Conventional topographic signs and symbols

Objects located on the ground are transferred to the map in the form of special conventional signs.

Topographic signs are conventional symbols that designate various objects on the territory in the form of images in topographic plans and maps. There are a huge number of them, and each is usually assigned to a specific group.

Topographic signs and their designations

All conditional characters can be divided into three categories:

1. Explanatory.

These are all those characters that were not assigned to any other group. They express additional characteristics of objects on the ground. That is, they themselves cannot exist, but only provide more detailed information about objects of extra-scale and contour types.

For example: a forest is depicted on a map, and a leafy tree is added inside the outline, which will indicate the type of plants and their age.

Also to this type of topographic signs are other signs:

• numbers (used to indicate the exact number of something - the low-water level of water areas, the highest elevation points, etc.);
• signatures (used to indicate the proper names of objects - settlements, rivers, etc., to specify the type of enterprise - a concrete or brick factory, explanations of the type of buildings that do not have their own designations, but are distinguished by their functions - hospital, railway booth, etc. ; quantitative characteristics of the object - depth, height, etc.).

2. Contour (large-scale).

These are the topographic signs that can be expressed on the scale of the plan or map.

Such symbols are used to mark forests, swamps and vegetable gardens, lakes, i.e., for such objects that are expressed in the scale of a topographic map. The contours of these topographic signs usually reflect the boundaries of real objects and are expressed in some color (green, blue, white).

Inside the contour is filled with a certain conditional sign.

3. Unscale.

Such symbols include pictures of small objects that are difficult to identify in real terms (for example, a church, a tower, etc.). Their number and parameters directly depend on the size of the plan or map. That is, in plans with a small scale, they will be smaller and in much smaller quantities.

It is also worth noting that elements such as pillars, trees and wells draw on plans of any size. And some signs change their appearance based on the scale of the map.

Out-of-scale conditional topographic signs compares favorably with the contours in that they always accurately show where the objects indicated by them are located.

Do not forget that symbols of this type cannot show the real parameters of the object, so do not measure the size of such signs on the map. Such signs include:

• weather station;
• spring;
• fuel mine.

4. Linear.

These are characters that are displayed in real size only in length (and not in width). Topographic signs and their designations in the pictures can show railways, oil pipelines, routes, etc. They are marked with lines showing the actual length of the object (within a given scale). Such conventional signs are very convenient for orientation.

There are also mixed conventional signs for topographic plans and maps. In particular, characters with a signature. Some objects are marked in this way, including rivers marked with the speed of the current.

Topographic symbols

Symbols of topographic maps:

1. Relief:

• horizontal
• bergshtrikhi (direction indicators of slopes);
• contour line captions.

2. Cities and villages, industrial centers, roads and communication lines:

• power plants;
• careers;
• chimneys and factories with pipes;
• forest and field roads;
• villages, villages, cities.

3. Hydrography:

• well;
• rivers and streams;
• lakes;
• metal and wooden bridges;
• marinas;
• dams;
• swamps.

4. Vegetation:

• meadows;
• arable land;
• cutting down;
• Shrubs
• orchards.

5. An isoline is a line that combines points with equivalent data of the drawn lines:

• isobars (equal atmospheric pressure);
• isotherms (equal air temperature);
• isohypses (also called horizontal) - equal heights of the earth's surface.

Such topographic signs are used at any ratio, including 1: 1,500, 5,000.

Scale

Scale is the ratio of the length of an object on a map or plan to its real length. So, this is data on how many times the unit is less than the real interval. For example, you need to measure 1 cm on a topographic plan with conventional signs and with a scale of 1: 1,500. This suggests that the interval, which is 1 cm on the map, will be 1,500 cm (15 m) in real terrain.

Scale happens:

1. Graphic.

A) linear.

It happens that the ratio is not equal to 1 cm. Then use a linear scale. This is an auxiliary tool, a ruler that is applied to simplify distance measurements. Most often, this scale is used on topographic plans. Then you definitely need to use a caliper. To do this, the two ends of the tool must be put on the division of the linear scale and move it according to plan.

B) transverse.

A nomogram (an image of functions of several variables that allows you to explore the dependence functions without calculations, only thanks to simple geometric operations), which is created by observing the proportionality of segments of parallel lines. They cross the sides of the corner.

