Scales of topographic maps and plans. Geographic maps of medium and small scales What is the name of the scale labeled on a small-scale map

We have seen that topographic maps paint a detailed picture of an area, preserving the outlines of many individual features of the area and therefore allowing them to be measured. At the same time, we became convinced that the larger the scale, the greater the number of sheets needed for the same area and the more difficult it is to use them.

Meanwhile, in many cases, the reader of the map is not interested in minor details of the area, but in the main features of the geographical landscape; he is not interested in studying the details, but in a broad general overview of the territory, sometimes quite significant in size. Small-scale maps satisfy these requirements.

In fact, a tourist who wandered in the mountains knows well the value of a topographic map, on which he found not only images of barely noticeable paths in the area, but even individual trees, piles of stones and other details that instilled in him confidence in the correctness of the chosen path. But these details are useless to the motorist. He needs a map of a relatively small scale, covering a significant area, which shows highways, but not paths or even country roads, with the exception of those that may be of approximate value. Another example comes from military cartography. In trench warfare, units occupying combat positions are supplied with large-scale maps (1:25,000 and larger), on which trenches, wire fences, shelters, machine-gun nests, observation posts, etc. are depicted in detail. But for judging the general situation at the front this information is unnecessary. The command uses maps of much smaller scales (1:200,000-1:500,000), on which combat locations and defensive structures are given only in general terms, but the road network is indicated in detail.

As the scale decreases, the content of the map undergoes significant changes. It consists both in simplifying the outlines (generalization) of individual objects, and in their limitation and selection. While a village with an area of ​​1 km 2 on a map of 1: 100,000 scale will occupy 1 cm 2, at 1: 500,000 scale it will be reduced to 4 mm 2, and at 1: 1000,000 - to 1 mm 2. If on a 1:100,000 scale we manage to show all the streets and passages of this village, then on a 1:500,000 map we will be able to preserve only the general configuration of the village, and on a 1:1,000,000 scale we will depict it with a symbol in the form of a punch of one or another design. At the same time, the number of points being plotted is reduced, individual buildings, small villages, etc. are omitted.

Small streams are not shown in the river network; if we assume, of course with certain exceptions, that streams with a length of more than 1 cm should be plotted on the map on a map scale, this means that on a 1:100,000 map all streams over 1 km will be depicted, while on a 1:10,000,000 map of rivers less than 100 km will be missing. A large-scale map depicts the smallest convolutions that exist in reality, while on a small scale it is possible to preserve only the most important directions of flows. The other contents of the map are also subject to this process, which cartographers call generalization or generalization.

As a result of the consistent reduction in scale and the resulting generalization, the possibility of drawing individual objects on the map in their actual outlines is gradually reduced; the latter are increasingly being replaced by symbolic images - non-scale conventional signs.

On topographic maps, that is, maps larger than 1:200,000 scale, the vast majority of objects appear in their configuration; medium-scale maps (1: 200,000 - 1: 1,000,000) still retain this property of topographic maps for a number of objects, but on maps smaller than 1: 1,000,000, out-of-scale signs replace images that convey the actual outlines of objects. Often these features serve as the basis for classifying maps by scale to divide them into large-, medium- and small-scale maps.

The transition to off-scale signs, which, as a rule, exaggerate the space occupied by the corresponding elements of the landscape, entails the impossibility of any accurate measurement of them on small-scale maps. Therefore, on small-scale maps, skillful generalization is especially important, which ensures the maximum cartographic accuracy of the image for a given scale. The meaning of this expression can be explained by drawings in which the city of Mainz on the river is depicted twice, at 1: 500,000 and 1: 15,000,000 scales. Reine. On the first map, where the city retains its actual outlines, it is located on the left bank of the river. The Rhine, being at the same time almost entirely north of the parallel of 50°. When the scale is reduced to 1:15,000,000 and the cartographically correct image of the river, the space between the river and the parallel becomes so small that it is graphically impossible to fit into it the punch assigned to the category of cities to which Mainz belongs. If you show the punchline north of the 50° parallel, it will partially cross over to the right bank of the river and create the impression that the city is spread out on both banks, which is contrary to geographical reality. In such cases, the punch is shifted, placing most of it south of the 50° parallel. For another example, we take the city of The Hague, located 2 km from the North Sea coast (the city center is 4.5 km away). The drawings reproduce the image of The Hague at 1: 1,000,000 and 1: 15,000,000 scales; in the first case, the accuracy of the configuration of the city and its position relative to the coastline was completely preserved, while on the 1:15,000,000 map, where the size of the punch was taken equal to 1 mm, it turned out that the latter touched the coastline and created the impression that The Hague lies directly on the sea coast.

The transition to small-scale maps, accompanied by a skillful generalization of the material and the exclusion of minor details, often leads to a remarkable effect - the main elements of the landscape, previously obscured by minor details, now come to the fore. The map takes on a generalizing character; it becomes an indispensable tool for studying and solving broad general geographic, economic and political issues related to the distribution of phenomena on the earth's surface.

TYPES OF CARDS

Maps are divided into groups according to a number of characteristics: scale, subject matter, territorial coverage, projection, etc. However, any correctly carried out classification must take into account at least the first two signs. In the United States, there are three groups of scale: large-scale maps (including topographic), medium-scale and small-scale, or overview.

Large scale maps are basic because they provide primary information used in compiling maps of medium and small scales. The most common of these are topographic maps at a scale larger than 1:250,000.

On modern topographic maps, relief is usually shown using isohypses, or contour lines, that connect points that have the same height above ground level (usually sea level). The combination of such lines gives a very expressive picture of the relief of the earth's surface and makes it possible to determine the following characteristics: angle of inclination, slope profile and relative elevations. In addition to depicting the relief, topographic maps contain other useful information. They usually show transport routes, populated areas, political and administrative borders. The set of additional information (for example, the distribution of forests, swamps, loose sandy massifs, etc.) depends on the purpose of the maps and the characteristic features of the area.

No country needing to assess its natural resources can do without topographic surveying, which is greatly facilitated by the use of aerial photographs. Nevertheless, there are still no topographic maps for many areas of the globe, so necessary for engineering purposes. Progress in solving this problem has been achieved with the help of the so-called. orthophotomaps. As the basis for orthophoto maps, computer-processed planned aerial photographs with increased brightness of colors and contour lines, boundaries, geographical names, etc. are used on them. Orthophoto maps and satellite images with elements of topographic load raised on them are much less labor-intensive to produce than traditional topographic maps. Many thematic large-scale maps geological, soil, vegetation and land use use topographic maps as a basis on which a special load is applied. Other specialized large-scale maps, such as cadastral maps or city plans, may not have a topographic basis. Usually on such maps the relief is either not shown at all or is depicted very schematically.

Medium-scale maps. Both large-scale topographic maps and medium-scale maps are usually produced in sets, each of which meets specific requirements. Most medium-scale ones are published for regional planning or navigation needs. The medium-scale International World Map and US aeronautical maps have the greatest territorial coverage. Both sets of maps are produced in a scale of 1:1,000,000, the most common for medium-scale maps. When preparing the International World Map, each country issues maps on its territory prepared in accordance with specified general requirements. This work is coordinated by the UN, but many maps are out of date and others are not yet completed. The content of the International World Map basically corresponds to the content of topographic maps, but is more generalized. The same applies to aeronautical maps of the world, but most sheets of these maps have an additional special load applied to them. Aeronautical maps cover the entire landmass. Some nautical or hydrographic maps are also compiled at a medium scale, with special attention paid to the depiction of bodies of water and coastlines. Some administrative and road maps are also at medium scale.

The content of the article

MAP, a reduced generalized image of the Earth's surface (or part of it) on a plane. Man has been creating maps since ancient times, trying to visualize the relative location of various areas of land and seas. A collection of maps, usually bound together, is called an atlas, a term coined by the Flemish Renaissance cartographer Gerardus Mercator.

A ball (sphere) with a cartographic image of the Earth applied to its surface is called a globe. This is the most accurate representation of the earth's surface. All maps that provide an image of a ball on a plane have some kind of distortion that cannot be eliminated. However, maps have certain advantages over the globe. For example, a world map allows you to look at the entire earth's surface (i.e., its image), while on a globe no more than half of the globe is visible from one point; therefore, maps are more convenient when considering the entire surface of the Earth. In addition, it is much easier to measure angles and directions on a map than on a globe. Currently, globes are rarely used for navigation purposes. Depicting territories on a spherical surface that are no larger than the subcontinent does not provide virtually any advantages, which is why in such cases maps are used rather than segments of the globe. Moreover, maps are much easier to make, transport and store (although some of these difficulties can be overcome by using inflatable globes).

KEY FEATURES OF THE CARDS

Despite the amazing variety of existing maps, most of them share some common features. Even contour maps, which are designed to be as lightweight as possible so that students can add additional information of their choice, usually have a grid, scale, and datum features (such as coastlines). In addition, the cards are usually marked with inscriptions and symbols, and a legend is attached to them.

