The notion of a map

The peculiarities of a cartographic image of the surface

A map is a reduced generalized image of the surface on plane, which is made according to the definite mathematical law and which shows a placing, combinations and connections of natural and social phenomena.

The content of the map is an aggregate of the elements and objects of a region showed on the map and information about them. From other ways of transferring the information (a photograph, a picture, a text etc.) a map differs by a mathematical law of construction, which appears in the use of a definite scale, cartographic projection and includes the transition from physical to mathematical surface. A map also differs by selection and generalization of a displayed content which is determined by a purpose of a map, its scale and peculiarities of a mapped region; by an image of all subjects and phenomenon with the help of notation conventions. Considerable peculiarities of maps are visual perception, measurability and high self-descriptiveness.

Visual perception is a possibility to perceive a space form, a size and a placing of an imaged object. While creating a map most important and substantial things in the content are brought to the forefront in order to identify them easily. In that way a map creates a visual model of a mapped surface.

Measurability is a very important characteristic of the map, which is closely connected with mathematical basis. Measurability gives a possibility to spot to accuracy coordinates, size and placing of objects of the locality, to use maps while working up and carrying out various national and defence arrangements and while solving scientific and technical problems. The measurability of the map is defined by the degree of correspondence of the location of the plotted points on the map and its location on the mapped surface.

Self-descriptiveness of the map is an ability of the map to contain information about imaged objects and phenomenon. None of the textual or graphical material can provide getting information about location and peculiarities of the mapped objects and phenomenon with the speed like map does.

Types of topographic maps

All topographic maps depicted Earth surface, including seas and oceans, are called geographical maps. By content maps can be divided into general geographical and subject maps. General geographical are maps which depict aggregate of basic objects of the locality without singling out any of them. The detail of the imaged relief, hydrography, growth, built-up area, road network and others topographic elements of the locality on the general geographic maps depends on the scale.

General geographical maps are topographic maps which present detailed maps of the locality and which give an opportunity to define both planned and altitude location of the points on the surface. Topographic maps on a scale of 1:1 000 000 and larger are published in the USSR. They are a basis for the maps of a smaller scale.

Subject maps are maps the main content of which is determined by the reflected concrete theme. On maps like that several elements of the location are reflected more detailed or some special information is presented, which is not showed on general geographic maps. The example of the subject maps may serve a geographical review, geological map and other types of the maps. Subject maps also include special maps. Special maps are used for solving concrete problems and are used by definite consumers. Their content has more narrow orientation. Special military maps include road-, air-map and etc. Topo maps which contain information about the surface of the ocean, sea floor are called sea navigation chart.

Scales of topographic maps

By scale topographic maps are divided into:

• small-scale map (1:1 000 000 – 1:500 000);
• middle-scale map (1:200 000 – 1:100 000);
• large-scale map (1:50 000 and larger).

Military maps with scale 1:25 000 – 1:100 000 are used by commanders and headquarters while combating or ruling over army in a battle. They are widely used as working maps in a tactical nexus of ruling over the army. With the help of these maps it’s possible to study the locality while preparation or during operations, to define coordinates of fighting positions of rocket forces and artillery and also the coordinates of aims, take a measurement and clear while designing and building military engineering buildings.

Military maps with scale 1:25 000 are used in the army for detailed research of some important boundaries and areas while forced crossing, landing and etc.

Military maps with scale 1:50 000 are mainly used while defensing, and while attacking predominantly when breaking the enemy through, forced crossing, landing air and sea operation and also while fighting for built-up area.

Maps with scale 1:10 000 or 1:25 000 can be published in addition to other maps for commanders and headquarters while acting in big built-up areas. These maps are for exploring cities and approaches to them, for orientation in the city, target designation and ruling over the army while fighting for built-up area. With this aim there are names of streets, numbers of areas, and the most important buildings with its quantitative and qualitative characteristics on the map of the city.

The basic map is considered to be the map with scale 1:100 000.

Military Maps with scale 1:200 000 and 1:500 000 are used for researching and assessing of the locality while planning and preparing fighting, for ruling over the army in the fighting and planning movements of the army. Besides the map with scale 1:500 000 is used by front aviation as an aerial map.

A topo map with scale 1:200 000 is especially convenient as a highway map, because it reflects rode network visually and fully enough for orientation at the locality and characterizes its appropriateness for motor transport and military equipment. With the help of this map one can study and measure road network and the nature of relief, water line, forest tract and large built-up areas. Enquiries of locality on the back side of the map help to get this addition information. The enquiries contain necessary additional information in generalized and classified form about characteristics of the locality and information about several most important objects, which can be not imaged on the map.

A military map with scale 1:1 000 000 is used by headquarters for studying physiographic conditions of vast areas and for common approximate account for providing operations the army while planning fighting.