World map measure distance. How to measure distance along a straight line using a topographic map

1.1.Map scales

Map scale shows how many times the length of a line on a map is less than its corresponding length on the ground. It is expressed as a ratio of two numbers. For example, a scale of 1:50,000 means that all terrain lines are depicted on the map with a reduction of 50,000 times, i.e. 1 cm on the map corresponds to 50,000 cm (or 500 m) on the terrain.

Rice. 1. Design of numerical and linear scales on topographic maps and city plans

The scale is indicated under the bottom side of the map frame in digital terms (numerical scale) and in the form of a straight line (linear scale), on the segments of which the corresponding distances on the ground are labeled (Fig. 1). The scale value is also indicated here - the distance in meters (or kilometers) on the ground, corresponding to one centimeter on the map.

It is useful to remember the rule: if you cross out the last two zeros on the right side of the ratio, the remaining number will show how many meters on the ground correspond to 1 cm on the map, i.e. the scale value.

When comparing several scales, the larger one will be the one with the smaller number on the right side of the ratio. Let’s assume that there are maps at scales of 1:25000, 1:50000 and 1:100000 for the same area. Of these, a scale of 1:25,000 will be the largest, and a scale of 1:100,000 will be the smallest.
The larger the scale of the map, the more detailed the terrain is depicted on it. As the scale of the map decreases, the number of terrain details shown on it also decreases.

The detail of the terrain depicted on topographic maps depends on its nature: what less details contains the terrain, the more fully they are displayed on maps of smaller scales.

In our country and many other countries, the main scales for topographic maps are: 1:10000, 1:25000, 1:50000, 1:100000, 1:200000, 1:500000 and 1:1000000.

The maps used by the troops are divided into large-scale, medium-scale and small-scale.

1.2. Measuring straight and curved lines using a map

To determine on a map the distance between terrain points (objects, objects), using a numerical scale, you need to measure on the map the distance between these points in centimeters and multiply the resulting number by the scale value.

Example, on a map of scale 1:25000 we measure with a ruler the distance between the bridge and windmill(Fig. 2); it is equal to 7.3 cm, multiply 250 m by 7.3 and get the required distance; it is equal to 1825 meters (250x7.3=1825).

Rice. 2. Determine the distance between terrain points on the map using a ruler.

A small distance between two points in a straight line is easier to determine using a linear scale (Fig. 3). To do this, a measuring compass is sufficient, the solution of which is equal to the distance between given points on the map, apply it to a linear scale and take a reading in meters or kilometers. In Fig. 3 the measured distance is 1070 m.

Rice. 3. Measuring distances on a map with a measuring compass on a linear scale

Rice. 4. Measuring distances on a map with a compass along winding lines

Large distances between points along straight lines are usually measured using a long ruler or measuring compass.

In the first case, a numerical scale is used to determine the distance on the map using a ruler (see Fig. 2).

In the second case, the “step” solution of the measuring compass is set so that it corresponds to an integer number of kilometers, and an integer number of “steps” is plotted on the segment measured on the map. The distance that does not fit into the whole number of “steps” of the measuring compass is determined using a linear scale and added to the resulting number of kilometers.

In the same way, distances are measured along winding lines (Fig. 4). In this case, the “step” of the measuring compass should be taken 0.5 or 1 cm, depending on the length and degree of tortuosity of the line being measured.

Rice. 5. Distance measurements with a curvimeter

To determine the length of a route on a map, a special device is used, called a curvimeter (Fig. 5), which is especially convenient for measuring winding and long lines.

The device has a wheel, which is connected by a gear system to an arrow.

When measuring distance with a curvimeter, you need to set its needle to division 99. Holding the curvimeter in a vertical position, move it along the line being measured, without lifting it from the map along the route so that the scale readings increase. Having reached the end point, count the measured distance and multiply it by the denominator of the numerical scale. (In this example, 34x25000=850000, or 8500 m)

1.3. Accuracy of measuring distances on the map. Distance corrections for slope and tortuosity of lines

Accuracy of determining distances on the map depends on the scale of the map, the nature of the measured lines (straight, winding), the chosen measurement method, the terrain and other factors.

The most accurate way to determine the distance on the map is in a straight line.

