produce a visual effect of a suspended picture.

The principle is to use a rotating glass to reflect the projector picture and rotate it to different angles to play the picture that the audience at that angle should see.

However, smart you have to ask again, how can you serve every angle of 360 degrees with only one piece of glass?

Suppose our motor rotates once every 0.36 seconds, how long does it take to rotate once? (0.36/360 ? = 0.00 1 sec)

Ok, all we have to do is play a picture every 0.00 1 second.

0 degree, playing the picture observed by the audience from 0 degree; After 0.00 1 sec, the mirror rotates 1 degree, playing the picture observed by the audience from 1 degree ... and so on to 360 degrees. It turns so fast that you can't feel it.

Is it cheating? No matter where you stand, you can show what you should see when you stand there.

Ionize the air with a laser, so that the specific position you want in the air shines, resulting in a suspended three-dimensional painting.

This is the holographic projection that most people imagined before reading this article. Iron Man, the cool holographic images in Star Wars, including the recent mobile crusher team, are all based on the imagination of this technology.

However, due to the complexity and immaturity of technology, the holographic image of this principle only exists in the laboratory at present, and it has a small range and few colors (it seems to be monochrome at present).

This is the kind of "holographic" stage we have heard of. The picture comes from the bottom (or the top), and the picture on the ground is "upright" by using a transparent reflective film with an angle of 45 degrees with the ground, resulting in the effect that the picture is suspended in the air.

Smart you have to ask again, why is it 45 degrees? Wouldn't it be better to make the reflective film vertical? In other words, it saves space and is simple?

Well, your questions are very good. You have many questions.

Let's review the basic knowledge of physics first.

What people see is essentially that light enters the human eye, right?

Then we hope everyone in front of the stage can see this painting. Should we shoot light horizontally?

Ok, now you know why it's 45 degrees, right? This angle just allows the picture lying on the ground to be reflected at a horizontal angle.

The above four "holographic" display technologies have an important similarity: they are all real live media displays (visible on the spot). Not synthetic.

Let's look at the singer's feet again:

Did you get a look at him? Obviously floating up and down, as if suspended in the air. If it is not intentional, this situation will not appear in the media display on the spot. Simply put, this picture is superimposed and can't be seen at the scene!

Also, please note that it has no reflection! Please imagine that in reality, whether it is a water curtain movie or a mirage, there are reflections. On such a bare stage, if this picture is true, then you can see the performers clearly, and you must see the reflection.

All "holographic" technologies on the market are reflective projection imaging, and the basic principle is actually the same as showing movies in cinemas. As we all know, in cinemas, movies must be shown in a dark environment, and so is the "holographic" screening. Let's take a look at the "hologram" of Japanese TV station. The environment is very bright, brighter than any projector. Making a "holographic" projection in this environment is like watching an open-air movie in the midday sun-you can't see anything.

On the other hand, although I call it a scam, the real liar in the video is just an affectionate audience. As for technology, although it is not "holographic", it is also a real high-tech. I dare say that if the production team handled it more carefully, it would be possible to be completely flawless.

In this video, it is the technology that is now blown to the sky: AR(MR, virtual implantation, mixed reality, or anything else ...... all the same). But this AR is not the same AR, which is much more advanced than the mobile phone AR you play.

At the same time, this article was posted to "design_hack" on the official WeChat account.