Military Topographic Map I

Large Scale Maps

- Are used for tactical, administrative, and logistical planning. - These are the maps a Marine or junior leader are most likely to encounter. - Large-scale maps are 1:75,000 and larger.

Military Map Substitutes

- Foreign Maps - Atlases - Geographic Maps - Tourist Road Maps - City/Utility Maps - Field Sketches

Other Types of Maps

- Planimetric maps - Digital maps - Photomap - Terrain Model - Military City Map

Small Scale Maps

- Used for general planning and for strategic studies. - Covers a large area at the expense of detail. - Small-scale maps are 1:1,000,000 and smaller.

Medium Scale Maps

- Used for operational planning. - Contain moderate amount of detail, but terrain analysis is best done with the large-scale maps. - Medium-scale maps are between 1:75,000 and 1:1,000,000.

Topographic Map

A topographic map portrays terrain features in a measurable way, as well as the horizontal positions of the features represented. The vertical positions, or relief, are normally represented by contour lines on military topographic maps. On maps showing relief, the elevations and contours are measured from a specific vertical datum plane, usually, mean sea level.

Grid Reference System

A uniform and precise system of referencing developed to cope with difficulty of finding undeveloped areas.

Stock Number Identification

All maps published by the NGA that are in the department of the Army map supply system contain stock number identification that are used in requisitioning map supplies

Locating A Point Using MGRS

Always read RIGHT and then UP

Marginal Information: Red

Classifies cultural features such as populated areas, main roads, and boundaries on older maps

Marginal Information: Red-Brown/Gray

Cultural features, all relief features, non-surveyed spot elecations, and elevation such as contour lines on red-light readable maps. The color gray is also used to make maps readable under blue or green light

Contour Interval Note

Found in the center of the lower margin normally below the bar scales. It states the vertical distance between adjacent contour lines of the map. When supplementary contours are used, the interval is indicated. In recent edition maps, the contour interval is given in meters instead of feet.

Marginal Information: Brown

IDs all relief features and elevation such as contours on older edition maps, and cultivated land on red-light readable maps

Marginal Information: Blue

IDs hydrography or water features such as lakes, swamps, rivers, and drainage

Marginal Information: Green

IDs vegetation with military significance such as woods, orchards, and vineyards

Marginal Information: Black

Indicates cultural (man-made) features such as buildings and roads, surveyed spot elevations, and all labels

Preparation Note

Located at the center of the lower margin. Indicates agency responsible for preparing the map

Horizontal Datum Note

Located in the center lower margin. Defined as a geodetic reference point (of which five qualities are known: latitude, longitude, azimuth of a line from this point, and two constants, which are the parameters of reference ellipsoid). These are the basis for horizontal control surveys. The horizontal control datum may extend over a continent or be limited to a small local area. Maps and charts produced by NGA are produced on 32 different horizontal control data. Map readers should habitually check the horizontal datum note on every map or chart, especially adjacent map sheets, to ensure the products are based on the same horizontal datum. If products are based on a different horizontal control data, coordinate transformations to a common datum is performed. UTM coordinates from the same point computed on different data may differ as much as 900 meters

Printing Note

Located in the center of the lower margin. Indicates agency responsible for printing the map and the date the map was printed. The printing data should not be used to determine when the map information was obtained

Control Note

Located in the center of the lower margin. Indicates the special agencies involved in the control of the technical aspects of all the information that is disseminated on the map

Spheroid

Located in the center of the lower margin. Spheroids have specific parameters that define the XYZ axis of the earth. The spheroid is an integral part of the datum

Vertical Datum Note

Located in the center of the lower margin. The vertical datum or vertical control datum is defined as a level surface taken as a surface of reference from which to determine elevations. In the US, Canada, and Europe, the vertical datum refers to the mean sea level surface. However, in parts of Asia and Africa, the vertical control datum may vary locally and is based on an assumed elevation that has no connection to the sea level surface. Map readers should habitually check the vertical datum note on maps, particularly if the map is used for low-level aircraft navigation, naval gunfire support, or missile target acquisition

Bar Scales

Located in the center of the lower margin. They are rulers used to convert map distances to ground distance. Maps have three or more bar scales, each in a different unit of measure. Care should be exercised when using the scales, especially in the selection of the unit of measure that is needed.

