Land Navigation (with sub-categories)

Land Navigation
INDEX: (Click links to browse directly to the subject within this thread)

• Determine the Grid Coordinates of a Point on a Map (you are here now)
  
• Determine a Magnetic Azimuth Using a Lensatic Compass
  
• Locate a point using the US Army Military Grid Reference System (MGRS)
  
• Measure Distance on a Military Map
• Valley (Major Terrain Feature)
• Saddle (Major Terrain Feature)
• Spur (Minor Terrain Feature)
• Ridge (Major Terrain Feature)
• Hill (Major Terrain Feature)
• Handling A Compass
• Draw (Minor Terrain Feature)
• Depression (Major Terrain Feature)
• Cut and a Fill (Supplementary Terrain Features)
• Cliff (Minor Terrain Feature)
• Interpretation of Terrain Features
• Compute Back Azimuths

Determine the Grid Coordinates of a Point on a Map

CONDITIONS
Given a standard 1:50,000 scale military map, a 1:50,000 grid coordinate scale, pencil, paper, and a point on the map for which coordinates must be determined.

STANDARDS
Determine the six-digit grid coordinates for the point on the map with a 100?meter tolerance (grid coordinates must contain the correct two-letter 100,000 meter-square identifier).

TRAINING AND EVALUATION
Notes: 1. To keep from getting lost, a soldier must know how to find out where he is. A combat area has no street addresses, but a military map can help you identify a location accurately. The map has vertical lines (top to bottom) and horizontal lines (left to right). These lines form small squares 1,000 meters on each side called grid squares.

2. The lines that form grid squares are numbered along the outside edge of the map picture. No two grid squares have the same number.

3. The precision of a point location is shown by the number of digits in the coordinates: the more digits, the more precise the location.

1996- a 1,000-meter grid square.
192961- to the nearest 100 meters.
19269614- to the nearest 10 meters.

1. Look at Figure 5-18. Your address is grid square 1181. How do you know this? Start from the left and read right until you come to 11, the first half of your address. Then read up to 81, the other half. Your address is somewhere in grid square 1181 (A, Figure 5-18).

2. Grid square 1181 gives your general neighborhood, but there is a lot of ground inside that grid square. To make your address more accurate, just add another number to the first half and another number to the second half-so your address has six numbers instead of four.

a. To get those extra numbers, pretend that each grid square has ten lines inside it running north and south, and another 10 running east and west. This makes 100 smaller squares. You can estimate where these imaginary lines are.

b. Suppose you are halfway between grid line 11 and grid line 12. Then the next number is 5 and the first half of your address is 115. Now suppose you are also 3/10 of the way between grid line 81 and grid line 82. Then the second half of your address is 813. (If you were exactly on line 81, the second part would be 810). Your address is 115813 (B, Figure 5-18).​

Figure 5-18. Determining a six-digit grid coordinate.

3. The most accurate way to determine the coordinates of a point on a map is to use a coordinate scale. You do not have to use imaginary lines; you can find the exact coordinates using a Coordinate Scale and Protractor (GTA 5-2-12) (Figure 5-19) or a Plotting Scale (Figure 5-20). Each device has two coordinating scales, 1:25,000 meters and 1:50,000 meters. Make sure you use the correct scale.

Figure 5-19. Coordinate scale and protractor.

a. First, locate the grid square in which the point (for example, Point A, Figure 5-21) is located (the point should already be plotted on the map).

b. The number of the vertical grid line on the left (west) side of the grid square is the first and second digits of the coordinates.

Figure 5-20. Plotting scale.


c. The number of the horizontal grid line on the bottom (south) side of the grid square is the fourth and fifth digits of the coordinates.

d. To determine the third and sixth digits of the coordinates, place the coordinate scale on the bottom horizontal grid line of the grid square containing Point A.