When measuring distances using a compass or a ruler with millimeter divisions average value measurement errors in flat areas usually do not exceed 0.7-1 mm on the map scale, which is 17.5-25 m for a map of scale 1:25000, 35-50 m for a map of scale 1:50000, 35-50 m for a map of scale 1:100000. 70-100 m.

In mountainous areas with steep slopes, errors will be greater. This is explained by the fact that when surveying a terrain, it is not the length of the lines on the Earth’s surface that is plotted on the map, but the length of the projections of these lines onto the plane.

For example, With a slope steepness of 20° (Fig. 6) and a distance on the ground of 2120 m, its projection onto the plane (distance on the map) is 2000 m, i.e. 120 m less.

It is calculated that with an inclination angle (steepness of the slope) of 20°, the resulting distance measurement result on the map should be increased by 6% (add 6 m per 100 m), with an inclination angle of 30° - by 15%, and with an angle of 40° - by 23 %.

Rice. 6. Projection of the length of the slope onto a plane (map)

When determining the length of a route on a map, it should be taken into account that road distances measured on the map using a compass or curvimeter are in most cases shorter than the actual distances.

This is explained not only by the presence of ups and downs on the roads, but also by some generalization of road convolutions on maps.

Therefore, the result of measuring the length of the route obtained from the map should, taking into account the nature of the terrain and the scale of the map, be multiplied by the coefficient indicated in the table.

1.4. The simplest ways to measure areas on a map

An approximate estimate of the size of the areas is made by eye using the squares of the kilometer grid available on the map. Each grid square of maps of scales 1:10000 - 1:50000 on the ground corresponds to 1 km2, a grid square of maps of scale 1 : 100000 - 4 km2, the square of the map grid at a scale of 1:200000 - 16 km2.

Areas are measured more accurately palette, which is a sheet transparent plastic with a grid of squares with a side of 10 mm applied to it (depending on the map scale and the required measurement accuracy).

Having applied such a palette to the measured object on the map, they first count from it the number of squares that completely fit inside the contour of the object, and then the number of squares intersected by the contour of the object. We take each of the incomplete squares as half a square. As a result of multiplying the area of ​​one square by the sum of squares, the area of ​​the object is obtained.

Using squares of scales 1:25000 and 1:50000, it is convenient to measure the areas of small areas with an officer’s ruler, which has special cutouts rectangular shape. The areas of these rectangles (in hectares) are indicated on the ruler for each gharta scale.

2. Azimuths and directional angle. Magnetic declination, convergence of meridians and direction correction

True azimuth(Au) - horizontal angle, measured clockwise from 0° to 360° between the northern direction of the true meridian of a given point and the direction to the object (see Fig. 7).

Magnetic azimuth(Am) - horizontal angle, measured clockwise from 0e to 360° between the northern direction of the magnetic meridian of a given point and the direction to the object.

Directional angle(α; DU) - horizontal angle, measured clockwise from 0° to 360° between the northern direction of the vertical grid line of a given point and the direction to the object.

Magnetic declination(δ; Sk) - the angle between the northern direction of the true and magnetic meridians at a given point.

If the magnetic needle deviates from the true meridian to the east, then the declination is eastern (counted with a + sign); if the magnetic needle deviates to the west, then the declination is western (counted with a - sign).

Rice. 7. Angles, directions and their relationships on the map

Meridian convergence(γ; Sat) - the angle between the northern direction of the true meridian and the vertical grid line at a given point. When the grid line deviates to the east, the convergence of the meridian is eastern (counted with a + sign), when the grid line deviates to the west - western (counted with a - sign).

Direction correction(PN) - the angle between the northern direction of the vertical grid line and the direction of the magnetic meridian. It is equal to the algebraic difference between the magnetic declination and the convergence of the meridians:

3. Measuring and plotting directional angles on the map. Transition from directional angle to magnetic azimuth and back

On the ground using a compass (compass) to measure magnetic azimuths directions, from which they then move to directional angles.

On the map on the contrary, they measure directional angles and from them they move on to magnetic azimuths of directions on the ground.

Rice. 8. Changing directional angles on the map with a protractor

Directional angles on the map are measured with a protractor or chord angle meter.

