Straighten the arm straight forward and lift your thumb. Close your left eye, right eye, thumb, and target to form a straight line. Close your right eye and open your left eye. At this time, remember the left eye and your thumb to extend the right side of the straight line target. The distance between that point and the goal is multiplied by 10, which is the approximate distance you get to the goal. give a thumbs up. The arm rests its gaze through the tip of the finger and is about 120 mils from the horizontal. Look at the target height to estimate how close the two angles of the line of sight through the top of the target and the bottom of the target are, and multiply the target height by the density ( Based on experience) is the target distance

For example, the Japanese army is about 1.5 meters tall, and the line of sight is about 100 mils from the top of its head and feet, and the distance is 150 meters. Usually, the length of some objects is a known quantity, such as cars, houses, etc. How much angle is occupied in the visual inspection (using the secret bit in military measurement) can be calculated from the distance.

The number of ciphers in the range covered by the thumb that is erected after the arm is stretched is fixed, and thus the reference value can be obtained by referring to the target to be measured. After conversion, approximate data of distance can be obtained. The secret place is a circle divided into 6,000 copies. Each one is a secret place. There is also a right hand. Close your left eye and aim at an object. Let him just stare at the left side of your thumb. Do not change your eyes. You will find that the object is beating a certain distance. According to the object's visual width, the beat width, the ratio is multiplied by 50. It is about the distance. There is also accumulated experience. The cipher density calculation is also the approximate distance calculated by the actual number of ciphertexts on your hand.

In theory, the arm is straightened and the thumb is erected. The similarity is calculated based on the distance from the eye to the thumb (about the length of the arm), the length of the thumb and the height of the measured object. However, in fact, when using this skill, it is basically based on experience, and it takes a long time to master it. Moreover, to correct the problem, finger distance measurement is mostly used for rough determination of marching and artillery positioning, and is compulsory for each soldier. The sniper rarely uses his finger to measure the distance. Since the finger is to be measured and the arm is straightened, it is easy to expose himself, and the sniper directly uses the visual inspection. Finger distance measurement can generally estimate 2-4 kilometers (applicable to objects, such as houses, trees, etc.). Experienced soldiers have an error of no more than 200 meters. Visual observation is usually used to estimate the distance within one kilometer. The error is 50 meters. Ili. Both finger distance measurement and visual measurement require long-term practice. It is also necessary to understand the size of general objects and their visual size at different distances, and to be able to skillfully use a known reference object for comparison. If you can practice hard, I believe you will succeed.

The “Thumbnail Ranging Method” is based on the hypothetical trigonometric function to measure the hypothetical distance. We have a target of N meters and measure our distance to the target: 1. We hold our right arm horizontally, fist with the right hand and raise the thumb 2. Use the right eye (left eye closed) to overlap the left side of the thumb with the target in a straight line; 3, the right arm and thumb do not move, close the right eye, and then use the left eye to observe the left side of the thumb, you will find the edge Leave the distance to the right of the target; 4. Estimate this distance (this can also be measured), and set this distance to 10, which is the approximate distance from the target.

Also attached to the Chinese and American troops commonly used in human eye distance measurement (jumping method) Legend of the Chinese army and police snipers generally use the method of jumping is eye-catching: right fist clenched, thumb up, stretch out the right arm, Close your left eye and observe the target with your right eye on one side of your thumb. While maintaining your posture, close your right eye, and use your left eye to observe another reference on the same side of your thumb—reference and target. The distance between them is multiplied by 10, which is the actual distance between you and the target. The U.S. military is a bit similar: the right fist clenches, the thumb lays flat, stretches out the right arm, closes the left eye, and just observes the target with the right eye on the upper side of the thumb. If the goal just crosses one step, you are 100 yards from the target. If the goal happens to be two steps, then you are 200 yards away from the target.......... Other visual inspections based on the object are based on visual acuity, target clarity, and practical experience to determine the distance. The basic methods of visual distance measurement are comparison and judgment methods.

(l) Comparison method. It is to compare the distance to be measured with a certain known distance (such as the pole distance, the measured distance or the familiar basic distance of 100 meters, 200 meters, 500 meters, etc.) to find the distance. It is also possible to halve or divide the distance to be measured into several segments, compare segments, and calculate the total length. (2) Judgment method. It is based on the clarity of the target to determine the distance. In the normal vision and weather conditions, the target distance can be distinguished by referring to the following table. However, due to the different eyesight of each person, the use of this form should be based on their own experience.

Distance (m) Target clarity

100 Face features, Hand Joints, Infantry Firearms External Parts Visible 150-170 Clothes Buttons, Kettles, Minor parts of equipment visible 200 Roof tiles, Leaves, Wires Wire visible 250-300 Visible seams, Tiles The number of grooves; the facial features are unclear, the color of the clothes can be divided into 400. The face is unclear, the head and shoulders can be divided into 500. See the switch, the window to see the grid, tile trenches can not be separated; the head and shoulders are not clear, men and women can be divided into 700 Tile surface, window see lining, pedestrians left and right leg points, elbows can not tell the 1000 clear outline of the house tiles chaos, the door into a box window lining eliminate; the body up and down the general rough 1500 tile surface light, window into a hole; Little black spots, action can not distinguish 2000 Windows is a shadow, the door into a hole; people into a small black point, the action can not tell the 3000 houses blurred, the door is difficult to distinguish, the room chimney is also visible

Measuring a person with a long arm has a pair of arms. If you ask him: How long is your arm? He may shake his head and say no. If you ask “arm length” what is going on? I am afraid it will be even more unanswerable. This is because he still does not know his arm can measure distance.

In fact, when you say it, the long arm of the arm is a pencil (or wooden strip) with a dividing plan. However, when combined with the arm, it becomes a very flexible and convenient ranging "instrument". The division on the pencil is based on the circumscribing of each person's arm length (the distance from the arm to the mouth of the tiger's mouth), so call it the long ruler. For example, if someone's arm is 60 centimeters long, then one leg on the long ruler is 6 millimeters. With the arm length, you can use the long arm to measure the distance as long as you know the size of the target in advance. How is the distance calculated? As already stated, each division on the long arm of the arm is one-hundredth of the length of the arm. If the height (or width) of the target occupies one division, it is also just the distance. One percent, accounting for two divisions, is 2%. In this way, based on the similarity of similar triangles, distance: target height (space) = 100 (arm length): number of strokes (arm length), you can come to the formula for distance: Distance = height (interval) × 100 The number of divisions, for example: Measured at intervals in front of the telephone pole, about 5 divisions, we know that the general telephone pole spacing is 50 meters, then the distance to the pole is: 50 meters x 100 = 5000 meters.

If you do not know the width (or height) of the object, can you measure the distance with the long arm of the arm? Or you can, but you must create a known distance condition before you can calculate the distance. When you observe the division of various objects with a long arm, you will find such a situation: When you observe the distance of an object (or at a height of 0, the closer you are to the object, the more the number of divisions is measured; otherwise, the distance from the object The farther away, the less the number of measured zonings.According to this situation, we can measure the size of the two scribes for the same target in the two positions, and measure the distance between the two observation positions. With these three known numbers, the distance can be calculated according to the following formula: Distance = forward (or backward) distance × small sub-divisional large sub-division - for example, a certain engineering unit, in order to complete the bridging task, first The scouts were sent to measure the width of the river. The scout first measured the distance between the two objects on the bank of the river by eight long strokes on the river bank. Then the distance between the two ground objects was measured at 30 meters and it was 5 points. Divide these values ​​into the formula and calculate the river width as: 30×5=150 meters

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