Figure 5-21. Placement of coordinate scale.

e. Check to see that the zeros of the coordinate scale are in the lower left-hand (southwest) corner of the map grid square (Figure 5-21).

f. Slide the scale to the right, keeping the bottom of the scale on the bottom grid line until Point A is under the vertical (right-hand) scale (Figures 5-22 and 5-23). On the bottom scale, the 100-meter mark nearest the vertical grid line provides the third digit, 5. On the vertical scale, the 100-meter mark nearest Point A provides the sixth digit, 3. Therefore, the six-digit grid coordinate is 115813.

Figure 5-22. Alignment of coordinate scale.

Figure 5-23. Alignment of plotting scale.


g. To determine the correct two-letter 100,000?meter square identifier, look at the grid reference box in the margin of the map (Figure 5-24).

h. Place the 100,000-meter square identifier in front of the coordinate, GL 11508133.

Figure 5-24. Grid reference box.


Evaluation Guide:
Determine the Grid Coordinates of a Point on a Military Map

Performance Measures
1. Write down the two-letter 100,000-meter square identifier and the six-digit grid coordinates for the designated point with a 100-meter tolerance.

2. Record the grid coordinates with the correct two-letter 100,000-meter square identifier.


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Determine a Magnetic Azimuth Using a Lensatic Compass

CONDITIONS
Given a compass and a designated point on the ground.

STANDARDS
Determine the correct magnetic azimuth to the designated point within 3 degrees using the compass-to-cheek method, or within 10 degrees using the center-hold method.

TRAINING AND EVALUATION
Training Information Outline
1. Read your compass (Figures 5-25 and 5-26).

a. The floating dial is used to determine the direction in which you are pointing your compass.

b. The outer, "black" ring of numbers and tick marks is used for finding direction in mils.
​

Figure 5-25. Lensatic compass.

Figure 5-26. Lensatic compass floating dial.


c. The inner, "red" ring of numbers and tick marks is used for finding direction in degrees.

(1) There are 360 degrees or 6,400 mils in a circle. These are marked with a tick mark every 5 degrees and 20 mils. However, not every tick mark is numbered. You will have to determine the number for these lines using the numbers that are shown.

(2) To read direction, point the compass in the direction you want to go or want to determine.

(3) Look beneath the index line on the outer glass cover and estimate to the nearest degree or 10 mils the position of the index line over the (red or black) scale.

(4) Be careful to hold the compass still so that the dial remains stationary while you are reading the scale.

(5) In Figure 5-26, the readings are 312 degrees (red scale) and 5,500 mils (black scale).

(6) If you understand these readings and can apply either of the holding and sighting techniques of shooting an azimuth, you will be proficient in performing this task.

2. Shoot an azimuth.

a. Use your compass to determine or follow an azimuth. The arrow on the compass points toward magnetic north. The arrow is also attracted by any mass of metal-a truck, your rifle, your helmet, and even electrical power lines. Thus, be sure you use your compass away from metal objects so it will not give a wrong reading.

b. The lensatic compass must always be held level and firm when sighting on an object and reading an azimuth.

c. There are two methods of holding the lensatic compass and sighting.
(1) Compass-to-cheek method (Figure 5-27). To use this method-



(a) Open the cover to a 90-degree angle to the base. Position the eyepiece at a 45-degree angle to the base.

(b) Place your thumb through the thumb loop, form a steady base with your third and fourth fingers, and extend your index finger along the side of the compass base.

(c) Place the hand holding the compass into the palm of the other hand.

Figure 5-27. Compass-to-cheek method.


(d) Bring both hands up to the face and position the thumb that is through the thumb loop against the cheekbone.

(e) Look through the lens of the eyepiece. If the dial is not in focus, move the eyepiece up or down until the dial is in focus.

(f) Align the sighting slot of the eyepiece with the sighting wire in the cover on the point to which the azimuth is being determined. Look through the lens of the eyepiece and read the azimuth under the index line.

(2) Center-hold method (Figure 5-28). Use this method only when a precise direction is not required:

(a) Open the compass so that the cover forms a straight edge with the base. The lens of the compass is moved out of the way.