Legend

Located in the lower left margin. It illustrates and identifies the topographic symbols used to depict some of the more prominent features on the map. The symbols are not always the same on every map. Always refer to the legend to avoid errors when reading a map.

Declination Diagram

Located in the lower margin of large-scale maps and indicates the angular relationships of true north, grid north, and magnetic north. 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

Unit Imprint and Symbol

Located on the left side of the lower margin and identifies the agency that prepared and printed the map and its respective symbol. This information is important to the map user in evaluating the reliability of the map

Determining Grids With a Coordinate Scale

Make sure that the appropriate scale is being used on the corresponding map, and the scale is right side up. When reading coordinate, examine the two sides of the coordinate scale to ensure that the horizontal line of the scale is aligned with the east-west grid line, and the vertical line of the scale is parallel with the north-south grid line.

Adjoining Sheets Diagram

Maps are all standard scales contain a diagram that illustrates the adjoining sheets. It consists of as many rectangles representing the adjoining sheets as are necessary to surround the rectangle that represents the sheet under consideration. The diagram usually contains nine rectangles, but the number may vary depending on the locations of the adjoining sheets, All represented sheets are identified by their sheet numbers. Sheets of an adjoining series, whether by their sheet numbers. Sheets of an adjoining series, whether published or planned, that are at the same scale are represented by dashed lines. The series number of the adjoining series is indicated along the appropriate side of the division line between the series.

Grid Reference Box

Normally located in the center of the lower margin. Contains instructions for composing a grid reference

User's Note

Normally located in the lower right hand margin. Requests cooperation in the correcting errors or omissions on the map. Errors should be marked and the map forwarded to the agency identified in the note

Representative Fraction

Numerical scale of a map indicates the relationship of distance measured on a map and the corresponding distance to the ground. Usually written as a fraction and is called the representative fraction.

Marginal Information: Other

Occasionally, other colors may be used to show special information, As a rule, these are indicated in the marginal information

Universal Polar Stereographic Grid: North Polar Area

Origin of the UPS grid applied to the north polar area is the North Pole. The north-south base line is the line formed by the 0degrees and 180 degree meridians; the east-west base line is formed by the two 90 degree meridians

Determining Grids Without a Coordinate Scale

Refer to the north south grid lines numbered at the bottom margin of a map. Then read RIGHT to the north south grid line that precedes the desired point. Afterwords, refer to the east west grid lines numbered at either side of the map, then move UP to the east west grid line that precedes the desired point.

Graphic Bar Scales

Ruler printed on the map that is used to convert distances on the map to actual ground distances.

Geographic Coordinates: Longitude

Second set of rings that run around the globe at right angles of latitude and passing through poles are known as meridians of longitude. One meridians is established as the prime meridian, which runs through Greenwich, England. The distance east or west of the prime meridian to a point is known as its longitude. Lines run north-south but east-west distances are measured between them

Sheet Name

Sheet name is found in bold print at the center of the top and in the lower left area of the map margin. A map is generally named for the largest settlement contained within the area at the time the map was drawn

Latitude Angular Measurements

Starting at 0 degrees at the equator, the parallels of latitude are numbered to 90 degrees both north and south. The extremities are the North Pole at 90 degrees north latitude and the South Pole at 90 degrees south latitude. Latitude can have the same numerical value north or south of the equator, so the direction N or S is always given.

Longitude Angular Measurements

Starting with 0 degrees at the prime meridian, longitude is measured both east and west around the world. Lines east of the prime meridian are numbered to 180 degrees and identified as east longitude; lines west of the prime meridian are numbered to 180 degrees and identified as west longitude. The direction E or W is always given. The line directly opposite the prime meridian, 180 degrees, may be referred to as either east or west longitude.

Special Notes

Statement of general information that relates to the mapped area. It is normally found in the lower right margin. For example, a particular note could be "this map is red-light readable".

Universal Transverse Mercator Grid (UTM)

System adopted by the US Army for designating rectangular coordinates on large-scale military maps. The UTM is currently used by the US and NATO armed forced. With the advent of inexpensive GPS receivers, many other maps users are adopting the UTM grid system for coordinates that are simpler to used than latitude and longtidue

Geographic Coordinates: Latitude

The distance of a point north or south of the equator is known as its latitude. Runs east to west but north-south distances are measured between them

Edition Number

The edition number is found in bold print in the upper right area of the top margin and the lower left area of the bottom margin. Editions are numbered consecutively; if there is more than one edition, the highest numbered sheet is the most recent. The map information date is found immediately below the word "LEGEND" in the lower lefty margin of the map. This date is important when determining how accurately the map data might be expected to match what is encountered on the ground.