Measuring directional angles with a protractor is carried out in the following sequence:

• the landmark at which the directional angle is measured is connected by a straight line to the standing point so that this straight line is greater than the radius of the protractor and intersects at least one vertical line of the coordinate grid;
• align the center of the protractor with the intersection point, as shown in Fig. 8 and count the value of the directional angle using the protractor. In our example, the directional angle from point A to point B is 274° (Fig. 8, a), and from point A to point C is 65° (Fig. 8, b).

In practice, there is often a need to determine the magnetic AM from a known directional angle ά, or, conversely, the angle ά from a known magnetic azimuth.

Transition from directional angle to magnetic azimuth and back

The transition from the directional angle to the magnetic azimuth and back is carried out when on the ground it is necessary to use a compass (compass) to find the direction whose directional angle is measured on the map, or vice versa, when it is necessary to put on the map the direction whose magnetic azimuth is measured on the ground with using a compass.

To solve this problem, it is necessary to know the deviation of the magnetic meridian of a given point from the vertical kilometer line. This value is called the direction correction (DC).

Rice. 10. Determination of the correction for the transition from directional angle to magnetic azimuth and back

The direction correction and its constituent angles - the convergence of meridians and magnetic declination are indicated on the map under the southern side of the frame in the form of a diagram that looks like that shown in Fig. 9.

Meridian convergence(g) - the angle between the true meridian of a point and the vertical kilometer line depends on the distance of this point from the axial meridian of the zone and can have a value from 0 to ±3°. The diagram shows the average for of this sheet maps of convergence of meridians.

Magnetic declination(d) - the angle between the true and magnetic meridians is indicated on the diagram for the year the map was taken (updated). The text placed next to the diagram provides information about the direction and magnitude of the annual change in magnetic declination.

To avoid errors in determining the magnitude and sign of the direction correction, the following technique is recommended.

From the tops of the corners in the diagram (Fig. 10), draw an arbitrary direction OM and designate with arcs the directional angle ά and the magnetic azimuth Am of this direction. Then it will be immediately clear what the magnitude and sign of the direction correction are.

If, for example, ά = 97°12", then Am = 97°12" - (2°10"+10°15") = 84°47 " .

4. Preparation according to the data map for movement in azimuths

Movement in azimuths- This is the main way to navigate in areas poor in landmarks, especially at night and with limited visibility.

Its essence lies in maintaining on the ground the directions specified by magnetic azimuths and the distances determined on the map between the turning points of the intended route. Directions of movement are determined using a compass, distances are measured in steps or using a speedometer.

The initial data for movement along azimuths (magnetic azimuths and distances) are determined from the map, and the time of movement is determined according to the standard and drawn up in the form of a diagram (Fig. 11) or entered into a table (Table 1). Data in this form is given to commanders who do not have topographic maps. If the commander has his own working map, then he draws up the initial data for moving along azimuths directly on the working map.

Rice. 11. Scheme for movement in azimuth

The route of movement along azimuths is chosen taking into account the terrain's passability, its protective and camouflage properties, so that in a combat situation it provides a quick and covert exit to the specified point.

The route usually includes roads, clearings and other linear landmarks that make it easier to maintain the direction of movement. Turning points are chosen at landmarks that are easily recognizable on the ground (for example, tower-type buildings, road intersections, bridges, overpasses, geodetic points, etc.).

It has been experimentally established that the distances between landmarks at turning points of the route should not exceed 1 km when traveling on foot during the day, and 6–10 km when traveling by car.

For driving at night, landmarks are marked along the route more often.

To ensure a secret exit to a specified point, the route is marked along hollows, tracts of vegetation and other objects that provide camouflage of movement. Avoid traveling on high ridges and open areas.

The distances between landmarks chosen along the route at turning points are measured along straight lines using a measuring compass and a linear scale, or, perhaps more accurately, with a ruler with millimeter divisions. If the route is planned along a hilly (mountainous) area, then a correction for the relief is introduced into the distances measured on the map.

Table 1

5. Compliance with standards

To determine on a map the distance between terrain points (objects, objects), using a numerical scale, you need to measure on the map the distance between these points in centimeters and multiply the resulting number by the scale value (Fig. 20).

Rice. 20. Measuring distances on a map with a measuring compass

on a linear scale

For example, on a map at a scale of 1:50,000 (scale value 500 m), the distance between two landmarks is 4.2 cm.

Therefore, the required distance between these landmarks on the ground will be equal to 4.2 500 = 2100 m.

