The science of reading cards and signs began to emerge simultaneously with the emergence of the most primitive writing. Topographic maps to this day can help solve a wide range of scientific and practical problems. The use of maps as specific models for displaying the surrounding reality in order to study the phenomena depicted on it is called the cartographic method of research. Nowadays, there are several ways to read topographic maps depending on the goals pursued. Now topographic maps are widely used both for research and military purposes, since this method of displaying information about the surrounding reality has proved to be a high-quality, effective and universal source.
Topographic map concept
A topographic map is an accurate and detailed plan of a small area with a view to its further in-depth study and identification of patterns and relationships. A topographic map is also called a graphic document about a certain territory, which contains visual images of the landscape and nearby objects, such as roads, cultural objects, types of vegetation and soil, communications, and much more.
The branch of science that studies topographic maps is called topography.
Of great importance in such a map is the scale, since it is a parameter of accuracy and the details of displaying on the map a variety of objects existing in the selected area. The scale also indirectly determines the purpose of the map: different map details are suitable for different tasks of its application. For example, without reading topographic maps, military topography would have become almost impossible.
Scale classification
Topographic maps are usually distinguished by scale. Different maps are created for a variety of purposes, so the rules for reading topographic maps may vary slightly. The scale condition in military topography is especially relevant:
- Maps with a scale of about 1:10,000 - 1:25,000 are considered by cartographers and researchers to be the most detailed and the most detailed. Such maps are intended for careful consideration and analysis of individual sections of the territory. Often they are used in military topography: the study of topographic maps of a similar scale helps the unit commanders when landing airborne assault forces, as well as when crossing water barriers, conducting combat in cities or during the construction of special structures. In addition, they are often used for measurements of high accuracy when performing work on the engineering equipment of territories or topographic and geodetic training.
- The scale of 1:50 000 is intended for the analysis of territory, target designation or orientation: reading topographic maps in such cases greatly facilitates the task. It is usually used by military units in various types of military operations, and in particular when creating a defense. During the offensive, the map is used to evaluate the surroundings during the breakthrough of the enemy’s defense, as well as to cross military barriers and in battles for towns and cities. It is also convenient to use such cards for topographic and geodetic training of shooting, designing various military and engineering structures, and in the process of summing up the necessary calculations for the engineering equipment of the territory.
- Scale 1: 100,000 is well suited for analyzing territories and assessing its capabilities when planning a battle, as well as organizing troops, orienting yourself on the ground, and surveying geodesy. In addition, reading and analyzing a topographic map is excellent for finding out the coordinates of necessary objects or tasks of an enemy. Among other things, topographic maps are often used in the design process of military engineering buildings and in the performance of various actions to equip territories.
- The study and analysis of topographic maps with a scale of 1: 200,000 helps to cope with the organization of hostilities and the subsequent command and control of troops. This map is also often used as a road map, since the road network and its quality are perfectly displayed on it. In addition to roads, the nature of the landscape is clearly shown on the map, often water and forest objects and important settlements are depicted in detail. That is why maps of this scale are used in the analysis of terrain.
- The scale of the maps 1: 500 000 is often used in the study of the general nature of the relief of the territory when conducting various operations. Topographic maps and the study of their rectangular coordinates contributes to the organization of interaction and command and control, as well as the orientation and drawing of a general military situation.
- The scale of 1: 1 000 000 is quite small and inadequate, so it is suitable for an initial assessment of the territory and the subsequent study of its main natural parameters: such maps cover large geographical areas. Intended for military-geographical assessment of military operations and operations, as well as for the organization of troops and to solve many other issues.
The concept of conventional signs
Conventional signs are called special characters that mark the location of an object in a designated area. The designation is intended to convey the quantitative and qualitative characteristics of the object on the map. At present, in the Russian Federation and the CIS countries, 465 conventional signs are used for this purpose. The correct reading of maps and symbols will lead to the most complete and correct understanding of the information contained in the topographic map.