Elevation Guide

The elevation guide is normally found in the lower right margin. It is a miniature characterization of the terrain. The terrain is represented by bands of elevation, spot elevations, and major drainage features. The elevation guide provides the map reader with a means of quick recognition of major land forms

Grid Note

The grid note is located in the center of the lower margin. It gives information pertaining to the grid systems used and the interval between grid lines, and it identifies the UTM grid zone number

Index to Boundaries

The index to boundaries diagram appears in the lower or right margin of all sheets.

Series Name

The map series name is found in bold print in the upper left corner of the margin. The name given to the series is generally that of a major political subdivision such as a state within the United States or a European nation. A map series usually includes a group of similar maps at the same scale and on the same sheet lines or format. They are designed to cover a particular geographic area and may be a group of maps that serve a common purpose, such as military city maps.

Grid Squares

The north south and east west grid lines intersect at 90 degrees, forming grid squares. Normally, the size of one of these grid squares on large-scale maps is 1000 m (1 km)

Universal Polar Stereographic Grid: South Polar Area

The origin of the UPS grid in the south polar area is the South Pole. The base lines are similar to those of the north polar area.

Grid Coordinate Scales

The primary tool for plotting grid coordinates is the grid coordinate scale. This scale divides the grid square more accurately than can be done by estimation and the results are more consistent. When used correctly, it presents less chance for making errors.

Projection Note

The projection system is the framework of the map. For military maps, this framework is of the conformal type; small areas of the surface of the earth retain their true shapes on the projection; measured angles closely approximate true values; and the scale factor is the same in all directions from a point. The projection note is located in the center of the lower margin. The three types of projection notes are: -Between 80 degrees south and 84 degrees north, maps at scales larger than 1:500,000 are based on the transverse Mercator projection. The note reads TRANSVERSE MERCATOR PROJECTION -Between 80 degrees south and 84 north, maps at 1:100,000 scale and smaller are based on standard parallels of the lambert conformal conic projection. The note reads LAMBERT CONFORMAL CONIC PROJECTIONS 36 DEGREES 40 MINUTES NORTH and 39 DEGREES 20 MINUTES NORTH -Maps of the polar regions (south of 80 degrees south and north of 84 degrees north) at 1: 1,000,000 and larger scales are based on the polar stereographic projection. The note reads POLAR STEREOGRAPHIC PROJECTION

Scale

The scale is found in the upper left margin after the series name and in the center of the lower margin. The scale note is a representative fraction that gives the ratio of a map distance to the corresponding distance on the earth's surface. For example, the scale note 1:50,000 indicates that one unit of measure on the map equals 50,000 units of the same measure on the ground.

Series Number

The series number is found in the upper right margin and lower left margin. It is a sequence reference expressed either as a four digit numeral or as a letter followed by a three or four digit numeral.

Sheet Number

The sheet number is found in bold print in the upper right and lower left areas of the margin, and in the center box of the adjoining sheets diagram found in the lower right margin. To link specific maps to overlays, operations, orders, and plans, use the sheet number as reference. For maps at 1:100,000-scale and larger, the sheet numbering system is arbitrary and makes possible the ready orientation of maps at scales of 1:100,000, 1:50,000 and 1:25,000

Value of Coordinates

The values of geographic coordinates, being in units of angular measure, mean more if they are compared with more familiar units of measure. At any point on the earth, the ground distance covered by one degree of latitude is about 111 km or 69 mi; one second is equal to about 30 m or 100 ft. The ground distance covered by one degree of longitude at the equator is also about 111 km, but decreases as one moves north or south, until it becomes zero at the poles.

United States Military Grid Reference System (MGRS)

Used with the UTM and UPS grids. The coordinate value of points in these grids could contain as many as 15 digits if numerals alone were used. The US military grid reference system reduces the length of written coordinates by substituting single letters for several numbers. Using the UTM and UPS grids, it is possible for the location of a point (ID by numbers alone) to be in many different places on the surface of the earth. With the use of the military grid reference system, there is no possibility of this happening.