What is the principle of the seemingly fast moving advertisements outside the subway car?

It's the same principle as the previous cartoons you watched.

When I was a child, cartoons were made up of many images with only minor differences being shown together in quick succession, and then the characters moved.

We were in the carriage and saw fast-moving advertisements outside the carriage, which were actually lined up by n identical advertisements. That way, when you move, you'll always see the same picture. If the train is running too fast and the time it takes to pass a billboard is also very fast, only hundredths of a second, our visual breakpoints will not be recognized.

I can't recognize movement, so what I see is a basically fixed picture.

If, our subway passes a certain length of billboard at a slightly slower speed, then people will not be able to see anything clearly, and what they will see is a flash of bright light, and the content is basically paste. Just like when a camera takes a picture, it uses a relatively slow shutter speed, and when it shoots a moving person, it will produce a series of tail-like shadows, from the distance it starts to move to the point where it finally stops, and the middle section is a blurred human shape.

In fact, it is a clever use of time.

Like billboards on highways, they are generally large enough that people can see them from a great distance, and after a few seconds of driving, people can still see them until they pass this billboard. It's about using this short few seconds to make people remember what's on the billboard.

If the billboards next to the subway are all the same color, only red, then we see the same thing, and a fixed red will always flash in front of us. Just as nothing has changed, there is no difference from our usual visual habits.

Do you want to say that when you take the subway, you see the advertisements outside and seem to be moving backwards quickly?

In fact, this phenomenon is very common, and it can be easily solved by using high school knowledge.

In high school physics class, we start by learning about the motion of objects. So what is exercise? In Newton's view, there is relative and absolute movement.

And the phenomenon you are talking about is called relative motion. For example, if you see the sun rising in the east and setting in the west, of course you know that the sun is not moving, it is the earth that is moving, and the earth is revolving around the sun. But when you look at the sun, you still think it's moving, why is that?

In fact, you are standing on the earth, you are using the earth as a reference, and you are stationary relative to the reference, so it feels like the sun is moving. This is relative motion. For example, if you are walking on the road, you will feel that you are moving forward, and when you turn your head to look at the nearby trees, you will feel that the trees are moving backwards.

This is also the result of the different references you get. When you feel like you're moving forward, you're using the ground as a reference. You think that the ground is not moving, so you are moving forward, and when you look at the tree next to you, you are using yourself as a reference, and you think that you are not moving, and the tree is moving backwards.

This explains why you feel like the billboard outside the car is moving backwards in a subway car.

With that said, I would like to talk about absolute motion as opposed to relative motion. Newton's view, he believed that there is a kind of thing that absolutely does not understand matter, called the ether. He believed that ether is an invisible and intangible substance, permeating every corner of the world, it is absolutely immovable, and all matter has no movement based on it.

It's an absolute sport.

In fact, after Newton, there was a more intense discussion about whether there was such a substance as ether. The famous scientist Albert Einstein's treatise, the theory of relativity, denied the existence of the ether. In his general theory of relativity, he states that the laws of physics are the same in any frame of reference.

We don't use the theory of relativity in life, and for the above phenomenon, as long as we know what relative motion is, this is enough to explain this phenomenon.

Two aspects are comprehensively explained: visual persistence and relative motion.

Let's start with what visual persistence is. Visual persistence is also known as the "afterglow effect", which refers to the human eye when observing the scene, the light signal is transmitted to the cranial nerve, and it takes a short period of time to pass, and the visual image does not disappear immediately after the end of the action of light, and this residual vision is called "posterior image", and this phenomenon of vision is called "visual retention". The movies and television cartoons we usually watch use this principle to make use of this principle, and the moving pictures are actually connected one by one, and the frame rate is actually the number of static pictures contained in a one-second time dynamic picture.

Due to the existence of the visual retention effect, we have seen a picture, and when the human brain has not had time to react and still leave an impression, it has already begun to display the next picture, and the next picture will appear again when the picture of the upper clothes has not yet been impressed, so that we seem to form a coherent picture. Animation is the best understood visual persistence effect of film and television works. Referring to a series of works with a strong Chinese ink painting style produced by Shanghai Fine Arts Film Studio, such as the tadpole looking for his mother, etc., they are all coherent after the artist has painted one by one, in fact, every frame we look at is an ink painting painted by the artist.

Motion picture film. <>

The little tadpole looking for the stills of his mother.

Let's talk about another principle, which is relative motion. I believe this big guy has been exposed to it in high school, what is relative motion? The motion of the object is relative.

The position of one object relative to another object changes with time, then this object is in motion towards another object, and this object is in relative motion. If their positions do not change with time, the object is at relative rest. To put it simply, you move it and you move, you are relatively stationary, you move it and it doesn't move, you move relative to it in motion.

Motion is relative, and it cannot be said that an object is in motion alone.

Demonstrate relative motion.

So let's get back to the problem. When the subway car is moving at high speed, you and the car are relatively stationary, but in the process of moving with the subway car at high speed, you are moving at high speed relative to the subway billboard. So in the process of you walking forward, the subway billboard is moving backwards, which can also be understood as if you don't move, and the subway billboard is moving backwards away from you quickly.

Coupled with the visual persistence effect we just mentioned, in the process of rapid movement of billboards, in fact, our human brains can't react. So it looks like billboards are always fast and long. So in the subway, you feel like the billboard is moving fast.

Well, just sauce.

Isn't this the relativity of motion, I studied physics in junior high school, so it looks like those things are moving.

There are two principles:

1. Set up a super long screen in the subway tunnel, when the car moves, it senses the screen, and the screen displays animated advertisements in real time.