Groups of identical objects on the ground are displayed on maps by means of a basic symbol. Qualitative or quantitative characteristics of the objects of this group are indicated by complicating the main symbol.
The larger the scale of the map, the greater the number of objects with more accurate details can be displayed on this segment of the terrain. With a reduction in scale, the information content of the map decreases due to a reduction in free space on the sheet.
On large-scale maps (1:25 000 - 1:10 000), whenever possible, all local objects and their individual features with practical significance are displayed. On images with a smaller scale (1: 200,000 - 1: 500,000), only the most significant characteristics will be displayed, with a rather serious generalization of the outlines and simplification of other indicators.
Classification of conventional signs
Reading topographic maps without symbols would be extremely difficult and almost useless. Signs and conditional lines are an integral part of the topographic plan. There are many conventional signs, they are divided into different groups according to different signs. However, basically, topographic signs for reading a topographic map are divided into the following groups:
- large-scale:
- off-scale;
- explanatory.
To understand the difference between these three categories, it is worth considering each of them in more detail.
Large-scale
Large-scale legend or outline - they mark objects on topographic maps that can be expressed on the scale of this map: their numerical parameters, such as length, area or width, are easily measured on the map. The icons of this group include the outline (the outline of the object) and the explanatory designation inside the outline in the form of a color fill, hatching, or grid of identical small symbols in the pattern (they are called storage marks) that indicate the appearance of the object. Outlines are usually marked with dashed lines if they do not cross other important lines of the terrain (for example, they may coincide with the coastline, road, ditch, etc.).
Out of scale
Small-scale or objects with point symbols indicate small solitary objects, whether it be monuments, single houses, wells, water towers, etc. Objects of this kind are not expressed in scale. The curly symbol of a point symbol has a main point, which marks the exact location of the object on the ground, while simultaneously indicating the genus of the object. The main point is essentially a geometric center - such points must be used when searching for the exact coordinates of objects on the ground or when there is a need to measure the distances between them.
Extra-large signs are divided into 4 groups according to their location relative to the main point:
- signs with a center of symmetry (circle, rectangle, asterisk, square, etc.) - the center point coincides with the center of symmetry;
- signs with a wide base: the main point is in the middle of the base;
- signs with a base in the form of a right angle: the main point will be at the top of the corner;
- signs that combine several characters: the main point will be in the center of symmetry of the lower figure.
Explanatory
Explanatory signs are used for an additional characteristic - qualitative or quantitative - of the depicted objects. Also, an explanatory sign can display a kind of object: for example, a conditional icon of a tree inside the borders of the forest.
Topographic map design
When reading topographic maps and their rectangular coordinates, it is necessary to pay attention not only to the actual image of the map, but also to the external border design. It contains no less important information about the area depicted on the topographic map. Each sheet has a variety of information outside the map, which is necessary for reading the topographic plan of the area map.
Firstly, the nomenclature should include the number and year of publication of the map - this is especially important when working with old maps, since the information on it may turn out to be outdated and even irrelevant in modern realities due to the changing landscape of the terrain or the development of territories.
Secondly, information on magnetic declination, as well as data on the convergence of the meridians and the figure of the direction correction, is given under the lower border of the frame on the left side - this information is especially important in high accuracy calculations. The drawing will show the relationship of these angular values to simplify the perception of this information. In the middle, as a rule, the numerical and linear scales of the topographic map are placed, as well as the magnitude of the scale and the height of the cross-section of the relief. In the lower right corner is a mortgage scale, which is designed to calculate the slope of the ramps. It also indicates when and with what method the map was created.
Thirdly, between the external and internal frames of the map, digitization of horizontal and vertical lines of the coordinate network is given. There are also inscribed the geographical coordinates - latitudes and longitudes - the corners of the frame. Using this visual grid, positioning is much easier and more affordable. In addition, the frame is divided into minute divisions, and those, in turn, are divided into six equal segments for 10 seconds - this system allows you to determine the exact coordinates of the topographic map.