A small distance between two points in a straight line is easier to determine using a linear scale (see Fig. 20). To do this, it is enough to apply a measuring compass, the opening of which is equal to the distance between given points on the map, to a linear scale and take a reading in meters or kilometers. In Fig. 20 the measured distance is 1250 m.

Large distances between points along straight lines are usually measured using a long ruler or measuring compass. In the first case, a numerical scale is used to determine the distance on the map using a ruler. In the second case, the opening (“step”) of the measuring compass is set so that it corresponds to an integer number of kilometers, and an integer number of “steps” are plotted on the segment measured on the map. The distance that does not fit into the whole number of “steps” of the measuring compass is determined using a linear scale and added to the resulting number of kilometers.

In this way, distances are measured along winding lines. In this case, the “step” of the measuring compass should be 0.5 or 1 cm, depending on the length and degree of tortuosity of the line being measured (Fig. 21).

Rice. 21. Measuring distances along curved lines

To determine the length of a route on a map, a special device called a curvimeter is used. It is convenient for measuring curved and long lines. The device has a wheel, which is connected by a gear system to an arrow. When measuring distance with a curvimeter, you need to set its needle to the zero division, and then roll the wheel along the route so that the scale readings increase. The resulting reading in centimeters is multiplied by the scale value and the distance on the ground is obtained.

The accuracy of determining distances on a map depends on the scale of the map, the nature of the measured lines (straight, winding), the chosen method of measuring the terrain and other factors.

The most accurate way to determine the distance on the map is in a straight line. When measuring distances using a measuring compass or a ruler with millimeter divisions, the average measurement error on flat areas of the terrain usually does not exceed 0.5–1 mm on the map scale, which is 12.5–25 m for a map of scale 1: 25,000 , scale 1: 50,000 – 25–50 m, scale 1: 100,000 – 50–100 m. In mountainous areas with steep slopes, errors will be greater. This is explained by the fact that when surveying a terrain, it is not the length of the lines on the Earth’s surface that is plotted on the map, but the length of the projections of these lines onto the plane.

With a slope steepness of 20° and a distance on the ground of 2120 m, its projection onto the plane (distance on the map) is 2000 m, i.e. 120 m less. It is calculated that with an inclination angle (steepness of the slope) of 20°, the resulting distance measurement result on the map should be increased by 6% (add 6 m per 100 m), with an inclination angle of 30° - by 15%, and with an angle of 40° - by 23 %.

When determining the length of a route on a map, it should be taken into account that road distances measured on the map using a compass or curvimeter are shorter than the actual distances. This is explained not only by the presence of ups and downs on the roads, but also by some generalization of road convolutions on maps. Therefore, the result of measuring the length of the route obtained from the map should, taking into account the nature of the terrain and the scale of the map, be multiplied by the coefficient indicated in the table. 3.

Measure the corresponding segment using a ruler. It is preferable that it be made from as thin a material as possible. sheet material. If the surface on which it is spread is not flat, a tailor's meter will help. And if you don’t have a thin ruler, and if you don’t mind piercing the card, it’s convenient to use a compass for measuring, preferably with two needles. Then you can transfer it to graph paper and measure the length of the segment along it.

Roads between two points are rarely straight. A convenient device - a curvimeter - will help you measure the length of the line. To use it, first rotate the roller to align the arrow with zero. If the curvimeter is electronic, it is not necessary to set it to zero manually - just press the reset button. Holding the roller, press it to the starting point of the segment so that the mark on the body (located above the roller) points directly to this point. Then move the roller along the line until the mark is aligned with the end point. Read the testimony. Please note that some curvimeters have two scales, one of which is graduated in centimeters, and the other in inches.

Find the scale indicator on the map - it is usually located in the lower right corner. Sometimes this indicator is a piece of calibrated length, next to which it is indicated what distance it corresponds to. Measure the length of this segment with a ruler. If it turns out, for example, that it has a length of 4 centimeters, and next to it it is indicated that it corresponds to 200 meters, divide the second number by the first, and you will find out that everyone on the map corresponds to 50 meters on the ground. On some, instead of a segment, there is a ready-made phrase, which may look, for example, as follows: “There are 150 meters in one centimeter.” The scale can also be specified as a ratio the following type: 1:100000. In this case, we can calculate that a centimeter on the map corresponds to 1000 meters on the ground, since 100000/100 (centimeters in a meter) = 1000 m.

