Shulou(Shulou.com)11/24 Report--

Did friends ever fantasize about the ability to be invisible when they were young?

Or have the invisibility cloak from the Harry Potter movies to make yourself invisible.

In real life, someone has realized the ability of invisibility through technical power, and he has more than one way to share it!

There is something like this:

It goes like this:

And something like this:

And the final plan he figured out, the invisible backplane:

The one who shares the stealth technology is JLaservideo, the technology guru on Youtube. It all started when JLaservideo saw fan messages in the comments section of his video asking him to share the skills to achieve invisibility. As a favorite fan, JLaservideo immediately figured out the stealth technology and shared it.

Revealing the secrets of three popular stealth technologies 1. Video editing

At first, JLaservideo thought of the invisibility cloak in Harry Potter.

As an excellent video editor, he immediately thought that the stealth effect similar to Harry Potter could be achieved through computer special effects.

This method, the principle is very simple, the cost is also the lowest, friends can buy a green screen online 9.9 free delivery, and then use editing software to produce. This is also a common way to make special effects in sci-fi movies.

First of all, we have to use the camera to take a static background picture without characters.

Then, the characters are covered with a green curtain that is convenient for editing software matting.

Finally, the user only needs to dig out the green screen and replace it with the previous background photo on the editing software. In this way, the effect at the beginning of our article is realized.

Of course, this method is more limited. First of all, he can only do it in the form of video. Second, if the position of the camera changes, the effect of the video clip will be directly exposed, as shown below.

Because it is not in line with the effect of real-time stealth in real life, JLaservideo abandoned this method and turned to other technologies to achieve stealth.

2.Convex lens stealth method

In view of the fact that the first method can not be put into life. JLaservideo began to study how to achieve stealth in principle.

First of all, why do we see objects? We can know from junior high school physics that seeing an object is actually seeing the light reflected by it. Thanks to the country's nine-year compulsory education, let me understand this paragraph

So, in the process of light propagation, we can change the path of light propagation in a specific area in some way so that it does not enter our eyeballs, can not we achieve optical invisibility?

In our daily life, the lens that is most exposed to can change the path of light propagation. Lenses are used in everything from magnifying glasses to astronomical telescopes.

Using the characteristics of the convex lens focusing light, when the object appears in the vertical plane of the focus and the position outside the focus path (such as the red area below), the light reflected by the object will not be displayed by the convex lens, thus "optical invisibility" can be realized.

It is not difficult to make such a set of lens optical equipment, and a total of four requirements need to be met:

Two sets of lenses with different focal lengths. Two focal lengths are F1 and two focal lengths are f2.

The distance between the first and second lenses T1 is the sum of the focal lengths of two different lenses: t1=f1+f2, and the distance between the third and fourth lenses is the same.

The second and third lens spacing t _ 2cm _ 2f _ 2* (f1+f2) / (f1-f2).

According to the calculation formula, the lens is placed. At a cost of about 30 yuan, you can also have invisibility within a limited range.

After the production, you can get the following device, of course, the larger the lens, the larger your stealth area!

[photo source: bilibili owner: science brain reactor]

On the other hand, if the lens is too small, the range of invisibility will become too narrow. At the same time, the lens can only achieve stealth in the direction of a fixed viewing angle, and it will be exposed when it moves to the side.

In view of the small stealth space and the limitations of the device, I began to study the most popular stealth device-the stealth shield.

3. Stealth shield

Stealth shield can be said to be a hot product in the stealth world. The use is simple and the effect is outstanding, does not have any study cost, can get started.

The stealth shield still uses the method of changing the transmission of light to achieve stealth.

The secret of stealth lies in these cylindrical convex lenses on the front of the shield.

When using the shield, the light emitted by the object near the rear side of the shield will be refracted and diffused by the shield lens, so that the light that can enter the human eye becomes very little, not enough to image, and finally achieve the purpose of invisibility.

Friends who do not understand can understand with the help of the following picture of the soul. The light from the purple ball is directly refracted into multiple parts, which is no longer enough for imaging.

Similarly, if a laser pointer is used to illuminate the shield from the front, the light gathered in a beam is directly refracted into strips of "bulk" light.

There is still a problem with such a shield, that is, the texture direction of the cylindrical lens is fixed. Once the shield changes from vertical to horizontal, and the refractive index of the light decreases, we can still observe the objects behind the shield.

After discovering the disadvantages of this stealthy shield, JLaservideo fiddled around with the shield at will, and the effect was not satisfactory all the time.

Until he had an idea, picked up the previous photo and overlapped it with the background, he began to have a new idea.

Inspired by the perfect overlap between the photo and the background, JLaservideo decided to use a camera and display screen to create his own stealth device.

The idea of using the code as glue to combine the camera and the display screen to achieve invisibility this time is very simple: record the photo in front of the body with the camera, and then project it to the display screen on the back in real time, so that what you see is the scene in front of me, so you can be invisible. (I can do this, and I can do it, too.)