Fourth, on the map at the exits of highways and railways, the name of the nearest city, village or station in the direction of this path is given with the distance to this settlement (it is given in kilometers).
Finally, inside the frames are the proper names of villages, cities, towns, which are only partially printed on the sheet.
Reading topographic maps
The study of the territory according to a topographic map includes determining the nature of the territory and the qualitative and quantitative characteristics of individual objects. Reading a map implies a complete and accurate perception of the symbolism of symbols, as well as the effective recognition of the types of objects depicted by them and their individual features. There are several methods for reading a topographic map, but they all contain similar steps.
Initially, an initial acquaintance with the map occurs. According to the information placed in the out-of-bound space, you can calculate the scale, study the height of the cross-section of the landscape and check the time of creating the map, having learned the relevance of the information provided. Information on the scale and height of the cross-section of the landscape will help to find out the level of detail of the topographic map. Having information about the scale, you can quickly estimate the size of local objects and calculate the distance between them. These actions involve the shortest reading of a topographic map.
Next comes the stage of deeper and more detailed study. The rules for reading topographic maps imply the use of information on the declination of the magnetic needle and subsequent correction for direction. Knowing the correction, you can quickly calculate directional angles, translating them into magnetic azimuths or orient the topographic along the line of a kilometer grid on the ground.
Topographic map of the area
Everyone who fell into the hands of a topographic map at first experienced some embarrassment and confusion: the abundance of non-obvious conventional signs, lines, borders and fills are introduced into thoughtfulness. However, if you understand it properly, it becomes clear that there is nothing complicated in reading the topographic map and map symbols: you just need to take a closer look at all the symbols and pay attention to longitudes and latitudes in order to correctly orient yourself on the terrain. It is important to consider all the symbols for a more complete understanding of the symbolism of the plan.
There are several tricks and methods for reading topographic maps. Primary visual analysis and the study of descriptions on maps are used in the course of a general familiarization with the selected territory, as well as for the development of a plan for further actions in this territory. After an in-depth study of the phenomena depicted on the map, followed by the presentation of the main information points, the final stage follows: the interpretation of the images, the disclosure of their relationships and the establishment of geographical patterns. The general rules for reading topographic maps imply a clear sequence on which the degree of detail in the analysis of the terrain depends. Although the map can be read in different ways, the general analysis procedure is nevertheless preserved.
Among the techniques and methods for reading topographic maps, the following are distinguished:
- Cartometric analysis: includes measurement and calculation of topographic maps of quantitative characteristics. This includes determining coordinates, areas, distances, heights, angles, and other parameters. Such information serves as the basis for calculating certain indicators that will characterize not a single object on the ground, but a picture of the location of similar objects to identify morphometric data. As a result of such an analysis, a detailed description of the relief is obtained: the range of heights, the degree of vertical and horizontal division of the earth, karst, ravine, etc.
- Graphical analysis: involves the study of the area using profiles, block diagrams and other constructions. Using a topographic map, a surface profile of the Earth is plotted on a specific territory. Along the profile line, natural characteristics and socio-economically important objects are noted with the help of conditional icons. Thus, you can find out the relationship of the relief with these indicators. Comparison of various signs on the map often allows preliminary zoning of the selected territory.
The determination of the necessary method for reading topographic maps depends on the purpose of the study and the task. A thorough study of the territory implies an accurate determination of the number of settlements, their type and dispersal, layout, density of development.
When considering a road network map, it is easy to clarify the level of development of roads and their quality. In addition, you can determine the terrain and the possibility of using vehicles to cross the terrain. A detailed analysis clarifies the presence of bridges or embankments and other structures, difficult terrain, steep climbs and much more.
When analyzing hydrography on a map, the presence of water bodies is revealed. Water surfaces are depicted on the plan in contrasting blue, so that they stand out sharply against the background of other conventional signs. , , , , , . , , , , , .
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