Figure 5-28. Center-hold method.


(b) Place your thumb through the thumb loop, form a steady base with your third and fourth fingers, and extend your index finger along the side of the compass.


(c) Place the thumb of the other hand between the eyepiece and the lens, extend the index finger along the remaining side of the compass, wrap the remaining fingers around the fingers of the other hand, and pull your elbows firmly into your sides. This will place the compass between your chin and your belt.

(d) To measure an azimuth, turn your entire body toward the object and point the compass cover directly at the object. Look down and read the azimuth from beneath the fixed black index line. This method can be used at night.

(e) To keep from going in circles when you are land navigating, stop occasionally to check the azimuth along which you are moving. Also, you can move from object to object along your path by shooting an azimuth to each object and then moving to that object. Repeating this process while you navigate should keep you straight.

Evaluation Guide:
Determine a Magnetic Azimuth

Performance Measures
1. Determine a magnetic Azimuth using a lensatic compass.

2. Use the compass-to-cheek method to within three degrees of a designated point.

3. Use the center-hold method within 10 degrees to a designated point.

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Locate a point using the US Army Military Grid Reference System (MGRS)

There is only one rule to remember when reading or reporting grid coordinates, always read to the RIGHT and then UP. The first half of the reported set of coordinate digits represents the left-to-right (easting) grid label, and the second half represents the label as read from the bottom to top (northing). The grid coordinates may represent the location to the nearest 10-, 100-, or 1,000-meter increment.

a. Grid Zone. The number 16 locates a point within zone 16, which is an area 6° wide and extends between 80° S latitude and 84° N latitude (Figure 4-8).

b. Grid Zone Designation. The number and letter combination, 16S, further locates a point within the grid zone designation 16S, which is a quadrangle 6° wide by 8° high. There are 19 of these quads in zone 16. Quad X, which is located between 72° N and 84° N latitude, is 12° high (Figure 4-8).

c. 100,000-Meter Square Identification. The addition of two more letters locates a point within the 100,000-meter grid square. Thus 16SGL (Figure 4-11) locates the point within the 100,000-meter square GL in the grid zone designation 16S. For information on the lettering system of 100,000-meter squares, see TM 5-241-1.

d. 10,000-Meter Square. The breakdown of the US Army military grid reference system continues as each side of the 100,000-meter square is divided into 10 equal parts. This division produces lines that are 10,000 meters apart. Thus the coordinates 16SGL08 would locate a point as shown in Figure 4-20. The 10,000-meter grid lines appear as index (heavier) grid lines on maps at 1:100,000 and larger.


Figure 4-20. The 10,000-meter grid square.

e. 1,000-Meter Square. To obtain 1,000-meter squares, each side of the 10,000-meter square is divided into 10 equal parts. This division appears on large-scale maps as the actual grid lines; they are 1,000 meters apart. On the Columbus map, using coordinates 16SGL0182, the easting 01 and the northing 82 gives the location of the southwest corner of grid square 0182 or to the nearest 1,000 meters of a point on the map (Figure 4-21).


Figure 4-21. The 1,000-meter grid square.

f. 100-Meter Identification. To locate to the nearest 100 meters, the grid coordinate scale can be used to divide the 1,000-meter grid squares into 10 equal parts (Figure 4-22).


Figure 4-22. The 100-meter and 10-meter grid squares.

g. 10-Meter Identification. The grid coordinate scale has divisions every 50 meters on the 1:50,000 scale and every 20 meters on the 1:25,000 scale. These can be used to estimate to the nearest 10 meters and give the location of one point on the earth's surface to the nearest 10 meters.

EXAMPLE: 16SGL01948253 (gas tank) (Figure 4-22).

h. Precision. The precision of a point's location is shown by the number of digits in the coordinates; the more digits, the more precise the location.