Coordinate grid

is a system of mutually intersecting lines indicating latitude and longitude on a map or the surface of a globe. Lines indicating latitude run in the east-west direction parallel to the equator (whose latitude is 0°); The latitude of the poles is considered equal to 90° (north latitude for the North Pole and south latitude for the South Pole). Since these lines do not intersect and are mutually parallel, they are also called parallels. Of these, only the equator is the largest circle (the plane bounded by this line, passing through the center of the Earth, cuts the globe in half). The remaining parallels are circles, the length of which naturally decreases with distance from the equator. All lines of longitude - meridians - are halves of a large circle, converging at the poles. The meridians run in the north-south direction, from pole to pole; the angular distance is calculated from them from the prime meridian, designated as 0° longitude, to the east and west to 180° (in this case, longitudes that are measured in the eastern direction are designated by the letters “E”, and in the western direction - “W.” d.") . Unlike the equator, which is equidistant from the poles throughout and is in this sense a “natural” reference point when determining latitude, the prime meridian from which longitude is measured is chosen arbitrarily. In accordance with international agreement, the meridian of the Greenwich Astronomical Observatory (now located in London) is taken as the origin of coordinates (0° longitude). However, before this agreement was reached, some cartographers used the Canary or Azores Islands, Paris, Philadelphia, Rome, Tokyo, Pulkovo, etc. as prime meridians.

On the surface of the globe, the lines of parallels and meridians intersect at an angle of 90°; As for maps, this ratio is preserved only in some cases. Both on maps and on globes a certain system of meridians and parallels (drawn at 5°, 10°, 15° or 30°) is usually marked. In addition to this, maps and globes show the Tropic of Cancer (23 1/2 ° N), the Tropic of Capricorn (23 1/2 ° S), and the Arctic Circle ( 66 1/2°N) and the Antarctic Circle (66 1/2°S). Often maps are also marked with the International Date Line, which generally coincides with 180° of longitude.

Scale

cards can be numerical (ratio of numbers or fraction, for example, 1:25,000 or 1/25,000); verbal or linear (graphic). In the example given, a unit of length on the map corresponds to 25,000 such units on the ground. The same ratio can be expressed in the words: “1 cm is equal to 250 m” or, even shorter: “there are 250 m in 1 cm.” In some countries that traditionally use non-metric measures of length (USA, etc.), the scale is expressed in inches, feet and miles, for example, 1:63,360 or “1 inch is 1 mile.” A linear scale is depicted as a line with divisions marked at certain intervals, against which the corresponding distances on the earth's surface are indicated. The graphical representation of scale has certain advantages over the other two ways of expressing it. In particular, if the size of the map changes when it is copied or projected onto the screen, then only the graphical scale, which undergoes changes along with the entire map, remains correct. Sometimes, in addition to the length scale, the area scale is also used. Globes may use any of the scale symbols above.

Basic elements and conventional cartographic signs.

The elements of the geographical basis include the image of the coastline, watercourses, political boundaries, etc., which create the basis against which the spatial distribution of the displayed phenomenon is shown. When compiling maps, many symbols are used, which are divided into several categories: non-scale, or point, used to depict “point” objects or such, scale which cannot be expressed on a map (for example, to show settlements - dots or circles, the size of which indicates a certain population size); linear for objects of a linear nature, preserving the similarity of the outlines of the object (for example, an image of a permanent watercourse in the form of a line, the thickness of which increases downstream); areal, used to fill the areas of objects expressed at the scale of the map (for example, shading or filling with color to show the distribution of forests). These three classes of signs can be further subdivided according to whether the objects they represent are imaginary (eg political boundaries) or real (roads); whether the signs themselves are homogeneous (points on the map, each of which corresponds to a certain number of inhabitants) or differentially representing the quantitative characteristics of objects (depicting cities using circles of different sizes, corresponding to the population size); do they provide a qualitative characteristic of an object (for example, the presence of a swamp) or contain quantitative information (for example, population density - the number of people per unit area).

The purpose of the legend is to inform the reader about the meaning of the symbols used. In old maps, the legend was placed in an elaborately ornamented frame in the form of a scroll, but now in a strict rectangular frame.

As an example, the legend to the geographical maps contained in the Around the World Encyclopedia is given.

Inscriptions and geographical names on maps.

In the past, all labeling was done by hand, giving each map a personal touch, but now cartographers tend to choose one of the standard fonts that best suits the character of the features depicted. Some types of fonts are traditionally used for certain groups of objects, for example, rivers, lakes, seas are usually written in italics, and land relief elements are indicated in roman font. The size of the letters depends on the significance (or size) of the object. The distances between letters and words in names can vary widely depending on the area or extent of a given object on the map.

The font design of the map includes a title, which reflects the content of the map and the territory to which it relates; For this purpose, the largest font is used. A special place is occupied by geographical names, the selection and number of which depend on the purpose of the map (for example, a city plan contains many street names, but vegetation maps contain only a few of the most necessary names). It is customary to indicate the publishing organization, year of publication, and sources used. The map is accompanied by a legend, which explains the symbols, and sometimes with notes.

Map orientation

in relation to the countries of the world is determined by the lines of the cartographic grid within the map frame and represents an essential element of its layout. In the Middle Ages, both in Europe and in Arab countries, maps were drawn in such a way that the east was located at the top (the term “orientation” itself comes from the Latin word oriens - east). In modern maps, north is usually placed at the top of the map, although deviations from this rule are sometimes allowed. Reading a map, especially in the field, is greatly facilitated by its correct orientation relative to objects and directions on the ground. To indicate the cardinal points, a compass card is sometimes depicted on the map, but more often it is simply an arrow pointing to the north.

TYPES OF CARDS

Maps are divided into groups according to a number of characteristics - scale, subject matter, territorial coverage, projection, etc. However, any correctly carried out classification must take into account at least the first two signs. In the United States, there are three groups of scale: large-scale maps (including topographic), medium-scale and small-scale, or overview.

Large scale maps

are basic because they provide primary information used in compiling maps of medium and small scales. The most common of these are topographic maps at a scale larger than 1:250,000.

On modern topographic maps, relief is usually shown using isohypses, or contour lines, that connect points that have the same height above ground level (usually sea level). The combination of such lines gives a very expressive picture of the relief of the earth's surface and makes it possible to determine the following characteristics: angle of inclination, slope profile and relative elevations. In addition to depicting the relief, topographic maps contain other useful information. They usually show transport routes, populated areas, political and administrative borders. The set of additional information (for example, the distribution of forests, swamps, loose sandy massifs, etc.) depends on the purpose of the maps and the characteristic features of the area.

No country needing to assess its natural resources can do without topographic surveying, which is greatly facilitated by the use of aerial photographs. Nevertheless, there are still no topographic maps for many areas of the globe, so necessary for engineering purposes. Progress in solving this problem has been achieved with the help of the so-called. orthophotomaps. As the basis for orthophoto maps, computer-processed planned aerial photographs with increased brightness of colors and contour lines, boundaries, geographical names, etc. are used on them. Orthophoto maps and satellite images with elements of topographic load raised on them are much less labor-intensive to produce than traditional topographic maps. Many thematic large-scale maps - geological, soil, vegetation and land use - use topographic maps as a base on which a special load is applied. Other specialized large-scale maps, such as cadastral maps or city plans, may not have a topographic basis. Usually on such maps the relief is either not shown at all or is depicted very schematically.

Medium-scale maps.

Both large-scale topographic maps and medium-scale maps are usually produced in sets, each of which meets specific requirements. Most medium-scale ones are published for regional planning or navigation needs. The medium-scale International World Map and US aeronautical maps have the greatest territorial coverage. Both sets of maps are produced at a scale of 1:1,000,000, which is the most common scale for medium-scale maps. When preparing the International World Map, each country issues maps on its territory prepared in accordance with specified general requirements. This work is coordinated by the UN, but many maps are out of date and others are not yet completed. The content of the International World Map basically corresponds to the content of topographic maps, but is more generalized. The same applies to aeronautical maps of the world, but most sheets of these maps have an additional special load applied to them. Aeronautical maps cover the entire landmass. Some nautical or hydrographic maps are also compiled at a medium scale, with special attention paid to the depiction of bodies of water and coastlines. Some administrative and road maps are also at medium scale.

Small-scale, or overview, maps.

Small-scale maps show the entire surface of the globe or a significant part of it. It is difficult to precisely define the boundary between small and medium scale maps, but the 1:10,000,000 scale definitely applies to overview maps. Most atlas maps are on a small scale, and thematically they can be very different. Almost all of the above groups of objects can be reflected on small-scale maps, provided that the information is sufficiently generalized. In addition, maps of the distribution of various languages, religions, crops, climatic conditions, etc. are compiled on a small scale. A good example of special small-scale maps that are familiar to millions of people is weather maps.

Cartoon and computer cards.

For cartoon cards that can be projected onto a television screen, the fourth coordinate is entered - time , allowing you to trace the dynamics mapped object . Computer mapping has now reached such a stage of development that almost all operations can be performed digitally. As a result, it is significantly easier to make all kinds of corrections and clarifications. This method of creating maps of any type and scale, including cartoon maps, is designated by the special term “geographic information systems” (GIS).

