Prepare translation of the main text

Military Topography

Cartography is the art and science of expressing the known physical features of the earth graphically by maps and charts. Today, the complexities of tactical operations and deployment of troops are such that it is essential for all soldiers to be able to read and interpret the maps in order to move quickly and effectively on the battlefield. To complement map reading procedures, a mastery of field movement techniques is necessary. Soldiers must know how to determine locations of points on a map, measure distances and azimuths, and identify military symbols on a map. The symbols used to represent such military features as identity, size, location, or movement of soldiers; and military activities and installations are known as military symbols. These symbols resemble, as closely as possible, the actual features themselves as viewed from above. The simplest way to measure ground distance is the pace count. A pace is equal to one natural step, about 30 inches long. To accurately use the pace count method, you must know how many paces it takes you to walk 100 meters.

Maps

A map is a graphic representation of a portion of the earth's surface drawn to scale, as seen from above. It uses topographic map symbols, and labels to represent features found on the ground. It is impossible to plot every feature of the area in true shape. An attempt to plot each feature true to scale would result in a product impossible to read even with the aid of a magnifying glass. A map indicates variations in terrain, heights of natural shape and linear features, and the extent of vegetation cover. A map provides information on the existence, the location of, and the distance between urban area and routes of travel and communication. Map requisitions and distributions are accomplished through the Defense Mapping Agency.

To be understandable, features must be represented by conventional signs and symbols. To be legible, many of these must be exaggerated in size often far beyond the actual ground limits of the feature represented.

Еlevation and Relief

The elevation of points on the ground and the relief of an area affect the movement and positioning of military units. Relief is the representation of the shapes of hills, valleys, streams, or terrain features on the earth's surface. Mapmakers use several methods to depict relief of the terrain. Layer tinting is a method of showing relief by color. Hachures are short, broken lines used to show relief. Relief shading indicates relief by a shadow effect achieved by tone and color. A contour line is an imaginary line on the ground, above or below mean sea level which represents vertical positions or relief. The elevations and contours are measured from a specific vertical datum plane.

Scale

The scale is expressed as a fraction and gives the ratio of map distance to ground distance. The numerical scale of a map indicates the relationship of distance measured on a map and the corresponding distance on the ground. This scale is usually written as a fraction and is called the representative fraction.

According to the Defense Mapping Agency maps are classified by scale into three categories. They're small­, medium­, and large-scale maps. The terms small scale, medium scale and large scale may be confusing when read in conjunction with the numbers. However, if the number is viewed as a fraction, it quickly becomes apparent that 1:600,000 of something is smaller than 1:75,000 of the same thing. These maps with scales of 1:75,000 and larger are used for tactical, administrative, and logistical planning. The standard small scale map is 1:1,000,000. This scale map covers a very large ground area, so mapmaker has hardly any room for details. Medium maps are used for planning operations, including the movement and concentration of troops and combat vehicles. The standard large scale map is 1:50,000. A graphic scale is a ruler printed on the map and is used to convert distances on the map to actual ground distances. On a 1:250,000 scale map, the prescribed symbol for a building covers an area about 500 feet square on the ground; a road symbol is equivalent to a road about 520 feet wide on the ground; the symbol for a single-track railroad is equivalent to a railroad cross-tie about 1,000 feet on the ground.

 

Types

The map of choice for land navigation is the 1:50,000-scale military topographic map. All maps are subdivided by types. Planimetric map is a map that presents only the horizontal positions for the features represented. Sometimes, it is called a line map. It is distinguished from a topographic map by the omission of relief, normally represented by contour lines. Photomap is a reproduction of an aerial photograph upon which grid lines, marginal data, route numbers, and approximate scale and direction have been added. Photomosaic is an assembly of aerial photographs, when time does not permit the compilation of a more accurate map.

Terrain model provides a means for visualizing the terrain for planning and for briefing on assault landing. Military city map is a topographic map showing urban elements of military importance that are compatible with the scale of map. A special purpose map has been designed to give information not covered on a standard map. Some of the subjects covered are: terrain features, drainage characteristics, vegetation, coasts and landing beaches, urban areas, cross-country movements.

Marginal information

All maps are not the same so it becomes necessary every time a different map is used to examine the marginal information carefully. Legend is one of important map requisitions which assist a map reader to interpret military maps. The map's legend contains the symbols most commonly used in a particular series or on that specific topographic map sheet.

Sheet numbers are based on an arbitrary system that makes possible the ready orientation of maps of relevant scales. It is used as a reference number to link operations, situation or other specific maps to overlays, operations orders, and plans.

Elevation guide provides the map reader with a means of rapid recognition of major land forms. This is normally found in the lower right margin.

In recent edition maps, there is a note indicating the conversion of azimuths from grid to magnetic and from magnetic to grid next to the declination diagram. This is located in the lower margin of large-scale maps and indicates the angular relationships of TN, GN, and MN.

Bar scales are rulers used to convert map distance to ground distance. Maps have three or more bar scales, each in a different unit of measure.

Contour interval note states the vertical distance between adjacent contour lines and when supplementary contours are used, the interval is indicated.

Geographic Coordinate and Grid Coordinate

One of the oldest systematic methods of location is based upon the geographic coordinate system. The distance of a point north or south of the equator is known as its latitude. The rings around the earth parallel to the equator are called parallels. A second set of rings around the globe passing through the poles is known as meridians of longitude. A meridian is designated as the PM. The four lines that enclose the body of the map are latitude and longitude lines.

The U.S. Army military grid reference system reduces the length of written coordinates by substituting single letters for several numbers. Based on the military principle for reading maps (RIGHT and UP), locations on the map can be determined by grid coordinates. Each of grid lines is labeled at both ends of the map with its false easting or false northing (distance north of the equator) value.

Map classification

Maps are documents that must not fall into unauthorized hands. All maps should be considered as documents, classified or unclassified, requiring special handling. If a map is in danger of being captured, it must be destroyed. The best method of destruction is by burning it and scattering the ashes. If burning is not possible, the map can be torn into small pieces and scattered over a wide area. The U.S. Government has three security classifications: “Confidential”, “Restricted”, and “Top Secret”. This is shown in the upper and lower margins.

Aerial Photographs

The aerial photograph has many uses in military operations; however, they are considered primarily as a map supplement or map substitute. An aerial photograph is any photograph taken from an airborne vehicle (aircraft, drones, balloons, satellites, and so forth). Aerial photography may be divided into two major types, the vertical and the oblique. Vertical aerial photography is taken over flat terrain and used for the purpose of updating field sketches. Оblique аerial photography is used primarily in the making of aeronautical charts. Low oblique does not show the horizon. In high oblique the horizon is always visible. They are used to study an area before an attack, to substitute for a reconnaissance. A topographic map may be obsolete because it was compiled many years ago. However, the aerial photograph has the following disadvantages as compared to a map: ground features are difficult to interpret without symbols; it lacks marginal data; position location and scale are only approximate.