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Measure Distance on a Military Map
A graphic scale is a ruler printed on the map and is used to convert distances on the map to actual ground distances. The graphic scale is divided into two parts. To the right of the zero, the scale is marked in full units of measure and is called the primary scale. To the left of the zero, the scale is divided into tenths and is called the extension scale. Most maps have three or more graphic scales, each using a different unit of measure. When using the graphic scale, be sure to use the correct scale for the unit of measure desired.



Using a graphic (bar) scale.

a. To determine straight-line distance between two points on a map, lay a straight-edged piece of paper on the map so that the edge of the paper touches both points and extends past them. Make a tick mark on the edge of the paper at each point.


Transferring map distance to paper strip.

b. To convert the map distance to ground distance, move the paper down to the graphic bar scale, and align the right tick mark (b) with a printed number in the primary scale so that the left tick mark (a) is in the extension scale.



Measuring straight-line map distance.

c. The right tick mark (b) is aligned with the 3,000-meter mark in the primary scale, thus the distance is at least 3,000 meters. To determine the distance between the two points to the nearest 10 meters, look at the extension scale. The extension scale is numbered with zero at the right and increases to the left. When using the extension scale, always read right to left. From the zero left to the beginning of the first shaded area is 100 meters. From the beginning of the shaded square to the end of the shaded square is 100 to 200 meters. From the end of the first shaded square to the beginning of the second shaded square is 200 to 300 meters. Remember, the distance in the extension scale increases from right to left.

d. To determine the distance from the zero to tick mark (a), divide the distance inside the squares into tenths. As you break down the distance between the squares in the extension scale into tenths, you will see that tick mark (a) is aligned with the 950-meter mark. Adding the distance of 3,000 meters determined in the primary scale to the 950 meters you determined by using the extension scale, we find that the total distance between points (a) and (b) is 3,950 meters.

e. To measure distance along a road, stream, or other curved line, the straight edge of a piece of paper is used. In order to avoid confusion concerning the point to begin measuring from and the ending point, an eight-digit coordinate should be given for both the starting and ending points. Place a tick mark on the paper and map at the beginning point from which the curved line is to be measured. Align the edge of the paper along a straight portion and make a tick mark on both map and paper when the edge of the paper leaves the straight portion of the line being measured.



Measuring a curved line.

f. Keeping both tick marks together (on paper and map), place the point of the pencil close to the edge of the paper on the tick mark to hold it in place and pivot the paper until another straight portion of the curved line is aligned with the edge of the paper. Continue in this manner until the measurement is completed.

g. When you have completed measuring the distance, move the paper to the graphic scale to determine the ground distance. The only tick marks you will be measuring the distance between are tick marks (a) and (b). The tick marks in between are not used.

h. There may be times when the distance you measure on the edge of the paper exceeds the graphic scale. In this case, there are different techniques you can use to determine the distance.

(1) One technique is to align the right tick mark (b) with a printed number in the primary scale, in this case the 5. You can see that from point (a) to point (b) is more than 6,000 meters when you add the 1,000 meters in the extension scale. To determine the exact distance to the nearest 10 meters, place a tick mark (c) on the edge of the paper at the end of the extension scale. You know that from point (b) to point (c) is 6,000 meters. With the tick mark (c) placed on the edge of the paper at the end of the extension scale, slide the paper to the right. Remember the distance in the extension is always read from right to left. Align tick mark (c) with zero and then measure the distance between tick marks (a) and (c). The distance between tick marks (a) and (c) is 420 meters. The total ground distance between start and finish points is 6,420 meters.



Determining the exact distance.

(2) Another technique that may be used to determine exact distance between two points when the edge of the paper exceeds the bar scale is to slide the edge of the paper to the right until tick mark (a) is aligned with the edge of the extension scale. Make a tick mark on the paper, in line with the 2,000-meter mark (c). Then slide the edge of the paper to the left until tick mark (b) is aligned with the zero. Estimate the 100-meter increments into 10-meter increments to determine how many meters tick mark (c) is from the zero line. The total distance would be 3,030 meters.



