What are the ranging methods?

Ranging is the most useful in the battlefield, the most important in simple surveying and mapping, with the most methods. Here, we can only choose some of the simplest and most practical ones to talk about.

1. Step measurement

Everyone has a convenient ruler, which is very convenient to use. This ruler is our foot.

To measure the distance with your feet, you must first know how big your steps are. There is a range of walking speed. Otherwise, it is inaccurate.

There is a step size in the "queuing rules". March in a hurry, one step is 75 cm, two steps are a complicated step, and a complicated step is one and a half meters; The traveling speed is 120 steps per minute.

Why is it stipulated that the number of steps is 1.5 meters and the pace is 120 steps per minute? This is based on experience. A large number of tests show that an adult's stride is about half the height of his eyes from the ground. For example, the height from the foot root to the eye is 150 cm, and his stride is 75 cm. If you are interested, you may wish to test it yourself.

There is another experience: the number of kilometers we can walk per hour is exactly the same as the number of steps we take every three seconds. For example, if you can walk five steps in three seconds, you can walk five kilometers per hour. If you don't believe me, you can try.

These two experiences are only approximate figures, and they will not be exactly the same for everyone. There is a question of whether the step size is uniform and the speed is consistent. If you want to measure the distance accurately, you should always practice your step size and pace.

How to practice? Doesn't the company practice footwork every day? This is an excellent opportunity to practice step size and speed.

There is another way. On the expressway, every kilometer has a milestone. You can always walk with footsteps, count the steps, look at the time, and repeatedly feel your stride size and speed.

If you master your stride and pace, you will learn to walk. When stepping, you can calculate the distance by remembering the number of steps or the time. For example, knowing that a person's steps are 1.5m, and counting a certain distance is 540 steps, this distance is: 540× 1.5m = 8 10m. If you know that your pace is 54 steps per minute and you have walked 10 minute, you can also calculate the distance as follows: 54× 10=540 steps, 540× 1.5m =8 10 meter. According to the relationship between the number of steps and the number of meters, we simplify this calculation method to one sentence: "The number of steps plus half of the number of steps equals the distance." You can calculate the distance quickly.

2. Appearance inspection

The human eye is a natural measuring "instrument", which can not only see the nose tip close at hand, but also see distant celestial bodies in space. Although you can't measure the distance with your eyes, you can measure it accurately as long as you study hard and practice hard. In our artillery unit, many comrades have developed excellent visual skills. They can accurately measure the distance within a few kilometers in a few seconds, just like a rangefinder.

How to measure the distance of an object with your eyes?

People's vision is relatively stable. With the distance of objects, vision is constantly changing. Close object distance, clear vision, far object distance, blurred vision.

The shape of an object has certain rules, and different objects have different clarity due to different distances. When we practice visual inspection, we should pay attention to observing and understanding the clarity of various objects at different distances. The more you observe, the deeper your impression is, and you can intuitively measure the distance of an object according to the observed shape. For example, a person comes from a distance, 2000 meters away from you, and you see that he is just a black spot; When he is away from you 1000 meters, you can see that his body is generally thick from top to bottom; At 500 meters, the head, shoulders and limbs can be distinguished; At a distance of 200 meters, you can tell their faces, clothes colors and accessories.

This ability to visually measure distance can only be learned by oneself. Other people's experience doesn't fully apply to you. The data listed in the table below are the experience of normal people's naked eye observation under normal circumstances, and are for comrades' reference only.

Clarity of different targets at different distances

Range (meter) resolution Target clarity

100 facial features, hand joints and external parts of infantry guns.

150- 170 buttons, kettles and small parts of equipment.

There are 200 tiles, leaves and wires on the roof.

250-300 walls can see cracks, and tiles can count ditches; Unclear facial features; The colors of clothes, light machine guns and rifles can be divided.

400 faces are unclear, and the head and shoulders can be divided.

500 doors see switches, windows see grids, and tiles are unclear; Head and shoulders are unclear, and men and women can be divided.

700 watt surface into silk; See the window lining; Pedestrians can't tell the difference between legs and elbows.

1000 The outline of the house is clear, the tiles are messy and the doors and windows are square; The human body is generally thick from top to bottom.

1500 ceramic tile has a flat surface and holes in the window; Pedestrians seem to be squirming and can't tell their movements.

2000 windows are shadows and doors are holes; People become small black spots, and they can't tell the difference between stopping and moving.

3,000 houses are blurred, the doors are difficult to separate, and the chimneys on the houses are still visible.

When you are uncertain about judging the distance according to the clarity of the target, you can also compare each other with the known distance from the current location. Only by comparison can you make a judgment. For example, the distance between two poles is generally 50 meters. If there is a pole near the observation target, we can compare the distance between the observed object and the pole, and then make a judgment. When there is no distance comparison in the field, use the familiar basic distances, such as 50m, 100m, 200m, 500m, etc. And after repeated memories and comparisons. If the distance to be measured is long, it can be compared in sections and then the total length can be calculated.