MAIN TYPES OF PROJECTIONS

A map projection is a way of displaying the spherical surface of the globe on a plane. The associated image transformation inevitably leads to distortion. However, some characteristics of the cartographic grid applied to the surface of the globe are can be saved on the card at the expense of other characteristics that will be distorted.

On the globe, all parallels and meridians intersect at right angles. A projection in which this property is preserved is called conformal, or equiangular. In this case, the shape of the area objects is preserved, but the relative sizes change from place to place. With another conversion method, it is possible to maintain the correct ratio of areas (corresponding to the original surface of the globe), but in these cases there is a distortion of the angles of intersection of meridians and parallels; right angles are maintained only in a limited area. Projections in which the correct ratio of the areas of individual cells of the degree grid are preserved are called equal-area; they are characterized by a greater or lesser violation of the similarity of figures. The correct transfer of the configuration of objects, as well as the correct transfer of areas, are of great importance, especially when it comes to small-scale overview maps. However, both of these characteristics cannot be combined on the same map: there is no projection that would be both equiangular and equal in area. In addition, the correct display of distances and directions is very important. To some extent this can be achieved by using certain projections.

Map projections can be classified according to the type of auxiliary geometric surface that can be used in its construction. Let's take a transparent globe with lines of meridians and parallels applied to its surface and a point source of light. We can enclose a globe (with the light source located at the center of the ball) in a cylinder. In this case, the degree grid is projected onto the surface of the cylinder, which can then be unfolded on the plane. The cylinder can be tangent and touch the globe only along one line (for example, the equator), or it can be secant. In the latter case, the surfaces of the ball and the cylinder will coincide along two lines (for example, along 45° N and 45° S), and only along these lines is the correct scale maintained in this projection. By changing the position of the light source relative to the surface of the ball, different projections of the mapping grid can be obtained on the surface of a cylinder or other geometric figure.

One such shape traditionally used in map projections is the cone. As in the previous case, the cone can touch the ball or cut it. The lines along which these figures touch or cut each other (usually certain parallels) maintain the correct scale and are standard parallels. To reduce distortion, you can use a series of truncated cones instead of a single cone; in this case, the correct transfer of scales along a number of standard parallels will be achieved.

In the cases considered, a development on the plane of a cylinder or cone is necessary, but, of course, it is also possible to directly project the surface of the ball onto the plane. In this case, the plane can touch the ball at one point or cut it; in the latter case, the surfaces of the ball and the plane will coincide along the line of the circle. This transformation of the degree grid is called an azimuthal projection; in it, the true scale is preserved only at the point of contact or at the line of intersection of the plane and the sphere. The configuration of the resulting grid on the projection depends on the position of the light source.

In accordance with the geometric figures used in constructing the projections considered, the latter are called cylindrical (or rectangular), conical and azimuthal. In addition to those indicated, other transformations of the degree grid are possible, not reducible to these simple geometric forms, but having a mathematical justification; they are usually called arbitrary. Many projections have been developed at different times, but only a few of them have come into widespread use. The cartographer's task is to select a projection that best suits the objectives of a given map.

A distinctive feature of stereographic projection is that all objects that are circles on the earth's surface are also depicted on the map as circles or, in some special cases, as straight lines. It is thanks to this property that stereographic projection, invented in ancient times, is so widely used now, for example, to show the propagation of radio waves, etc.

The Mercator projection is conformal. Any straight line that intersects all meridians at the same angle on the earth's surface is conveyed in this projection by a straight line, which is called a loxodrome. This remarkable property makes the Mercator projection very convenient for navigational charts. Unfortunately, this projection is often used erroneously to show areas such as the global distribution of population, crops, etc.

In such cases, it is most appropriate to choose equal-area projections, for example, sinusoidal. This projection, one of many developed for world maps, has a certain defect - both poles on it are located on protrusions, and the areas adjacent to them are significantly deformed. On other maps of the world that use equal area projections, the poles are depicted as a straight line of varying lengths (in cylindrical projections it is equal to the equator, in the Eckert IV projection - half the length of the equator, in a flat polar projection - a third of the equator), or even in the form of an arc (Mollweide projection ). The characteristics of some projections are given in the table ( see below). The list of projections included in the table is far from complete and does not include, for example, polar equidistant and polar equidistant (both are azimuthal), as well as some projections that make it possible to most accurately reproduce the surface of the globe, for example, orthographic.

One of the most convenient projections - gnomonic - is unique in the sense that any great circle of a sphere (and the arc of a great circle) is depicted in it as a straight line. Since the arcs of great circles are the lines of the shortest distances on the map, using a small-scale map drawn up in such a projection, you can easily find (using a ruler) the shortest paths between two points; however, it is necessary to keep in mind What the arc of a great circle does not follow a constant direction as measured by a compass. As in other azimuthal projections, in the gnomonic projection the image can be projected onto a plane tangent to the surface of the ball at any point, for example at the pole or at the equator, but the territorial coverage of such maps is very limited.

The Bonn Equal Area Projection is more suitable for depicting areas elongated in the meridional direction. If the mapped territory is elongated in latitude, then the Lambert conformal conic projection is preferable for it. The polyconic projection is neither conformal nor equal area, but for small areas it produces minor distortions; It is in this projection that a series of maps prepared by the US Geological Survey and Cartography Service are compiled, as well as (with minor modifications) the International Map of the World. Another equal-area projection, developed for overview maps, combines the features of sinusoidal (when transmitting equatorial regions) and pseudocylindrical Mollweide projections (in the polar regions). As in a number of other equal-area projections, the image in it can be given with gaps or in a compressed form.

Discontinuities arise if not one average (straight-line) meridian is selected, but several, and for each of them a part of the degree grid is constructed. An extreme case is the depiction of the entire surface of the globe in the form of globe segments. Maps in this projection also use a “compressed” image; compression is achieved due to the fact that parts of the image that are not needed for a given map (for example, water areas for a soil cover map) are “cut out”, and the remaining ones are brought together; this makes it possible to use a larger scale while maintaining the same sheet area.

METHODS OF MAPPING

Once a projection has been selected and its corresponding degree grid has been drawn, you can begin to draw up the basis and prepare the information that determines the content of the map. At the same time, aerial photographs are often used for large-scale maps. Theoretically, a planned aerial photograph contains all the landscape elements that can be shown on a large-scale map. Moreover, having photographs that partially overlap each other, it is possible to construct relief maps in contour lines; This requires a stereoscope and various instruments for measuring heights from photographs. The development of photogrammetry, a science that deals with measuring and mapping the earth's surface using aerial photographs, has made it possible to significantly speed up the compilation of maps and increase their accuracy. The use of aerial and satellite imagery has made it easier to update outdated maps. Although aerial photographs provide a good representation of the surface, they are still no substitute for maps; they contain a lot of “unsorted” information, so they require interpretation. On a map, relatively less important data can be omitted, while other, more significant for the purposes of this map, on the contrary, are highlighted for easier reading. Moreover, both within one image and in different images of the same series, there are various distortions of the image and violations of its scale. Therefore, in order to use images to compile detailed maps, they must be brought to a single scale and corrected.

Some mapping problems can be illustrated by the example of coastlines that delimit land and water areas. Because there are tides, the boundaries of continents and oceans change in accordance with changes in sea level; maps usually show their position at mean sea level (i.e., the average between high and low tide levels). In addition, even the largest scale maps cannot show all the details of the coastline; therefore, generalization is necessary.

The meaning of generalization, i.e. selection and generalization of details, increases as the scale of maps decreases; Almost all elements of the basis and content of the map are subject to generalization. For example, of the streams shown on a large-scale topographic map, only a few can be preserved on a medium-scale map; When moving to overview maps, further selection and reduction of the number of elements is required. When selecting and generalizing, it is also necessary to establish selection principles - for example, when choosing criteria for displaying settlements, it is necessary to decide whether to be guided only by population size or also take into account the political significance of cities; in the latter case, it is necessary to show all capital cities on the map, although their population may be low.

One of the most difficult tasks in mapping is getting the terrain right. In this case, methods such as washing, drawing relief forms, isohypses, shading and layer-by-layer hypsometric painting are used. Contour lines can be thought of as lines where a topographic surface intersects a series of equally spaced horizontal planes; the vertical distances between these planes are called the horizontal section. Being a quantitative indicator, contour lines are very informative, however, this method has some disadvantages - for example, small relief forms may not be reflected on the map even with a small section, and, in addition, the relief in such an image is not very clear. In some cases, difficulties are overcome with the help of plastic washing - in addition to contour lines, shadows are applied to the relief image in accordance with the main skeletal lines, giving a qualitative characteristic, i.e. distribution of light and shadow under a given (oblique or vertical) lighting. A similar effect can be obtained when photographing an illuminated relief model. Theoretically, even very small landforms can be shown using shadow hillshading, if they are expressed at all at a given scale. The combination of horizontals and washing achieves the most accurate qualitative and quantitative representation of surface shapes.