To do this, the length is measured on the line below this type of scale, while the right side should be on the whole division of OM, and the left side should go beyond 0.

2. Named.

Speech information about which interval in reality is 1 cm on the plan or map. This type of scale is indicated by named numbers and the corresponding length of two segments on the map in kind (for example, 1 cm - 3 km).

The verbal form is convenient, since the length of the lines on the terrain is usually found in meters, and on the maps and plans - in centimeters. 1 cm is 30 meters, which means that the numerical scale will be 1: 3000.

1 m is 100 cm, that is, the number of meters of terrain contained in 1 cm of the plan or map will be easy to find by dividing the denominator of the numerical scale by 100.

3. Numerical.

Scales of this type are used most often. They are also called two-kilometer, five-kilometer, etc. They are depicted as fractions. The numerator in it is one, and the denominator is a number that indicates the number of times the image is reduced (1: M).

If you want to compare different numerical scales, then the smallest will be the one with the greater denominator M. The greatest will be the ratio with the lowest denominator M.

For example: a scale of 1:10,000 is larger than a scale of 1: 100,000. A scale of 1:50,000 is smaller than a scale of 1:10,000. In Russia, there are standard numerical scales: from 1: 10,000 to 1: 1,000,000.

One and the same scale can be written in any of the above ways, while the essence remains the same. Using the ratio, you can measure the interval between any objects (volcanoes, settlements, lakes, rivers, etc.). You just need to take a ruler and measure the distance. The resulting number of centimeters must be multiplied by the denominator of the fraction.

What scale are most common?

And now it’s worth considering the scales most common for use in Russia.

1. 1: 5000. In the inscription on the plan or map with topographic signs 5000 all numbers are expressed in cm. Such an inscription means that 1 cm on the map contains 5000 cm on the ground. For convenience, it is worth translating centimeters to meters. It turns out that 1 cm is equal to 50 meters (or 5 km).
2. 1: 500. Topographic signs with a scale of 1: 500 are made specifically for Moscow and its forest park zone. The application of this scale was required due to the density of buildings in the city and a large number of underground utilities.
3. 1: 2000.
4. 1: 1500. Often used scale. Convenient for compilation and reading.

And now it should be noted the most common conditional topographic signs (1,500, etc.).

1. Surveying points:

• points of planned point networks of long and short-term fixing on the ground, as well as in the walls and corners of capital buildings;
• boundary signs and posts of the project planning;
• places of the state geodetic network (mounds, buildings, natural hillocks, outlier rocks);
• astronomical and landmark points;
• the location of the center grid during construction;
• leveling marks: fundamental and soil benchmarks, rock and wall marks.

2. Buildings and their parts, structures:

• fire-resistant residential and non-residential premises of brick, stone and cinder block;
• non-flame retardant residential and non-residential buildings (wooden and adobe);
• residential and non-residential buildings of a mixed type with a fire-resistant lower floor of wood with thin brick lining;
• construction and destruction of structures;
• religious buildings.

3. Agricultural, industrial and communal production:

• with pipes and without;
• mouths of active and inactive adits, trunks, pits;
• rocks and dumps;
• fortified and unsecured slopes characteristic of conventional signs of topographic plans of 1,500 scale;
• wells, wells, oil outlets, gas stations and tanks;
• technological, marine and loading racks;
• cranes, supports, searchlights and transformers.

4. Railways and nearby structures:

• monorail, electrified, narrow gauge railways;
• Tram lines under construction and operation;
• entrances to galleries and tunnels;
• conversion arrows and turntables;
• station tracks;
• crossings, barriers, gates and viaducts;
• cargo platforms and loading and unloading platforms;
• semaphores and traffic lights;
• warning discs, signs and shields;
• motorways and carriageways;
• pack and hiking trails, cattle passes.

Other scales

In the main land management practice, maps and plans are usually created on a scale of 1:10,000 to 1:50,000. Symbols for topographic plans of such scales are most often the same in image, but differ only in size.

Accuracy

This is the name for a segment of a horizontally laid line.