Multiply the distance measured with a ruler or curvimeter, expressed in centimeters, by the number of meters indicated on the map or calculated in one centimeter. The result will be the actual distance, expressed, respectively, in kilometers.

Any map is a miniature image of some territory. A coefficient showing how much the image is reduced in relation to real object, is called scale. Knowing it, you can determine distance By . For real existing maps on paper based scale is a fixed value. For virtual electronic cards this value changes as the magnification of the map image on the monitor screen changes.

Instructions

If yours is based, then find it, which is called a legend. Most often, it is framed. The legend must indicate the scale of the map, which will tell you, measured in distance according to this will be in reality, at . So, if the scale is 1:15000, then this means that 1 cm per map equal to 150 meters on the ground. If the map scale is 1:200000, then 1 cm laid out on it is equal to 2 km in reality

That distance, which interests you. Please note that if you want to determine how quickly you will walk or get from one house to another in or from one settlement to another, then your route will consist of straight segments. You will not move in a straight line, but along a route that runs along streets and roads.

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Lesson questions:

1. Map scales. Measurement by map of straight and curved lines. Accuracy of measuring distances on the map. Distance corrections for slope and tortuosity of lines. The simplest ways to measure areas on a map.

• Map scales.

Map scale shows how many times the length of a line on a map is less than its corresponding length on the ground. It is expressed as a ratio of two numbers. For example, a scale of 1:50,000 means that all terrain lines are depicted on the map with a reduction of 50,000 times, i.e. 1 cm on the map corresponds to 50,000 cm (or 500 m) on the terrain.

Rice. 1. Design of numerical and linear scales on topographic maps and city plans

The scale is indicated under the bottom side of the map frame in digital terms (numerical scale) and in the form of a straight line (linear scale), on the segments of which the corresponding distances on the ground are labeled (Fig. 1). The scale value is also indicated here - the distance in meters (or kilometers) on the ground, corresponding to one centimeter on the map. It is useful to remember the rule: if you cross out the last two zeros on the right side of the ratio, the remaining number will show how many meters on the ground correspond to 1 cm on the map, i.e. the scale value. When comparing several scales, the larger one will be the one with the smaller number on the right side of the ratio. Let’s assume that there are maps at scales of 1:25000, 1:50000 and 1:100000 for the same area. Of these, a scale of 1:25,000 will be the largest, and a scale of 1:100,000 will be the smallest.

The larger the scale of the map, the more detailed the terrain is depicted on it. As the scale of the map decreases, the number of terrain details shown on it also decreases.
The detail of the terrain depicted on topographic maps depends on its nature: the fewer details the terrain contains, the more fully they are displayed on maps of smaller scales.
In our country and many other countries, the main scales for topographic maps are: 1:10000, 1:25000, 1:50000, 1:100000, 1:200000, 1:500000 and 1:1000000.
The maps used by the troops are divided into large-scale, medium-scale and small-scale.

• Measurement by map of straight and curved lines.

To determine on a map the distance between terrain points (objects, objects), using a numerical scale, you need to measure on the map the distance between these points in centimeters and multiply the resulting number by the scale value.
Example, on a map of scale 1:25000 we measure the distance between the bridge and the windmill with a ruler (Fig. 2); it is equal to 7.3 cm, multiply 250 m by 7.3 and get the required distance; it is equal to 1825 meters (250x7.3=1825).

A small distance between two points in a straight line is easier to determine using a linear scale (Fig. 3). To do this, it is enough to apply a measuring compass, the opening of which is equal to the distance between given points on the map, to a linear scale and take a reading in meters or kilometers. In Fig. 3 the measured distance is 1070 m.

Large distances between points along straight lines are usually measured using a long ruler or measuring compass.
In the first case, a numerical scale is used to determine the distance on the map using a ruler (see Fig. 2).
In the second case, the “step” solution of the measuring compass is set so that it corresponds to an integer number of kilometers, and an integer number of “steps” is plotted on the segment measured on the map. The distance that does not fit into the whole number of “steps” of the measuring compass is determined using a linear scale and added to the resulting number of kilometers.
In the same way, distances are measured along winding lines (Fig. 4). In this case, the “step” of the measuring compass should be taken 0.5 or 1 cm, depending on the length and degree of tortuosity of the line being measured.