Showing the relief through strokes differs in that the strokes are drawn along the dip of the slope (and not along the strike, like horizontal lines). The thickness of the strokes depends on the angle of the slope; the greater the slope, the thicker the line, causing steeper slopes to appear darker on the map. Using shading, you can show sharp ridges and steep ledges; When drawing horizontal lines, even the most careful ones, these shapes usually look smoothed out. The use of echo sounding allows for detailed mapping of the topography of the ocean floor.

The oldest method of showing the outlines of the earth's surface is the use of perspective symbols, which are a stylized image of certain relief forms in profile or in a 3/4 perspective. In this case, their appearance, naturally, differs from the plan image characteristic of the map, and accordingly, some of them turn out to be shifted in relation to the true coordinates. This shift is tolerable on overview maps, but is unacceptable for large-scale maps. Therefore, schematic symbols depicting landforms are usually used only on small-scale maps. Previously, only the largest objects were transferred in this way; modern physiographic maps also show small forms. In this case, it is necessary to exaggerate the vertical scale compared to the horizontal, since otherwise the relief forms look excessively flat and inexpressive.

The depiction of relief on hypsometric maps represents the highest degree of generalization of the contour lines method. Like depicting landforms with stylized perspective marks, this method is used primarily on survey maps. On hypsometric maps, each altitude zone is painted with a certain color (or shade). A line can be drawn along the contact of two high-rise steps, highlighted in different colors. Moreover, in each individual altitudinal zone, which sometimes covers hundreds of vertical meters, many details of the relief structure are not reflected on the map.

Traditionally, a specific color scale was used to compile hypsometric maps, in which shades of green, yellow and brown succeeded each other in order of increasing height; some cartographers are now abandoning this. However, there is a tradition of depicting a number of mapped objects in a certain color. For example, brown is used for contours, blue for water features, red for populated areas, and green for vegetation. Using color not only makes the map more attractive, but also allows you to present additional information.

Statistical maps.

Small-scale statistical maps deserve special mention due to their growing importance. These maps are usually based on sources containing quantitative information, such as census data. Among the methods of transmitting information, one should indicate the point method, isopleth, choropleth (cartogram) and cartogram methods. All of these methods can be used for the same data. Dot icons of the same size, each of which represents the same number of units of the depicted phenomenon , are plotted on the map according to the actual location of the phenomenon; the accumulation or sparseness of points shows the distribution (density) of the phenomenon being mapped. Isopleths are isolines connecting points with the same values ​​of some relative indicator, calculated on the basis of other indicators (rather than measured directly). An example is the isolines of average monthly temperatures (calculated indicator). In the choropleth system, a specific territorial statistical unit (for example, an administrative district) is considered homogeneous for a given statistical indicator; spatial differentiation is achieved by the fact that the selected units are divided into classes according to the size of the mapped feature and each class is assigned a specific color. On map diagrams, areas that are statistically homogeneous with respect to the selected attribute are shown regardless of the boundaries of the territorial units, the data for which are used as the basis for the map.

Two more methods often used for statistical maps are signs, the size of which depends on the quantitative characteristics of the phenomenon being depicted, and signs showing the direction of movement. In the first method, used in the case of precisely localized phenomena, such as urban populations, the point signs have different weights; the size of signs is chosen proportional to their weight and has several gradations (for example, according to the number of residents of cities). Signs of movement may also include quantitative characteristics (for example, the volume of maritime transport). This effect is achieved by changing the thickness of the lines.

HISTORY OF CARTOGRAPHY DEVELOPMENT

The universality of the cards is evidenced by the fact that even the so-called. primitive peoples make maps perfectly suited to their needs. For example, the Eskimos, without any measuring instruments, drew up maps of large areas of northern Canada, which do not lose much when compared with maps of the same territories compiled using modern methods. Likewise, the nautical charts compiled by the inhabitants of the Marshall Islands provide extremely interesting examples of "primitive" cartography. In these maps, the "grid" is formed by the midribs of the palm leaves, representing the open sea, and the arcuate side veins correspond to the front of the waves approaching the islands; The islands themselves are marked with mollusk shells. There is a growing interest in Aboriginal maps, including American Indians.

In addition to rock paintings, the oldest maps compiled in Babylon and ancient Egypt have reached us. Babylonian clay tablet maps dating from around 2500 BC show features ranging in size from a single landholding to a major river valley. On the lid of one Egyptian sarcophagus is a stylized map of the roads of ancient Egypt. Chinese cartography also dates back to ancient times. China developed some very important techniques a long time ago and independently of the West, including the rectangular mapping grid used to determine the location of an object.

As for ancient Greece, although we have only a few examples of maps from this era, it is known from literary sources that the Greeks were significantly superior to other peoples in this area. Already in the 4th century. BC. The Greeks came to the conclusion that the Earth was spherical and divided it into climatic zones, from which the concept of latitude later arose. Eratosthenes in the 3rd century. BC. using simple geometric constructions, he amazingly accurately determined the size of the Earth. He also owned a map of the world, which showed lines of latitude and longitude (although not in the modern orderly form). The depiction of geographic coordinates in the form of a regular grid at equal intervals, attributed to the Greek astronomer Hipparchus, was used by the famous Greek cartographer Ptolemy, who lived in the 2nd century. AD in Alexandria. Ptolemy compiled a gazetteer that included ca. 8,000 points indicating their coordinates, and developed a manual for drawing maps, according to which many centuries later scientists were able to reconstruct some of the maps he compiled. After Ptolemy, cartography in the West fell into decline, although the Romans carried out extensive work on surveying lands And drawing up road maps.

Significant progress in cartography was achieved in China: compiled there in the 12th century. the maps are superior to any others dating from this time. It is China that is credited with issuing the first printed map ca. 1150 ( see fig.). Meanwhile, the Arabs, using data from astronomical observations, learned to determine the latitude and longitude of any place much more accurately than Ptolemy was able to do. Most of the maps drawn up in Europe in the Middle Ages were either extremely schematic, such as road maps for pilgrims, or were overloaded with religious symbolism. The most common cards were the "T to O" type; The earth on them was depicted in the form of a disk, with the letter “O” representing the ocean surrounding the land; the vertical stroke of the letter "T" represented the Mediterranean Sea, and the Nile and Don rivers constituted the right and left parts of the upper crossbar, respectively. These water bodies divided Asia (located at the top of the map), Africa and Europe on the map.

At the beginning of the 14th century. A new type of map has appeared in cartography. These were nautical charts - portolans, which served navigational purposes; their creation became possible thanks to the advent of the magnetic compass in Europe. Initially, these maps, decorated with a schematic depiction of a compass and distinguished by exceptionally detailed elaboration of coastlines, were compiled only for the Mediterranean. In some respects, the pinnacle of medieval cartography can be considered the small globe made by Martin Beheim in 1492, showing the world as it appeared before the discovery of America. This is the oldest globe.

Great geographical discoveries of Europeans in the second half of the 15th century. provided Renaissance cartographers with new material. At the same time, scholars rediscovered and translated from the ancient Greek the works of Ptolemy, the dissemination of which was made possible by printing. The development of printing revolutionized cartography, making maps much more accessible. In the Netherlands in particular, card production has increased sharply. A central role in this process was played by Gerard Mercator (1512–1594), who clarified the position of many points on the world map, developed cartographic projections and created a major atlas, published after his death. The first atlas in the modern sense was a collection of maps published by the Flemish Abraham Ortelius under the title Spectacle of the globe (Theatrum orbis terrarum). The success of these ventures led to a boom in the card trade; in subsequent centuries the industry declined due to a lack of new ideas.

A new impetus to the development of cartography was given in the 17th century. as a result of the activities of newly formed scientific societies, such as the Royal Society of London or the Royal Academy of Sciences in Paris. These organizations financed scientific expeditions, and also made a lot of effort to more accurately determine the shape of the Earth and the location of individual points, which contributed to significant progress in cartography. A significant role in the development of topographic cartography was played by the invention of the theodolite, mensula, barometer and pendulum clock, as well as the development of new imaging methods (isolines, shading, etc.). Modern topographical surveying on a national scale began in France in the 18th century.

In the 19th century There have been notable advances in small-scale mapping and especially in the development of quantitative cartography. At the end of the 19th century. German geographer Albrecht Penck spoke at the International Geographical Congress with a proposal to create an International Map of the World. This project was carried out in the 20th century. The use of aerial photographs has become widespread in this century. Ideas about the structure of the earth's surface and the shape of the Earth have been significantly enriched thanks to observations from artificial satellites, from which materials for mapping other celestial bodies were obtained.

ORGANIZATIONS AND ENTERPRISES ENGAGED IN THE COMPILATION AND PUBLISHING OF MAPS

Mapping the earth's surface has been and remains the domain of various international organizations. For example, the UN, in addition to funding the International World Map, allocates funds to map-making organizations. The international exchange of cartographic information is facilitated by the International Cartographic Association, which holds regular meetings and publishes a reference yearbook ( The International Yearbook of Cartography). Another international publication, the magazine “Imago Mundi” (translated as “Image of the World”), is dedicated to the history of cartography.