Reading the extension scale.

(3) At times you may want to know the distance from a point on the map to a point off the map. In order to do this, measure the distance from the start point to the edge of the map. The marginal notes give the road distance from the edge of the map to some towns, highways, or junctions off the map. To determine the total distance, add the distance measured on the map to the distance given in the marginal notes. Be sure the unit of measure is the same.

(4) When measuring distance in statute or nautical miles, round it off to the nearest one-tenth of a mile and make sure the appropriate bar scale is used.

(5) Distance measured on a map does not take into consideration the rise and fall of the land. All distances measured by using the map and graphic scales are flat distances. Therefore, the distance measured on a map will increase when actually measured on the ground. This must be taken into consideration when navigating across country.
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Valley (Major Terrain Feature)

Valley. A valley is a stretched-out groove in the land, usually formed by streams or rivers. A valley begins with high ground on three sides, and usually has a course of running water through it. If standing in a valley, three directions offer high ground, while the fourth direction offers low ground. Depending on its size and where a person is standing, it may not be obvious that there is high ground in the third direction, but water flows from higher to lower ground. Contour lines forming a valley are either U-shaped or V-shaped. To determine the direction water is flowing, look at the contour lines. The closed end of the contour line (U or V) always points upstream or toward high ground



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Saddle (Major Terrain Feature)

Saddle. A saddle is a dip or low point between two areas of higher ground. A saddle is not necessarily the lower ground between two hilltops; it may be simply a dip or break along a level ridge crest. If you are in a saddle, there is high ground in two opposite directions and lower ground in the other two directions. A saddle is normally represented as an hourglass.



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Spur (Minor Terrain Feature)

Spur. A spur is a short, continuous sloping line of higher ground, normally jutting out from the side of a ridge. A spur is often formed by two rough parallel streams, which cut draws down the side of a ridge. The ground sloped down in three directions and up in one direction. Contour lines on a map depict a spur with the U or V pointing away from high ground.



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Ridge (Major Terrain Feature)

Ridge. A ridge is a sloping line of high ground. If you are standing on the center-line of a ridge, you will normally have low ground in three directions and high ground in one direction with varying degrees of slope. If you cross a ridge at right angles, you will climb steeply to the crest and then descend steeply to the base. When you move along the path of the ridge, depending on the geographic location, there may be either an almost unnoticeable slope or a very obvious incline. Contour lines forming a ridge tend to be U-shaped or V-shaped. The closed end of the contour line points away from high ground.



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Hill (Major Terrain Feature)

Hill. A hill is an area of high ground. From a hilltop, the ground slopes down in all directions. A hill is shown on a map by contour lines forming concentric circles. The inside of the smallest closed circle is the hilltop.



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Draw (Minor Terrain Feature)

Draw. A draw is a less developed stream course than a valley. In a draw, there is essentially no level ground and, therefore, little or no maneuver room within its confines. If you are standing in a draw, the ground slopes upward in three directions and downward in the other direction. A draw could be considered as the initial formation of a valley. The contour lines depicting a draw are U-shaped or V-shaped, pointing toward high ground.



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Depression (Major Terrain Feature)

Depression. A depression is a low point in the ground or a sinkhole. It could be described as an area of low ground surrounded by higher ground in all directions, or simply a hole in the ground. Usually only depressions that are equal to or greater than the contour interval will be shown. On maps, depressions are represented by closed contour lines that have tick marks pointing toward low ground.



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Cliff (Minor Terrain Feature)

Cliff. A cliff is a vertical or near vertical feature; it is an abrupt change of the land. When a slope is so steep that the contour lines converge into one "carrying" contour of contours, this last contour line has tick marks pointing toward low ground. Cliffs are also shown by contour lines very close together and, in some instances, touching each other.