To determine the length of a route on a map, a special device is used, called a curvimeter (Fig. 5), which is especially convenient for measuring winding and long lines.
The device has a wheel, which is connected by a gear system to an arrow.
When measuring distance with a curvimeter, you need to set its needle to division 99. Holding the curvimeter in a vertical position, move it along the line being measured, without lifting it from the map along the route so that the scale readings increase. Having reached the end point, count the measured distance and multiply it by the denominator of the numerical scale. (In this example, 34x25000=850000, or 8500 m)

• Accuracy of measuring distances on the map. Distance corrections for slope and tortuosity of lines.

Accuracy of determining distances on the map depends on the scale of the map, the nature of the measured lines (straight, winding), the chosen measurement method, the terrain and other factors.
The most accurate way to determine the distance on the map is in a straight line.
When measuring distances using a measuring compass or a ruler with millimeter divisions, the average measurement error in flat areas usually does not exceed 0.7-1 mm on the map scale, which is 17.5-25 m for a map at a scale of 1:25000, scale 1:50000 – 35-50 m, scale 1:100000 – 70-100 m.
In mountainous areas with steep slopes, errors will be greater. This is explained by the fact that when surveying a terrain, it is not the length of the lines on the Earth’s surface that is plotted on the map, but the length of the projections of these lines onto the plane.
For example, With a slope steepness of 20° (Fig. 6) and a distance on the ground of 2120 m, its projection onto the plane (distance on the map) is 2000 m, i.e. 120 m less.
It is calculated that with an inclination angle (steepness of the slope) of 20°, the resulting distance measurement result on the map should be increased by 6% (add 6 m per 100 m), with an inclination angle of 30° - by 15%, and with an angle of 40° - by 23 %.

• The simplest ways to measure areas on a map.

An approximate estimate of the size of the areas is made by eye using the squares of the kilometer grid available on the map. Each grid square of maps of scales 1:10000 - 1:50000 on the ground corresponds to 1 km2, a grid square of maps of scale 1 : 100000 - 4 km2, the square of the map grid at a scale of 1:200000 - 16 km2.
Areas are measured more accurately palette, which is a sheet of transparent plastic with a grid of squares with a side of 10 mm applied to it (depending on the scale of the map and the required measurement accuracy).
Having applied such a palette to the measured object on the map, they first count from it the number of squares that completely fit inside the contour of the object, and then the number of squares intersected by the contour of the object. We take each of the incomplete squares as half a square. As a result of multiplying the area of ​​one square by the sum of squares, the area of ​​the object is obtained.
Using squares of scales 1:25000 and 1:50000, it is convenient to measure the area of ​​small areas with an officer’s ruler, which has special rectangular cutouts. The areas of these rectangles (in hectares) are indicated on the ruler for each gharta scale.

2. Azimuths and directional angle. Magnetic declination, convergence of meridians and direction correction.

True azimuth(Au) - horizontal angle, measured clockwise from 0° to 360° between the northern direction of the true meridian of a given point and the direction to the object (see Fig. 7).
Magnetic azimuth(Am) - horizontal angle, measured clockwise from 0e to 360° between the northern direction of the magnetic meridian of a given point and the direction to the object.
Directional angle(α; DU) - horizontal angle, measured clockwise from 0° to 360° between the northern direction of the vertical grid line of a given point and the direction to the object.
Magnetic declination(δ; Sk) - the angle between the northern direction of the true and magnetic meridians at a given point.
If the magnetic needle deviates from the true meridian to the east, then the declination is eastern (counted with a + sign); if the magnetic needle deviates to the west, then the declination is western (counted with a - sign).

3. Measuring and plotting directional angles on the map. Transition from directional angle to magnetic azimuth and back.

On the ground using a compass (compass) to measure magnetic azimuths directions, from which they then move to directional angles.
On the map on the contrary, they measure directional angles and from them they move on to magnetic azimuths of directions on the ground.

Rice. 8. Changing directional angles on the map with a protractor

Directional angles on the map are measured with a protractor or chord angle meter. Measuring directional angles with a protractor is carried out in the following sequence: the landmark at which the directional angle is measured is connected by a straight line to the standing point so that this straight line is greater than the radius of the protractor and intersects at least one vertical line of the coordinate grid; align the center of the protractor with the intersection point, as shown in Fig. 8 and count the value of the directional angle using the protractor. In our example, the directional angle from point A to point B is 274° (Fig. 8, a), and from point A to point C is 65° (Fig. 8, b).