Topographic survey of the territories of individual countries is usually carried out by the forces of these countries. In many countries, national geodetic and topographical work originally served military purposes; An example is the UK Filming Service, responsible for the preparation of topographic maps of the territory of this country. In the United States, there are more than a dozen federal organizations involved in topographic surveys throughout the country; the largest of them is the US Geological Survey and Cartography Service, whose main residence is in Washington. Surveying the US coastline and providing the geodetic basis necessary for this is the responsibility of the US Coast and Geodetic Survey. Among other US mapping organizations, mention should be made of the Department of Defense Surveying and Cartography Agency, which deals with topographic, hydrographic and aerospace surveys. Many countries produce national atlases, the creation of which is carried out by various organizations, partially or fully funded by the government.

In some countries, geographical societies periodically issue thematic maps as supplements to their periodicals. The US Geographical Society, for example, features a variety of political and thematic maps in most issues of its popular magazine National Geographic.

Commercial mapping enterprises often specialize in the production of a particular type of cartographic product. Some produce road maps, others produce wall maps and atlases for schools, colleges and universities, while others specialize in publishing cadastral maps for the needs of lawyers, tax inspectors, etc. The center for commercial publishing of maps in the United States is located in Chicago. In many countries, such enterprises are located in the capitals. Collecting cards, especially old ones, is widespread in the United States. A special magazine “The Map Collector” is published for collectors. Facsimile copies of many ancient maps and atlases are available for sale.

In the United States, the most complete collection of maps and atlases, including both modern and ancient editions issued in various countries, is located in the cartographic department of the Library of Congress in Washington. Copies of maps issued by US federal agencies, as well as handwritten maps produced by the same agencies, are kept at the National Archives and Records Administration in Washington. The same functions in Great Britain and France are performed, respectively, by the cartographic department of the British Library in London and the National Library in Paris. The Vatican Library in Rome has a large collection of ancient and very valuable maps.

Literature:

Salishchev K.A. Cartography. M., 1976
Berlyant A.M. Cartographic research method. M., 1978
Brief topographic-geodetic dictionary. M., 1979
Salishchev K.A. Cartography. M., 1982
Berlyant A.M. Image of space: map and computer science. M., 1986

Without it, it is impossible to construct a single geographical map. What is scale? And what types of scales exist in cartography and geodesy? This will be discussed in this article.

What is scale?

Scale is a German word (masstab), which consists of two parts: mass - “measure, magnitude” and stab - “stick, pole”. Measuring pole - this is how this term can be translated.

What is scale? In a general interpretation, this is a mathematical value that shows how many times the model (image) is reduced in comparison to the original. This concept is actively used in mathematics, cartography, modeling, geodesy and design, photography, and programming.

In other words, scale is the ratio of two linear dimensions. In cartography, it shows how many times a segment on a map (or plan) is reduced compared to the actual length of the same segment. When compiling any geographical map, it is impossible to depict objects (forest, village, building, etc.) in real size. Therefore, all values ​​are reduced many times (by 5, 10, 100, 1000 times, and so on). The scale of the map is precisely this value expressed as a number.

Types of scales

Scale is shown on maps and drawings using numbers or graphically. Accordingly, several types are distinguished.

The numerical scale is in the form of a fraction. It is most common in cartography. Many of us have seen this designation at the bottom of a topographic map or area plan. The numerical scale of the map has the following form (for example): 1:100,000. This means that the real length of the segment on the ground is 100,000 times greater than its length on this map.

A named scale is used when you need to know what the map scale is. It is also quite often indicated on geographical maps. It looks like this: 1 cm - 1 km.

Linear scale is already a graphic type of scale. It is a ruler, which is divided into columns of appropriate sizes. The photo above shows this type of scale.

Transverse scale is a more sophisticated version of the graphical view. It is used for the most accurate measurements and can be found on more serious maps.

How to use map scale correctly? Suppose you need to use a specific map to find out the real distance between villages A and B. In this case, you are given the following scale: 1 cm - 0.5 km (or 1:50,000). To do this, you need to take a regular ruler and measure the distance between two points on the map. Then the resulting value (suppose this is a segment 5 centimeters long) should be multiplied by 0.5 km, according to the scale of our map. Thus, we will get the correct answer: the distance between village A and village B is 2.5 kilometers.

Types of maps (by scale)

Scale is one of the criteria for classifying geographic maps. So, according to him, all cards are divided into:

• small-scale (scale up to 1:1,000,000);
• medium-scale (from 1:1,000,000 to 1:200,000);
• large-scale (from 1:200,000 and more).

Of course, on large-scale maps the terrain is more detailed: individual streets or even buildings can be shown here. The larger the scale of the map, the more terrain objects can be depicted on it.

Small-scale geographic maps, as a rule, are used to depict hemispheres and continents, medium-scale - for states and their parts, large-scale - for individual, small areas. Military personnel, local historians, and tourists are very familiar with large-scale maps.

Cartographic generalization

No matter how detailed the map is, it still will not be able to display absolutely all the objects and details that are present in a given area. This is precisely the essence of the concept of “cartographic generalization”.

The word generalis can be translated from Latin as “generalized.” Generalization is the process of selecting those geographical objects that will be depicted on a specific map. Moreover, this process is objective, expedient and scientifically sound.

To understand what generalization is, it is enough to remember the cards that you probably held in your hands. So, on the map of Eurasia you are unlikely to find the city of Cherepovets. But it will definitely be marked on the map of the Vologda region.

Cartographic generalization helps to make the map of the highest quality, functional, and easy to read. Of course, it directly depends on the scale.

Finally

So what is scale? This value shows how reduced the image is compared to the actual size of the imaged object. This concept is most widespread in cartography and geography. There are several types of scales: numerical, named, linear and transverse.

The concept of cartographic generalization is closely related to the term “scale”. This process allows surveyors to select important geographic features and display them on a geographic map.

The content of the article

MAP, a reduced generalized image of the Earth's surface (or part of it) on a plane. Man has been creating maps since ancient times, trying to visualize the relative location of various areas of land and seas. A collection of maps, usually bound together, is called an atlas, a term coined by the Flemish Renaissance cartographer Gerardus Mercator.

A ball (sphere) with a cartographic image of the Earth applied to its surface is called a globe. This is the most accurate representation of the earth's surface. All maps that provide an image of a ball on a plane have some kind of distortion that cannot be eliminated. However, maps have certain advantages over the globe. For example, a world map allows you to look at the entire earth's surface (i.e., its image), while on a globe no more than half of the globe is visible from one point; therefore, maps are more convenient when considering the entire surface of the Earth. In addition, it is much easier to measure angles and directions on a map than on a globe. Currently, globes are rarely used for navigation purposes. Depicting territories on a spherical surface that are no larger than the subcontinent does not provide virtually any advantages, which is why in such cases maps are used rather than segments of the globe. Moreover, maps are much easier to make, transport and store (although some of these difficulties can be overcome by using inflatable globes).

KEY FEATURES OF THE CARDS

Despite the amazing variety of existing maps, most of them share some common features. Even contour maps, which are designed to be as lightweight as possible so that students can add additional information of their choice, usually have a grid, scale, and datum features (such as coastlines). In addition, the cards are usually marked with inscriptions and symbols, and a legend is attached to them.

Coordinate grid

is a system of mutually intersecting lines indicating latitude and longitude on a map or the surface of a globe. Lines indicating latitude run in the east-west direction parallel to the equator (whose latitude is 0°); The latitude of the poles is considered equal to 90° (north latitude for the North Pole and south latitude for the South Pole). Since these lines do not intersect and are mutually parallel, they are also called parallels. Of these, only the equator is the largest circle (the plane bounded by this line, passing through the center of the Earth, cuts the globe in half). The remaining parallels are circles, the length of which naturally decreases with distance from the equator. All lines of longitude - meridians - are halves of a large circle, converging at the poles. The meridians run in the north-south direction, from pole to pole; the angular distance is calculated from them from the prime meridian, designated as 0° longitude, to the east and west to 180° (in this case, longitudes that are measured in the eastern direction are designated by the letters “E”, and in the western direction - “W.” d.") . Unlike the equator, which is equidistant from the poles throughout and is in this sense a “natural” reference point when determining latitude, the prime meridian from which longitude is measured is chosen arbitrarily. In accordance with international agreement, the meridian of the Greenwich Astronomical Observatory (now located in London) is taken as the origin of coordinates (0° longitude). However, before this agreement was reached, some cartographers used the Canary or Azores Islands, Paris, Philadelphia, Rome, Tokyo, Pulkovo, etc. as prime meridians.

On the surface of the globe, the lines of parallels and meridians intersect at an angle of 90°; As for maps, this ratio is preserved only in some cases. Both on maps and on globes a certain system of meridians and parallels (drawn at 5°, 10°, 15° or 30°) is usually marked. In addition to this, maps and globes show the Tropic of Cancer (23 1/2 ° N), the Tropic of Capricorn (23 1/2 ° S), and the Arctic Circle ( 66 1/2°N) and the Antarctic Circle (66 1/2°S). Often maps are also marked with the International Date Line, which generally coincides with 180° of longitude.