The marginal probability with which you can measure and build segments is limited to 0.01 cm. The number of meters of terrain corresponding to it on the scale of the plan or map depicts the ultimate graphic accuracy of a particular ratio. This accuracy indicates the length of the laid horizontal line of the terrain (in meters). So, to determine this accuracy, you need to divide the denominator of the numerical scale by 10,000.

For example: a scale of 1:25 000 is 2.5 m; 1: 100 000 equals 10 m.

Mapping

It is used to show any geographical objects on the map. There are several basic options:

1. The method of habitats ("space", "area"). Areas where natural or social phenomena are common (objects of the animal world and plants).
2. Traffic signs. This mapping method is used to show the direction of movement of the sea, winds, traffic flows.
3. Quality background. Determines the separability of sites on any grounds: economic, political or natural. Explains the qualitative characteristics of continuous phenomena on the earth's surface (soil) or objects having a massive dispersed space (population).
4. Quantitative background.

Indicates subdivisions of sites for any quantitative indicator.

Principle of equal intervals

It will help to determine the average value of the phenomenon. There are several ways to get the intervals you need.

1. Cartogram. To get the interval, you need to divide the difference between the largest and smallest numbers by 5. For example: 100 - 25 = 75. The resulting number 75 must be divided by 5, it turns out 15. Therefore, the resulting intervals will vary from 25 to 100 every 15 units: 25 - 40 etc.
2. Cartodiagram. This method is used in cases where it is necessary to show the total magnitude of the phenomenon in a certain territory (number of students, fresh water supply, etc.).
3. Map scheme. This method is a simplified view of a map that does not have a degree network.

Topographic maps

This is an image that is created in a reduced form, taking into account certain mathematical laws. It can be built on the plane of the entire planet or of individual components in accordance with the curvature of the Earth.

According to the meridians, a topographic map with conventional signs for topographic plans 1,500 is oriented so that the north is always on top. This greatly facilitates terrain orientation when using a compass or other device.

Any topographic map has many characteristics. The main ones are scale and informational content. Most often, the rule is observed that the larger the scale, the higher the information content.

Informativeness - the quantity and quality of information that the map contains.

Card quality is expressed:

• relevance (the more modern the map, the more accurate its data);
• accuracy of lines, contours of forests, etc.

The amount of information is also very important. More detailed information makes it easier to work with the map (for example, the presence of wells, fences, etc.).

Informativeness of topographic maps is provided by conventional signs.

By scale, the cards are divided into:

1. Large-scale (ratio 1: 100,000 or larger).
2. Medium-scale (from 1: 200 000 to 1: 1 000 000).
3. Small-scale (ratio less than 1: 1,000,000).

When creating any topographic maps with conventional signs, it is better to additionally build:

• cartographic grid (meridians and parallels);
• kilometer grid (lines that are parallel to the axial meridian and equator).

In addition, it must be remembered that the scale of the map at each individual point will have its own individual value. It will depend on what is the longitude and latitude of a particular point.

Plan

This is a projection, a small image of something on a horizontal plane.

Plans are:

1. Topographic. This is a drawing of the area, which shows only the situation.
2. Contour (situational). On such topographic plans with conventional signs, in addition to the situation, the relief is also depicted. Unlike the map, the scale of the plan is the same at all points.

Inaccuracies

Shortcomings associated with measuring distance on maps can be related to:

• With inaccuracy of measurements.
• With the errors that were made when compiling the map itself.
• With bruises, bends, kinks and other defects on the topographic plan or map.

Amendments

Even if all the above conditions are met, there is a risk that the measurements will not be accurate. This can happen for several reasons:

1. Incline. Also, when establishing the distance of any objects, it is necessary to take into account the slope, since the map is only a projection of the real terrain on a plane. Accordingly, it does not take into account these inclinations and may give an incorrect result. Moving on an incline, a person additionally goes up and down. That is, the actual distance on the plane will always be greater than the gap that was measured on the map. For example, with a slope of 42 degrees, the correction factor will be 1.35. This means that the distance set on the map or plan must be multiplied by 1.35.
2. Straightening roads. On small-scale topographic maps with conventional signs, as well as on mountain charts, it is often not possible to draw in detail all the bends of the roads. Therefore, they are usually straightened, because of which the previously calculated distance on the map will be less than the actual, up to a difference of 1.3 times.