In practice, there is often a need to determine the magnetic AM from a known directional angle ά, or, conversely, the angle ά from a known magnetic azimuth.

Transition from directional angle to magnetic azimuth and back
The transition from the directional angle to the magnetic azimuth and back is carried out when on the ground it is necessary to use a compass (compass) to find the direction whose directional angle is measured on the map, or vice versa, when it is necessary to put on the map the direction whose magnetic azimuth is measured on the ground with using a compass.
To solve this problem, it is necessary to know the deviation of the magnetic meridian of a given point from the vertical kilometer line. This value is called the direction correction (DC).

If, for example, ά = 97°12", then Am = 97°12" - (2°10"+10°15") = 84°47 " .

4. Preparation according to the data map for movement in azimuths.

Movement in azimuths- This is the main way to navigate in areas poor in landmarks, especially at night and with limited visibility.
Its essence lies in maintaining on the ground the directions specified by magnetic azimuths and the distances determined on the map between the turning points of the intended route. Directions of movement are determined using a compass, distances are measured in steps or using a speedometer.
The initial data for movement along azimuths (magnetic azimuths and distances) are determined from the map, and the time of movement is determined according to the standard and drawn up in the form of a diagram (Fig. 11) or entered into a table (Table 1). Data in this form is given to commanders who do not have topographic maps. If the commander has his own working map, then he draws up the initial data for moving along azimuths directly on the working map.
The route of movement along azimuths is chosen taking into account the terrain's passability, its protective and camouflage properties, so that in a combat situation it provides a quick and covert exit to the specified point.

Table 1

5. Compliance with standards.

Notes

Military topography

Military ecology

Military medical training

Engineering training

Fire training

Many Google Maps users wonder how to measure distance on Google maps. In theory, such an opportunity should exist, but not everyone can find it. Moreover, on the Internet you can find opinions that it is not in Google maps at all.

In fact, this is not true and there is such a possibility. Moreover, everything in this service is done very conveniently. You just need to know where to find it and how to use Google Maps to measure the distance. Let's look at the whole process step by step.

On the computer

After this, to measure the distance between two points, you need to do the following:

• In the left top corner There is a field where you can enter an address to search for it on the map. Next to this field there is a magnifying glass icon - this is the button to start the search, and after them there is an angular arrow icon to the right (“How to get there”). Click on this icon.

• Now you need to enter the starting and ending points of the route. There is a special field for this (in Figure No. 2 it is highlighted lilac color). There you can manually enter the address.

You can also select one of the options that are located a little lower - “My location”, the address of home, work, or other addresses that the user has searched for before.

You can also put a mark directly on the map. To do this, you need to click on the starting point icon with the left mouse button once (in Figure No. 2 it is highlighted in red - it represents a circle), and then in the same way, with the left mouse button, click on the desired location on the map.

For example, let’s select the “My location” option.

• To select the end point, you need to do exactly the same actions as in the second item of this list, but with the second field (in Figure No. 3 highlighted in lilac). For example, let’s put some point on the map manually (click on the point icon on the map - highlighted in red and click on some place on the map). As a result, we get the route shown in Figure 3.

• After this, a little below the panel with the start and end points the distance will be shown (in Figure No. 3 it is highlighted green). It also shows the time it will take to travel along this route. Initially, this time is shown on the condition that you will be traveling by car. This can be changed using the corresponding icons on the panel at the top (highlighted in black). There you can choose options such as cycling, bus, hiking or traveling by plane.

This route can be slightly modified. For example, you can add another point. To do this, click on the plus icon and add another point in exactly the same way.

These points can then be swapped. To do this, simply click on them with the left mouse button and drag the cursor up or down.

Another interesting nuance is that, as you can see in the pictures above, there are points on the route white. They can be moved as the user wants, thereby constantly changing the route.

The distance will always be shown in the same place.

On a smartphone and tablet

Any smartphone or tablet has exactly the same panels. All operations are performed in the same way as shown above, only these panels are arranged in a slightly different order. It won't be difficult to figure it out.

The same operation can be performed using Google Earth. More details in the video below.