Scale

cards can be numerical (ratio of numbers or fraction, for example, 1:25,000 or 1/25,000); verbal or linear (graphic). In the example given, a unit of length on the map corresponds to 25,000 such units on the ground. The same ratio can be expressed in the words: “1 cm is equal to 250 m” or, even shorter: “there are 250 m in 1 cm.” In some countries that traditionally use non-metric measures of length (USA, etc.), the scale is expressed in inches, feet and miles, for example, 1:63,360 or “1 inch is 1 mile.” A linear scale is depicted as a line with divisions marked at certain intervals, against which the corresponding distances on the earth's surface are indicated. The graphical representation of scale has certain advantages over the other two ways of expressing it. In particular, if the size of the map changes when it is copied or projected onto the screen, then only the graphical scale, which undergoes changes along with the entire map, remains correct. Sometimes, in addition to the length scale, the area scale is also used. Globes may use any of the scale symbols above.

Basic elements and conventional cartographic signs.

The elements of the geographical basis include the image of the coastline, watercourses, political boundaries, etc., which create the basis against which the spatial distribution of the displayed phenomenon is shown. When compiling maps, many symbols are used, which are divided into several categories: non-scale, or point, used to depict “point” objects or such, scale which cannot be expressed on a map (for example, to show settlements - dots or circles, the size of which indicates a certain population size); linear for objects of a linear nature, preserving the similarity of the outlines of the object (for example, an image of a permanent watercourse in the form of a line, the thickness of which increases downstream); areal, used to fill the areas of objects expressed at the scale of the map (for example, shading or filling with color to show the distribution of forests). These three classes of signs can be further subdivided according to whether the objects they represent are imaginary (eg political boundaries) or real (roads); whether the signs themselves are homogeneous (points on the map, each of which corresponds to a certain number of inhabitants) or differentially representing the quantitative characteristics of objects (depicting cities using circles of different sizes, corresponding to the population size); do they provide a qualitative characteristic of an object (for example, the presence of a swamp) or contain quantitative information (for example, population density - the number of people per unit area).

The purpose of the legend is to inform the reader about the meaning of the symbols used. In old maps, the legend was placed in an elaborately ornamented frame in the form of a scroll, but now in a strict rectangular frame.

As an example, the legend to the geographical maps contained in the Around the World Encyclopedia is given.

Inscriptions and geographical names on maps.

In the past, all labeling was done by hand, giving each map a personal touch, but now cartographers tend to choose one of the standard fonts that best suits the character of the features depicted. Some types of fonts are traditionally used for certain groups of objects, for example, rivers, lakes, seas are usually written in italics, and land relief elements are indicated in roman font. The size of the letters depends on the significance (or size) of the object. The distances between letters and words in names can vary widely depending on the area or extent of a given object on the map.

The font design of the map includes a title, which reflects the content of the map and the territory to which it relates; For this purpose, the largest font is used. A special place is occupied by geographical names, the selection and number of which depend on the purpose of the map (for example, a city plan contains many street names, but vegetation maps contain only a few of the most necessary names). It is customary to indicate the publishing organization, year of publication, and sources used. The map is accompanied by a legend, which explains the symbols, and sometimes with notes.

Map orientation

in relation to the countries of the world is determined by the lines of the cartographic grid within the map frame and represents an essential element of its layout. In the Middle Ages, both in Europe and in Arab countries, maps were drawn in such a way that the east was located at the top (the term “orientation” itself comes from the Latin word oriens - east). In modern maps, north is usually placed at the top of the map, although deviations from this rule are sometimes allowed. Reading a map, especially in the field, is greatly facilitated by its correct orientation relative to objects and directions on the ground. To indicate the cardinal points, a compass card is sometimes depicted on the map, but more often it is simply an arrow pointing to the north.

TYPES OF CARDS

Maps are divided into groups according to a number of characteristics - scale, subject matter, territorial coverage, projection, etc. However, any correctly carried out classification must take into account at least the first two signs. In the United States, there are three groups of scale: large-scale maps (including topographic), medium-scale and small-scale, or overview.

Large scale maps

are basic because they provide primary information used in compiling maps of medium and small scales. The most common of these are topographic maps at a scale larger than 1:250,000.

On modern topographic maps, relief is usually shown using isohypses, or contour lines, that connect points that have the same height above ground level (usually sea level). The combination of such lines gives a very expressive picture of the relief of the earth's surface and makes it possible to determine the following characteristics: angle of inclination, slope profile and relative elevations. In addition to depicting the relief, topographic maps contain other useful information. They usually show transport routes, populated areas, political and administrative borders. The set of additional information (for example, the distribution of forests, swamps, loose sandy massifs, etc.) depends on the purpose of the maps and the characteristic features of the area.

No country needing to assess its natural resources can do without topographic surveying, which is greatly facilitated by the use of aerial photographs. Nevertheless, there are still no topographic maps for many areas of the globe, so necessary for engineering purposes. Progress in solving this problem has been achieved with the help of the so-called. orthophotomaps. As the basis for orthophoto maps, computer-processed planned aerial photographs with increased brightness of colors and contour lines, boundaries, geographical names, etc. are used on them. Orthophoto maps and satellite images with elements of topographic load raised on them are much less labor-intensive to produce than traditional topographic maps. Many thematic large-scale maps - geological, soil, vegetation and land use - use topographic maps as a base on which a special load is applied. Other specialized large-scale maps, such as cadastral maps or city plans, may not have a topographic basis. Usually on such maps the relief is either not shown at all or is depicted very schematically.

Medium-scale maps.

Both large-scale topographic maps and medium-scale maps are usually produced in sets, each of which meets specific requirements. Most medium-scale ones are published for regional planning or navigation needs. The medium-scale International World Map and US aeronautical maps have the greatest territorial coverage. Both sets of maps are produced at a scale of 1:1,000,000, which is the most common scale for medium-scale maps. When preparing the International World Map, each country issues maps on its territory prepared in accordance with specified general requirements. This work is coordinated by the UN, but many maps are out of date and others are not yet completed. The content of the International World Map basically corresponds to the content of topographic maps, but is more generalized. The same applies to aeronautical maps of the world, but most sheets of these maps have an additional special load applied to them. Aeronautical maps cover the entire landmass. Some nautical or hydrographic maps are also compiled at a medium scale, with special attention paid to the depiction of bodies of water and coastlines. Some administrative and road maps are also at medium scale.

Small-scale, or overview, maps.

Small-scale maps show the entire surface of the globe or a significant part of it. It is difficult to precisely define the boundary between small and medium scale maps, but the 1:10,000,000 scale definitely applies to overview maps. Most atlas maps are on a small scale, and thematically they can be very different. Almost all of the above groups of objects can be reflected on small-scale maps, provided that the information is sufficiently generalized. In addition, maps of the distribution of various languages, religions, crops, climatic conditions, etc. are compiled on a small scale. A good example of special small-scale maps that are familiar to millions of people is weather maps.

Cartoon and computer cards.

For cartoon cards that can be projected onto a television screen, the fourth coordinate is entered - time , allowing you to trace the dynamics mapped object . Computer mapping has now reached such a stage of development that almost all operations can be performed digitally. As a result, it is significantly easier to make all kinds of corrections and clarifications. This method of creating maps of any type and scale, including cartoon maps, is designated by the special term “geographic information systems” (GIS).

MAIN TYPES OF PROJECTIONS

A map projection is a way of displaying the spherical surface of the globe on a plane. The associated image transformation inevitably leads to distortion. However, some characteristics of the cartographic grid applied to the surface of the globe are can be saved on the card at the expense of other characteristics that will be distorted.

On the globe, all parallels and meridians intersect at right angles. A projection in which this property is preserved is called conformal, or equiangular. In this case, the shape of the area objects is preserved, but the relative sizes change from place to place. With another conversion method, it is possible to maintain the correct ratio of areas (corresponding to the original surface of the globe), but in these cases there is a distortion of the angles of intersection of meridians and parallels; right angles are maintained only in a limited area. Projections in which the correct ratio of the areas of individual cells of the degree grid are preserved are called equal-area; they are characterized by a greater or lesser violation of the similarity of figures. The correct transfer of the configuration of objects, as well as the correct transfer of areas, are of great importance, especially when it comes to small-scale overview maps. However, both of these characteristics cannot be combined on the same map: there is no projection that would be both equiangular and equal in area. In addition, the correct display of distances and directions is very important. To some extent this can be achieved by using certain projections.

Map projections can be classified according to the type of auxiliary geometric surface that can be used in its construction. Let's take a transparent globe with lines of meridians and parallels applied to its surface and a point source of light. We can enclose a globe (with the light source located at the center of the ball) in a cylinder. In this case, the degree grid is projected onto the surface of the cylinder, which can then be unfolded on the plane. The cylinder can be tangent and touch the globe only along one line (for example, the equator), or it can be secant. In the latter case, the surfaces of the ball and the cylinder will coincide along two lines (for example, along 45° N and 45° S), and only along these lines is the correct scale maintained in this projection. By changing the position of the light source relative to the surface of the ball, different projections of the mapping grid can be obtained on the surface of a cylinder or other geometric figure.