Due to the difference of weather, sunshine, object color, observation position and angle, the resolution of eyes will often be affected, and the distance of visual inspection will also produce errors.

Sunny day: facing the sun, the eyes will be stimulated by light, and the vision will be weakened, making it easy to detect distant objects; If you observe with your back to the sun, your eyes are not stimulated by light, and the object is clearly and brightly illuminated by the sun, which is convenient for measuring the object at a closer distance.

On cloudy days or when the sky is dark in the morning and evening: visibility is weakened, objects appear blurred, and it is easy to detect distant targets.

After rain: the air is fresh, the objects are brightly colored, and it is easy to get close to the target.

It is easy to get close to the target by visual observation on the open terrain, or through the water surface and valley, or from a high place to a low place.

We should explore our own experience through hard practice and repeated experience according to various specific conditions. As the saying goes, "Practice makes perfect". With more practice, deeper experience and rich experience, you can visually measure the distance of objects more accurately.

Measure with a rifle

Semi-automatic rifles, submachine guns and light machine guns in our hands are all weapons to destroy the enemy; However, it has new uses in simple surveying and mapping. It is not only a weapon, but also an excellent ranging "instrument", which is fast and convenient to use. When you shoot at the enemy and aim at it, you can measure the distance, which is very timely and suitable for ruler division and aiming point selection.

How do weapons measure distance?

This is calculated according to the width of the scope that can cover the target, so it is called scope coverage method. The weapons made in the factory have a certain size. For example, the width of the sight is 2mm, and the distance from the eyes to the sight can be directly measured when aiming (for example, the semi-automatic rifle is 74cm). The width of the target (mainly the human body) is generally 50 cm. In this way, according to similar triangles's proportional principle, we can calculate the relationship between the line-of-sight width of various weapons and the width of the target (human body) at different distances. According to the calculation, when the scope is just wide enough to cover a human body, the distance of our army's weapons is 200 meters for semi-automatic rifles, 0/60 meters for submachine guns and 0/70 meters for light machine guns. If you cover half of the human body, it is half of their distance, that is, 100 meters, 80 meters, 85 meters; If half a line of sight can cover a person's body, it is twice their distance, that is, 400 meters, 320 meters and 340 meters. Therefore, as long as you remember that the scope covers the target, you can estimate the distance immediately.

Measure with a compass

The compass can not only indicate from east to west and from north to south, but also tell you the distance to the target.

When designing and manufacturing the compass, the factory has already considered the problem of measuring distance with it. Open the compass and you will immediately find a scene and a door. The width of the tips on both sides of the quasi-constellation is exactly one tenth of the distance from the quasi-constellation to the light gate. Quasi-constellation estimates the decision distance, so it is called "distance estimator".

When measuring the distance, put the compass flat, observe the target through the door and sight with your right eye, remember the width of the light spot with the distance estimator, and then visually observe the width of the light spot and multiply it by 10, which is the distance to the target. If the target is too narrow, you can also aim at half of the evaluator, so multiply it by 20.

For example, the measured enemy tank is about half of the estimated amount, and it is known that the enemy tank is about 7 meters long, so the distance to the tank can be calculated as: 7 meters ×20= 140 meters.

5. Measure with an arm ruler

Everyone has a pair of arms. If you ask him: How long are your arms? He probably shook his head and said he hadn't measured it. If you want to ask again, what is an "arm length ruler"? I'm afraid I can't answer it even more. This is because he doesn't know that his arm can still measure the distance. In fact, to put it bluntly, an arm ruler is a pencil (or a piece of wood) engraved with divisions. But when it is combined with the arm, it becomes a very flexible and convenient ranging "instrument".

The division on the pencil is described by one hundredth of each person's arm length (the distance from the eyes to the thumb), so it is called the arm length ruler. For example, if someone's arm length is 60 cm, then a division on the arm ruler is 6 mm With the arm ruler, as long as the size of the target is known in advance, the distance can be measured with the arm ruler.

So how is the distance calculated? As mentioned above, each partition on the arm length ruler is 1% of the arm length, and if the height (or width) of the target occupies one partition, it is exactly 1% of the distance, which occupies two partitions, it is 2%. In this way, according to similar triangles's proportional principle, distance: target height (interval) = 100 (arm length): division number (arm length ruler), the formula for finding the distance can be obtained:

Distance = height (interval) × 100 grid

For example, we measure the distance between a telephone pole in front, which is about five grids. We know that the distance between telephone poles is generally 50 meters, so the distance to the telephone poles is:

50m× 100 = 1000m。