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Handling A Compass
COMPASS HANDLING

Compasses are delicate instruments and should be cared for accordingly.

a. Inspection. A detailed inspection is required when first obtaining and using a compass. One of the most important parts to check is the floating dial, which contains the magnetic needle. The user must also make sure the sighting wire is straight, the glass and crystal parts are not broken, the numbers on the dial are readable, and most important, that the dial does not stick.

b. Effects of Metal and Electricity. Metal objects and electrical sources can affect the performance of a compass. However, nonmagnetic metals and alloys do not affect compass readings. The following separation distances are suggested to ensure proper functioning of a compass:

High-tension power lines ................................................. 55 meters.

Field gun, truck, or tank .................................................. 18 meters.

Telegraph or telephone wires and barbed wire ................ 10 meters.

Machine gun ................................................................... 2 meters.

Steel helmet or rifle .......................................................... 1/2 meter.


c. Accuracy. A compass in good working condition is very accurate. However, a compass has to be checked periodically on a known line of direction, such as a surveyed azimuth using a declination station. Compasses with more than 3° + variation should not be used.

d. Protection. If traveling with the compass unfolded, make sure the rear sight is fully folded down onto the bezel ring. This will lock the floating dial and prevent vibration, as well as protect the crystal and rear sight from damage.

USING A COMPASS

Magnetic azimuths are determined with the use of magnetic instruments, such as lensatic and M2 compasses. The techniques employed when using the lensatic compass are as follows:

a. Using the Center-hold Technique. First, open the compass to its fullest so that the cover forms a straightedge with the base. Move the lens (rear sight) to the rearmost position, allowing the dial to float freely. Next, place your thumb through the thumb loop, form a steady base with your third and fourth fingers, and extend your index finger along the side of the compass. Place the thumb of the other hand between the lens (rear sight) and the bezel ring; extend the index finger along the remaining side of the compass, and the remaining fingers around the fingers of the other hand. Pull your elbows firmly into your sides; this will place the compass between your chin and your belt. To measure an azimuth, simply turn your entire body toward the object, pointing the compass cover directly at the object. Once you are pointing at the object, look down and read the azimuth from beneath the fixed black index line. This preferred method offers the following advantages over the sighting technique:

(1) It is faster and easier to use.

(2) It can be used under all conditions of visibility.

(3) It can be used when navigating over any type of terrain.

(4) It can be used without putting down the rifle; however, the rifle must be slung well back over either shoulder.

(5) It can be used without removing eyeglasses.



Figure 9-2. Center-hold technique.

b. Using the Compass-to-Cheek Technique. Fold the cover of the compass containing the sighting wire to a vertical position; then fold the rear sight slightly forward. Look through the rear-sight slot and align the front-sight hairline with the desired object in the distance. Then glance down at the dial through the eye lens to read the azimuth.

NOTE: The compass-to-cheek technique is used almost exclusively for sighting, and it is the best technique for this purpose.



Figure 9-3. Compass-to-cheek technique.

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Cut and a Fill (Supplementary Terrain Features)

Cut. A cut is a man-made feature resulting from cutting through raised ground, usually to form a level bed for a road or railroad track. Cuts are shown on a map when they are at least 10 feet high, and they are drawn with a contour line along the cut line. This contour line extends the length of the cut and has tick marks that extend from the cut line to the roadbed, if the map scale permits this level of detail

Fill. A fill is a man-made feature resulting from filling a low area, usually to form a level bed for a road or railroad track. Fills are shown on a map when they are at least 10 feet high, and they are drawn with a contour line along the fill line. This contour line extends the length of the filled area and has tick marks that point toward lower ground. If the map scale permits, the length of the fill tick marks are drawn to scale and extend from the base line of the fill symbol



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Interpretation of Terrain Features

Terrain features do not normally stand alone. To better understand these, you need to interpret them from the map. Terrain features are interpreted by using contour lines, the SOSES approach, "ridgelining", or "streamlining".