One such shape traditionally used in map projections is the cone. As in the previous case, the cone can touch the ball or cut it. The lines along which these figures touch or cut each other (usually certain parallels) maintain the correct scale and are standard parallels. To reduce distortion, you can use a series of truncated cones instead of a single cone; in this case, the correct transfer of scales along a number of standard parallels will be achieved.

In the cases considered, a development on the plane of a cylinder or cone is necessary, but, of course, it is also possible to directly project the surface of the ball onto the plane. In this case, the plane can touch the ball at one point or cut it; in the latter case, the surfaces of the ball and the plane will coincide along the line of the circle. This transformation of the degree grid is called an azimuthal projection; in it, the true scale is preserved only at the point of contact or at the line of intersection of the plane and the sphere. The configuration of the resulting grid on the projection depends on the position of the light source.

In accordance with the geometric figures used in constructing the projections considered, the latter are called cylindrical (or rectangular), conical and azimuthal. In addition to those indicated, other transformations of the degree grid are possible, not reducible to these simple geometric forms, but having a mathematical justification; they are usually called arbitrary. Many projections have been developed at different times, but only a few of them have come into widespread use. The cartographer's task is to select a projection that best suits the objectives of a given map.

A distinctive feature of stereographic projection is that all objects that are circles on the earth's surface are also depicted on the map as circles or, in some special cases, as straight lines. It is thanks to this property that stereographic projection, invented in ancient times, is so widely used now, for example, to show the propagation of radio waves, etc.

The Mercator projection is conformal. Any straight line that intersects all meridians at the same angle on the earth's surface is conveyed in this projection by a straight line, which is called a loxodrome. This remarkable property makes the Mercator projection very convenient for navigational charts. Unfortunately, this projection is often used erroneously to show areas such as the global distribution of population, crops, etc.

In such cases, it is most appropriate to choose equal-area projections, for example, sinusoidal. This projection, one of many developed for world maps, has a certain defect - both poles on it are located on protrusions, and the areas adjacent to them are significantly deformed. On other maps of the world that use equal area projections, the poles are depicted as a straight line of varying lengths (in cylindrical projections it is equal to the equator, in the Eckert IV projection - half the length of the equator, in a flat polar projection - a third of the equator), or even in the form of an arc (Mollweide projection ). The characteristics of some projections are given in the table ( see below). The list of projections included in the table is far from complete and does not include, for example, polar equidistant and polar equidistant (both are azimuthal), as well as some projections that make it possible to most accurately reproduce the surface of the globe, for example, orthographic.

One of the most convenient projections - gnomonic - is unique in the sense that any great circle of a sphere (and the arc of a great circle) is depicted in it as a straight line. Since the arcs of great circles are the lines of the shortest distances on the map, using a small-scale map drawn up in such a projection, you can easily find (using a ruler) the shortest paths between two points; however, it is necessary to keep in mind What the arc of a great circle does not follow a constant direction as measured by a compass. As in other azimuthal projections, in the gnomonic projection the image can be projected onto a plane tangent to the surface of the ball at any point, for example at the pole or at the equator, but the territorial coverage of such maps is very limited.

The Bonn Equal Area Projection is more suitable for depicting areas elongated in the meridional direction. If the mapped territory is elongated in latitude, then the Lambert conformal conic projection is preferable for it. The polyconic projection is neither conformal nor equal area, but for small areas it produces minor distortions; It is in this projection that a series of maps prepared by the US Geological Survey and Cartography Service are compiled, as well as (with minor modifications) the International Map of the World. Another equal-area projection, developed for overview maps, combines the features of sinusoidal (when transmitting equatorial regions) and pseudocylindrical Mollweide projections (in the polar regions). As in a number of other equal-area projections, the image in it can be given with gaps or in a compressed form.

Discontinuities arise if not one average (straight-line) meridian is selected, but several, and for each of them a part of the degree grid is constructed. An extreme case is the depiction of the entire surface of the globe in the form of globe segments. Maps in this projection also use a “compressed” image; compression is achieved due to the fact that parts of the image that are not needed for a given map (for example, water areas for a soil cover map) are “cut out”, and the remaining ones are brought together; this makes it possible to use a larger scale while maintaining the same sheet area.

METHODS OF MAPPING

Once a projection has been selected and its corresponding degree grid has been drawn, you can begin to draw up the basis and prepare the information that determines the content of the map. At the same time, aerial photographs are often used for large-scale maps. Theoretically, a planned aerial photograph contains all the landscape elements that can be shown on a large-scale map. Moreover, having photographs that partially overlap each other, it is possible to construct relief maps in contour lines; This requires a stereoscope and various instruments for measuring heights from photographs. The development of photogrammetry, a science that deals with measuring and mapping the earth's surface using aerial photographs, has made it possible to significantly speed up the compilation of maps and increase their accuracy. The use of aerial and satellite imagery has made it easier to update outdated maps. Although aerial photographs provide a good representation of the surface, they are still no substitute for maps; they contain a lot of “unsorted” information, so they require interpretation. On a map, relatively less important data can be omitted, while other, more significant for the purposes of this map, on the contrary, are highlighted for easier reading. Moreover, both within one image and in different images of the same series, there are various distortions of the image and violations of its scale. Therefore, in order to use images to compile detailed maps, they must be brought to a single scale and corrected.

Some mapping problems can be illustrated by the example of coastlines that delimit land and water areas. Because there are tides, the boundaries of continents and oceans change in accordance with changes in sea level; maps usually show their position at mean sea level (i.e., the average between high and low tide levels). In addition, even the largest scale maps cannot show all the details of the coastline; therefore, generalization is necessary.

The meaning of generalization, i.e. selection and generalization of details, increases as the scale of maps decreases; Almost all elements of the basis and content of the map are subject to generalization. For example, of the streams shown on a large-scale topographic map, only a few can be preserved on a medium-scale map; When moving to overview maps, further selection and reduction of the number of elements is required. When selecting and generalizing, it is also necessary to establish selection principles - for example, when choosing criteria for displaying settlements, it is necessary to decide whether to be guided only by population size or also take into account the political significance of cities; in the latter case, it is necessary to show all capital cities on the map, although their population may be low.

One of the most difficult tasks in mapping is getting the terrain right. In this case, methods such as washing, drawing relief forms, isohypses, shading and layer-by-layer hypsometric painting are used. Contour lines can be thought of as lines where a topographic surface intersects a series of equally spaced horizontal planes; the vertical distances between these planes are called the horizontal section. Being a quantitative indicator, contour lines are very informative, however, this method has some disadvantages - for example, small relief forms may not be reflected on the map even with a small section, and, in addition, the relief in such an image is not very clear. In some cases, difficulties are overcome with the help of plastic washing - in addition to contour lines, shadows are applied to the relief image in accordance with the main skeletal lines, giving a qualitative characteristic, i.e. distribution of light and shadow under a given (oblique or vertical) lighting. A similar effect can be obtained when photographing an illuminated relief model. Theoretically, even very small landforms can be shown using shadow hillshading, if they are expressed at all at a given scale. The combination of horizontals and washing achieves the most accurate qualitative and quantitative representation of surface shapes.

Showing the relief through strokes differs in that the strokes are drawn along the dip of the slope (and not along the strike, like horizontal lines). The thickness of the strokes depends on the angle of the slope; the greater the slope, the thicker the line, causing steeper slopes to appear darker on the map. Using shading, you can show sharp ridges and steep ledges; When drawing horizontal lines, even the most careful ones, these shapes usually look smoothed out. The use of echo sounding allows for detailed mapping of the topography of the ocean floor.

The oldest method of showing the outlines of the earth's surface is the use of perspective symbols, which are a stylized image of certain relief forms in profile or in a 3/4 perspective. In this case, their appearance, naturally, differs from the plan image characteristic of the map, and accordingly, some of them turn out to be shifted in relation to the true coordinates. This shift is tolerable on overview maps, but is unacceptable for large-scale maps. Therefore, schematic symbols depicting landforms are usually used only on small-scale maps. Previously, only the largest objects were transferred in this way; modern physiographic maps also show small forms. In this case, it is necessary to exaggerate the vertical scale compared to the horizontal, since otherwise the relief forms look excessively flat and inexpressive.

The depiction of relief on hypsometric maps represents the highest degree of generalization of the contour lines method. Like depicting landforms with stylized perspective marks, this method is used primarily on survey maps. On hypsometric maps, each altitude zone is painted with a certain color (or shade). A line can be drawn along the contact of two high-rise steps, highlighted in different colors. Moreover, in each individual altitudinal zone, which sometimes covers hundreds of vertical meters, many details of the relief structure are not reflected on the map.

Traditionally, a specific color scale was used to compile hypsometric maps, in which shades of green, yellow and brown succeeded each other in order of increasing height; some cartographers are now abandoning this. However, there is a tradition of depicting a number of mapped objects in a certain color. For example, brown is used for contours, blue for water features, red for populated areas, and green for vegetation. Using color not only makes the map more attractive, but also allows you to present additional information.

Statistical maps.

