Map language
Methods of cartographic representation – systems of symbols used to convey objects and phenomena that differ in the nature of spatial localization and location.
The use of conventional signs is the main feature that distinguishes the map from many other graphic models such, (aerial and space images, panoramas, landscapes).
Symbols on a map are visually perceived elements of the image, conventionally representing processes and phenomena of the surrounding world, their location, qualitative and quantitative characteristics, structure, dynamics, etc.
The map language is developed by the cartography section of semiotics.
The language of a map is a system of signs used in cartography, which includes conventional designations, methods of representation, rules of their creation, use and reading when creating and using maps.
Two layers (sub-languages) can be distinguished in the language of a map:
- reflects location of the objects being mapped, their spatial shape, orientation, mutual position
- the content essence of these phenomena, their internal structure, qualitative and quantitative characteristics.
The main functions of a map language are communicative, i.e. transfer of a certain amount of information from a map creator to a reader, and cognitive – obtaining new knowledge about the mapped object.
Symbols
Symbols are graphic symbols used to show (designate) on the map the type of objects, their location, shape, size, qualitative and quantitative characteristics.
The use of conventional signs allows:
- show real and abstract objects (e.g., the height of snow cover, index of continental climate);
- depict objects that are not visible to man (gravitational and magnetic fields, etc.);
- convey internal characteristics and structure of objects (volume and structure of industrial production, population composition, etc.);
- reflect mutual relations of objects: order and hierarchy, proportionality, difference, co-subordination (for example, geological stratigraphy);
- show the dynamics of phenomena and processes (flow changes in river basins by months);
- to greatly reduce the image (on a small-scale map, instead of showing individual houses and neighborhoods, an entire settlement can be circled).
Symbols used on maps are divided into three main groups:
- Out-of-scale, or point-based, which are used to show objects that are localized at points, such as oil fields or cities on small-scale maps. The out-of-scale nature of the signs manifests itself in the fact that their dimensions (when expressed at map scale) are always much larger than the true dimensions of the objects on the ground;
- Linear, used to represent linear objects: rivers, roads, borders, tectonic faults, etc. They are scaleable in length, but out of scale in width;
- Area-based, used for objects that retain their dimensions and outlines on the map, such as forests, lakes, soil habitats, etc. Such signs usually consist of an outline and its filling, are not always scaled and allow to accurately determine the area of objects.
Icons
The method of icons is used to show objects localized in points and usually not expressed in the scale of the map (Fig.). These can be settlements, mineral deposits, industrial enterprises, separate constructions, landmarks, etc. Icons allow to characterize qualitative and quantitative features of objects and their internal structure.
There are three types of icons:
- abstract geometric icons – circles, squares, stars, rhombuses, etc.; the size of the sign reflects quantitative characteristics, the color or shading – qualitative features, and the structure of the sign conveys the structure of the object itself;
- alphabetic icons – indicating deposits of phosphorites or aluminum;
- visual icons (pictograms) – they resemble the depicted object, for example, the drawing of an airplane indicates an airfield, a tourist tent – campsites, etc;
Linear signs
This method is used to represent real or abstract objects localized on lines. These include, for example, coastlines, faults, roads, atmospheric fronts, administrative boundaries. Different drawing and color of line signs convey qualitative and quantitative characteristics of objects: type of coastline, depth of faults, number of railroad tracks, warm and cold fronts, etc.
Linear sign is out of scale in width, but its axis should coincide with the position of the real object on the terrain. If the transition is gradual or the boundary is not clear, the linear sign may be conveyed by a strip.
Isolines
Isolines are lines of equal values of the mapped object. Isolines are used to depict continuous, smoothly changing phenomena that form physical fields (relief, pressure, temperature). They are depicted by horizontals (isohypses, isobars, isotherms).
The distance between contour lines on the map is called contour plotting.