Editor, I'm an activist, so let's get started!

Emmmmm, there seems to be something wrong with something.

What I need is that the picture displayed on the screen perfectly overlaps with the vacant piece in the field of view, so that the invisibility will not be revealed! But the pictures displayed on this phone are all wrong. They make a fool of themselves.

Go and see how the author deals with this problem, and let's study together.

Boy, after a small class by the author, the editor became enlightened. It turns out that in order to connect the picture displayed on the screen with the picture observed by the human eye, we also need to deal with something called the parallax effect.

Dealing with the parallax effect requires the equipment to crop the picture, or the camera can match the focus of the human eye in real time. Obviously, it is more convenient to crop the picture. After all, no camera can switch the focus in real time to match the eyes that will appear anywhere.

JLaservideo decided not to be so reckless this time, first experimenting with the pre-steps to solve the parallax effect on his mobile phone: let the device know where the human eye is, making it easier for the program to cut your size correctly.

Through the program, the author realizes that the front camera can accurately capture the position of human eyes, and the video can follow the rotation of human eyes with 3D effect.

Then JLaservideo began to transfer cameras and programs to laptops, testing them while making adjustments.

After the program is imported into the computer, the face tracking function test is normal, the real machine test results to see.

This is a direct use of the computer to perform the famous "human body separation" in the magic world. As the camera used is a wide-angle camera, there is still a sense of separation between the screen display and the actual picture, which needs to be re-optimized.

Faced with this situation, JLaservideo said he was not proficient in programming. So he consulted Augmented Startups, an expert blogger in the field of visual algorithms on the tubing.

Under the guidance of experts, the screen of the stealth display screen begins to match the visual angle of the human eye, and the preliminary construction of the stealth display screen equipment is completed.

Why is it a preliminary completion? Because JLaservideo believes that the screen now displays a 2D picture, which is so fake that people can see the problem at a glance.

He began to think about how to make the picture more realistic, adding multiple cameras to the back of the display screen, and using multi-position photos to synthesize 3D pictures can make the picture look realistic, but the cost is too high and the power consumption increases sharply, which obviously does not accord with the original intention of the design.

So he began to look for ways to achieve 3D effects on the 2D plane. After a lot of search work, the popular 2D-to-3D special effects on short videos have entered my brother's eye.

The method was provided by teams from Virginia Institute of Technology and National Tsinghua University. It can provide a way to convert a single RGB-D input image into 3D photos, and the layering of the front, middle and back scenes can also make the 3D effects more realistic than ordinary 3D effects.

It's amazing. Look at hundreds of millions of eyes again.

After applying the method of 2D to 3D to the "stealth display screen", my brother's stealth device can be said to have been basically completed. Naked eye observation is almost indistinguishable from the real situation.

This stealthy display screen will follow the changes in the field of vision of the people in front of you and project the picture behind the screen to the display screen to achieve the stealth of the people behind the display screen!

At this point, I'm going to start polishing the details of the equipment. For example, first get rid of the big black box that is a nuisance.

After a period of clanking operation, the younger brother successfully removed the frame of the display screen and destroyed the display screen.

What if I break it? Buy another one, this time buy an OLED display, more advanced, and the OLED TV screen can also be rolled up, the effect must be better!

The result. Little brother succeeded in reducing his wallet by $500and harvesting a dead OLED TV. It can only be blamed that he likes to pick up the screen and roll it up too much.

Two televisions cost JLaservideo more than $1000, which made the wallet a little shrunken. He is going to be conservative and stop dismantling the TV.

But if you don't take apart the TV, you have to hide the frame. Is there anything you can do? He suddenly thought of the invisibility shield he had given up. He can wrap the TV with an invisibility shield, which can make the frame disappear and eliminate the reflection of the screen!

Then, the little brother wrapped the stealth display screen with an invisible shield.

How to say, the appearance is a bit cold, but at least the frame of the display screen "invisible" off, less money can only make do with it.

The next step is to wander around with this stealthy display screen and experience the joy of invisibility.

The effect of the stealth display screen is still good. But the invisibility shield wrapped in the display screen is really out of class, and it even makes the picture look chromatic aberration.

But kids, don't worry, it's because the little brother is short of money and can't help it. In South Korea, there is an endless building that is not short of money, and endless buildings also like to be invisible. It uses the same scheme, but costs more money.

The whole building is full of display screens, and then the back-to-people side of the building is projected onto the front screen from any point of view, and the whole building looks invisible! But the building is so expensive that it is still under construction. Be sure to have a look at it when it is finished!

Finally, if you are interested in the original video link, you can also watch the original video.

Video link: https://www.youtube.com/ watch?v=K2XMuj3LimI

2D to 3D Code Link: https://shihmengli.github.io/ 3D-Photo-Inpainting/

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.