By continuously installing 400 to 800 pieces on the tunnel wall of 200 to 800 meters, by limiting the viewing angle of each single picture installed on the tunnel wall, when the train is moving at high speed, the pictures installed on the tunnel wall are quickly flashed one by one in a relatively fixed position with the passengers, so that the passengers can feel the animation effect.

The human eye will see 24 frames per second as continuous, so the principle is similar to that of a cartoon or a movie.

2. Using the principle of "visual retention", when the picture exceeds 24 frames per second, people feel that the picture is continuous when they meet in the morning, and the animation of turning books when I was a child is this principle.

On the inner wall of the tunnel are vertical emitters, each of which is nearly 1 meter high, and nearly 600 LEDs are distributed on it as a column of pixels, with the two emitters spaced about one meter apart.

This kind of "animation" should be set in a section of the subway speed is relatively stable, when the train is stationary, only the light points of various colors on each pillar of light can be seen, when the train moves rapidly, the principle of "visual persistence" (1 24 seconds) can be used to form a dynamic picture. The effect of frame scanning is similar to that of a TV.

If the speed is slightly faster or slower, the person on the train will feel that the screen is moving slowly forward or backward.

Summary. Hello dear, according to your question, the principle of moving forward in subway advertising is to use the phenomenon of visual persistence. When the human eye observes a scene, because the brain needs time to process the information transmitted by the visual input, when the eye follows a moving object, the eye does not actually observe every frame of the object continuously, but records several images at different times in a flash.

These images remain in the brain, creating the illusion that objects are moving continuously. Subway advertisements take advantage of this visual persistence phenomenon to set up a moving background behind the advertisement, such as a sports scene or scenery, so that the advertisement looks as if it is moving, attracting more attention and comfort. The advertising engineer will design the speed of the movement of the advertisement and the image according to the speed of the passenger in the subway and the time observed, so as to achieve the optimal effect.

Hello dear, according to your question, the principle of moving forward in subway advertising is to use the phenomenon of visual persistence. When the human eye observes a scene, because Yamato takes time to process the information transmitted by the visual input, when the eye follows a moving object, the eye does not actually observe every frame of the object continuously, but records several images at different times in a split second. These images remain in the brain, creating the illusion that objects are moving continuously.

Subway advertisements take advantage of this visual persistence phenomenon to set up a moving background behind the advertisement, such as a sports scene or scenery, so that the advertisement looks as if it is moving, attracting more attention and comfort. The advertising engineer will design the speed of the advertisement and the source shed to guess the movement speed of the image according to the speed of passengers in the subway and the time observed, so as to achieve the best effect.

Are the dynamic ads on the subway moving in that direction when the subway is accelerating?

Hello, according to your question, when the subway car accelerates, the dynamic advertisement on the subway usually moves to the rear of the car, that is, it looks like the boy is moving backwards. This is because when the subway accelerates, passengers move backwards due to inertia, causing the line of sight to extend backwards. In order to avoid causing discomfort and dizziness to passengers, the dynamic effect of advertising pants burning will also follow the movement of the carriage and maintain the direction of backward movement, so as to maintain a relatively stable picture.

When the subway slows down and stops, the direction of movement of the advertisement also changes, that is, it moves forward, which is to maintain the visual stability and continuity of the advertisement. Usually, the advertising designer will design and adjust the advertising screen according to the parameters such as the running speed and acceleration of the subway to achieve the best visual effect and marketing effect.

Summary. Hello dear, here is the teacher's answer <>

The principle of moving forward in subway advertising is that during the operation of the subway train, there will be an airflow effect, that is, when the train is moving, an airflow will be formed in front of the train, and the airflow will push the air in the carriage backwards, thus producing a forward thrust. The movement of subway advertisements takes advantage of this airflow effect, which fixes the billboard to the track inside the subway car, and when the train moves, the airflow pushes the billboard forward, thus realizing the movement of the advertisement. In addition, the movement of subway advertising also involves the support of some mechanical devices, such as fixing some wheels under the billboard, and the wheels are in contact with the track, so that the billboard can move smoothly along the track under the impetus of the air flow.

At the same time, there are also some electronic control systems, which can control the speed and stop position of the billboard, so as to achieve the accurate display of advertising. The movement of subway advertising is realized under the control of an electronic control system using the airflow effect generated by the movement of the train and the support of some mechanical devices.

The principle of moving forward in subway advertising.

Hello dear, here is the teacher's answer <>

The principle of moving forward in subway advertising is that during the operation of the subway train, there will be an airflow effect, that is, when the train is moving, an airflow will be formed in front of the train, and the airflow will push the air in the carriage backwards, thus producing a forward thrust. The movement of subway advertisements takes advantage of this airflow effect, which fixes the billboard to the track inside the subway car, and when the train moves, the airflow pushes the billboard forward, thus realizing the movement of the advertisement. In addition, the movement of subway advertisements also involves the support of some mechanical devices, such as fixing some wheels under the billboards, and the wheels are in contact with the tracks, so that the billboards can move smoothly along the tracks under the impetus of the air flow of filial piety.

At the same time, there are also some electronic control systems that can control the speed and stop position of the billboard, so as to achieve the accurate display of the advertisement. The movement of subway advertising is realized under the control of an electronic control system using the airflow effect generated by the movement of the train and the support of some mechanical devices.

Are the dynamic ads on the subway moving in that direction when the subway is accelerating?

Hello dear, the dynamic draft on the subway will move backwards when the subway accelerates. When the subway accelerates, the air in the carriage flows backwards, creating a backward airflow effect that pushes objects in the carriage backwards. Therefore, dynamic ads on the subway will be affected by this backward airflow effect when the subway accelerates, and move backwards cautiously.