Small-scale statistical maps deserve special mention due to their growing importance. These maps are usually based on sources containing quantitative information, such as census data. Among the methods of transmitting information, one should indicate the point method, isopleth, choropleth (cartogram) and cartogram methods. All of these methods can be used for the same data. Dot icons of the same size, each of which represents the same number of units of the depicted phenomenon , are plotted on the map according to the actual location of the phenomenon; the accumulation or sparseness of points shows the distribution (density) of the phenomenon being mapped. Isopleths are isolines connecting points with the same values ​​of some relative indicator, calculated on the basis of other indicators (rather than measured directly). An example is the isolines of average monthly temperatures (calculated indicator). In the choropleth system, a specific territorial statistical unit (for example, an administrative district) is considered homogeneous for a given statistical indicator; spatial differentiation is achieved by the fact that the selected units are divided into classes according to the size of the mapped feature and each class is assigned a specific color. On map diagrams, areas that are statistically homogeneous with respect to the selected attribute are shown regardless of the boundaries of the territorial units, the data for which are used as the basis for the map.

Two more methods often used for statistical maps are signs, the size of which depends on the quantitative characteristics of the phenomenon being depicted, and signs showing the direction of movement. In the first method, used in the case of precisely localized phenomena, such as urban populations, the point signs have different weights; the size of signs is chosen proportional to their weight and has several gradations (for example, according to the number of residents of cities). Signs of movement may also include quantitative characteristics (for example, the volume of maritime transport). This effect is achieved by changing the thickness of the lines.

HISTORY OF CARTOGRAPHY DEVELOPMENT

The universality of the cards is evidenced by the fact that even the so-called. primitive peoples make maps perfectly suited to their needs. For example, the Eskimos, without any measuring instruments, drew up maps of large areas of northern Canada, which do not lose much when compared with maps of the same territories compiled using modern methods. Likewise, the nautical charts compiled by the inhabitants of the Marshall Islands provide extremely interesting examples of "primitive" cartography. In these maps, the "grid" is formed by the midribs of the palm leaves, representing the open sea, and the arcuate side veins correspond to the front of the waves approaching the islands; The islands themselves are marked with mollusk shells. There is a growing interest in Aboriginal maps, including American Indians.

In addition to rock paintings, the oldest maps compiled in Babylon and ancient Egypt have reached us. Babylonian clay tablet maps dating from around 2500 BC show features ranging in size from a single landholding to a major river valley. On the lid of one Egyptian sarcophagus is a stylized map of the roads of ancient Egypt. Chinese cartography also dates back to ancient times. China developed some very important techniques a long time ago and independently of the West, including the rectangular mapping grid used to determine the location of an object.

As for ancient Greece, although we have only a few examples of maps from this era, it is known from literary sources that the Greeks were significantly superior to other peoples in this area. Already in the 4th century. BC. The Greeks came to the conclusion that the Earth was spherical and divided it into climatic zones, from which the concept of latitude later arose. Eratosthenes in the 3rd century. BC. using simple geometric constructions, he amazingly accurately determined the size of the Earth. He also owned a map of the world, which showed lines of latitude and longitude (although not in the modern orderly form). The depiction of geographic coordinates in the form of a regular grid at equal intervals, attributed to the Greek astronomer Hipparchus, was used by the famous Greek cartographer Ptolemy, who lived in the 2nd century. AD in Alexandria. Ptolemy compiled a gazetteer that included ca. 8,000 points indicating their coordinates, and developed a manual for drawing maps, according to which many centuries later scientists were able to reconstruct some of the maps he compiled. After Ptolemy, cartography in the West fell into decline, although the Romans carried out extensive work on surveying lands And drawing up road maps.

Significant progress in cartography was achieved in China: compiled there in the 12th century. the maps are superior to any others dating from this time. It is China that is credited with issuing the first printed map ca. 1150 ( see fig.). Meanwhile, the Arabs, using data from astronomical observations, learned to determine the latitude and longitude of any place much more accurately than Ptolemy was able to do. Most of the maps drawn up in Europe in the Middle Ages were either extremely schematic, such as road maps for pilgrims, or were overloaded with religious symbolism. The most common cards were the "T to O" type; The earth on them was depicted in the form of a disk, with the letter “O” representing the ocean surrounding the land; the vertical stroke of the letter "T" represented the Mediterranean Sea, and the Nile and Don rivers constituted the right and left parts of the upper crossbar, respectively. These water bodies divided Asia (located at the top of the map), Africa and Europe on the map.

At the beginning of the 14th century. A new type of map has appeared in cartography. These were nautical charts - portolans, which served navigational purposes; their creation became possible thanks to the advent of the magnetic compass in Europe. Initially, these maps, decorated with a schematic depiction of a compass and distinguished by exceptionally detailed elaboration of coastlines, were compiled only for the Mediterranean. In some respects, the pinnacle of medieval cartography can be considered the small globe made by Martin Beheim in 1492, showing the world as it appeared before the discovery of America. This is the oldest globe.

Great geographical discoveries of Europeans in the second half of the 15th century. provided Renaissance cartographers with new material. At the same time, scholars rediscovered and translated from the ancient Greek the works of Ptolemy, the dissemination of which was made possible by printing. The development of printing revolutionized cartography, making maps much more accessible. In the Netherlands in particular, card production has increased sharply. A central role in this process was played by Gerard Mercator (1512–1594), who clarified the position of many points on the world map, developed cartographic projections and created a major atlas, published after his death. The first atlas in the modern sense was a collection of maps published by the Flemish Abraham Ortelius under the title Spectacle of the globe (Theatrum orbis terrarum). The success of these ventures led to a boom in the card trade; in subsequent centuries the industry declined due to a lack of new ideas.

A new impetus to the development of cartography was given in the 17th century. as a result of the activities of newly formed scientific societies, such as the Royal Society of London or the Royal Academy of Sciences in Paris. These organizations financed scientific expeditions, and also made a lot of effort to more accurately determine the shape of the Earth and the location of individual points, which contributed to significant progress in cartography. A significant role in the development of topographic cartography was played by the invention of the theodolite, mensula, barometer and pendulum clock, as well as the development of new imaging methods (isolines, shading, etc.). Modern topographical surveying on a national scale began in France in the 18th century.

In the 19th century There have been notable advances in small-scale mapping and especially in the development of quantitative cartography. At the end of the 19th century. German geographer Albrecht Penck spoke at the International Geographical Congress with a proposal to create an International Map of the World. This project was carried out in the 20th century. The use of aerial photographs has become widespread in this century. Ideas about the structure of the earth's surface and the shape of the Earth have been significantly enriched thanks to observations from artificial satellites, from which materials for mapping other celestial bodies were obtained.

ORGANIZATIONS AND ENTERPRISES ENGAGED IN THE COMPILATION AND PUBLISHING OF MAPS

Mapping the earth's surface has been and remains the domain of various international organizations. For example, the UN, in addition to funding the International World Map, allocates funds to map-making organizations. The international exchange of cartographic information is facilitated by the International Cartographic Association, which holds regular meetings and publishes a reference yearbook ( The International Yearbook of Cartography). Another international publication, the magazine “Imago Mundi” (translated as “Image of the World”), is dedicated to the history of cartography.

Topographic survey of the territories of individual countries is usually carried out by the forces of these countries. In many countries, national geodetic and topographical work originally served military purposes; An example is the UK Filming Service, responsible for the preparation of topographic maps of the territory of this country. In the United States, there are more than a dozen federal organizations involved in topographic surveys throughout the country; the largest of them is the US Geological Survey and Cartography Service, whose main residence is in Washington. Surveying the US coastline and providing the geodetic basis necessary for this is the responsibility of the US Coast and Geodetic Survey. Among other US mapping organizations, mention should be made of the Department of Defense Surveying and Cartography Agency, which deals with topographic, hydrographic and aerospace surveys. Many countries produce national atlases, the creation of which is carried out by various organizations, partially or fully funded by the government.

In some countries, geographical societies periodically issue thematic maps as supplements to their periodicals. The US Geographical Society, for example, features a variety of political and thematic maps in most issues of its popular magazine National Geographic.

Commercial mapping enterprises often specialize in the production of a particular type of cartographic product. Some produce road maps, others produce wall maps and atlases for schools, colleges and universities, while others specialize in publishing cadastral maps for the needs of lawyers, tax inspectors, etc. The center for commercial publishing of maps in the United States is located in Chicago. In many countries, such enterprises are located in the capitals. Collecting cards, especially old ones, is widespread in the United States. A special magazine “The Map Collector” is published for collectors. Facsimile copies of many ancient maps and atlases are available for sale.

In the United States, the most complete collection of maps and atlases, including both modern and ancient editions issued in various countries, is located in the cartographic department of the Library of Congress in Washington. Copies of maps issued by US federal agencies, as well as handwritten maps produced by the same agencies, are kept at the National Archives and Records Administration in Washington. The same functions in Great Britain and France are performed, respectively, by the cartographic department of the British Library in London and the National Library in Paris. The Vatican Library in Rome has a large collection of ancient and very valuable maps.

Literature:

Salishchev K.A. Cartography. M., 1976
Berlyant A.M. Cartographic research method. M., 1978
Brief topographic-geodetic dictionary. M., 1979
Salishchev K.A. Cartography. M., 1982
Berlyant A.M. Image of space: map and computer science. M., 1986