Figure 10-26. Terrain features.

a. Contour Lines. Emphasizing the main contour lines is a technique used to interpret the terrain of an area. By studying these contour lines, you will be able to obtain a better understanding of the layout of the terrain and to decide on the best route.

(1) The following description pertains to Figure 10-27. Running east to west across the complex landmass is a ridgeline. A ridgeline is a line of high ground, usually with changes in elevation along its top and low ground on all sides. The changes in elevation are the three hilltops and two saddles along the ridgeline. From the top of each hill, there is lower ground in all directions. The saddles have lower ground in two directions and high ground in the opposite two directions. The contour lines of each saddle form half an hourglass shape. Because of the difference in size of the higher ground on the two opposite sides of a saddle, a full hourglass shape of a saddle may not be apparent.


Figure 10-27. Ridgelining and streamlining.

(2) There are four prominent ridges. A ridge is on each end of the ridgeline and two ridges extend south from the ridgeline. All of the ridges have lower ground in three directions and higher ground in one direction. The closed ends of the U's formed by the contour lines point away from higher ground.

(3) To the south lies a valley; the valley slopes downward from east to west. Note that the U of the contour line points to the east, indicating higher ground in that direction and lower ground to the west. Another look at the valley shows high ground to the north and south of the valley.

(4) Just east of the valley is a depression. There is higher ground in all directions when looking from the bottom of the depression.

(5) There are several spurs extending generally south from the ridgeline. They, like ridges, have lower ground in three directions and higher ground in one direction. Their contour line U's point away from higher ground.

(6) Between the ridges and spurs are draws. They, like valleys, have higher ground in three directions and lower ground in one direction. Their contour line U's and V's point toward higher ground.

(7) Two contour lines on the north side of the center hill are touching or almost touching. They have ticks indicating a vertical or nearly vertical slope or a cliff.

(8) The road cutting through the eastern ridge depicts cuts and fills. The breaks in the contour lines indicate cuts, and the ticks pointing away from the roadbed on each side of the road indicate fills.

b. SOSES. A recommended technique for identifying specific terrain features and then locating them on the map is to make use of five of their characteristics known by the mnemonic SOSES. Terrain features can be examined, described, and compared with each other and with corresponding map contour patterns in terms of their shapes, orientations, sizes, elevations, and slopes.

(1) Shape. The general form or outline of the feature at its base.

(2) Orientation. The general trend or direction of a feature from your viewpoint. A feature can be in line, across, or at an angle to your viewpoint.

(3) Size. The length or width of a feature horizontally across its base. For example, one terrain feature might be larger or smaller than another terrain feature.

(4) Elevation. The height of a terrain feature. This can be described either in absolute or relative terms as compared to the other features in the area. One landform may be higher, lower, deeper, or shallower than another.

(5) Slope. The type (uniform, convex, or concave) and the steepness or angle (steep or gentle) of the sides of a terrain feature.

Through practice, you can learn to identify several individual terrain features in the field and see how they vary in appearance.

NOTE: Further terrain analysis using SOSES can be learned by using the Map Interpretation and Terrain Association Course. It consists of three separate courses of instruction: basic, intermediate, and advanced. Using photographic slides of terrain and other features, basic instruction teaches how to identify basic terrain feature types on the ground and on the map. Intermediate instruction teaches elementary map interpretation and terrain association using real world scenes and map sections of the same terrain. Advanced instruction teaches advanced techniques for map interpretation and terrain association. The primary emphasis is on the concepts of map design guidelines and terrain association skills. Map design guidelines refer to the rules and practices used by cartographers in the compilation and symbolization of military topographic maps. Knowledge of the selection, classification, and symbolization of mapped features greatly enhances the user's ability to interpret map information.



c. Ridgelining. This technique helps you to visualize the overall lay of the ground within the area of interest on the map. Follow these steps:

(1) Identify on the map the crests of the ridgelines in your area of operation by identifying the close-out contours that lie along the hilltop.

(2) Trace over the crests so each ridgeline stands out clearly as one identifiable line.

(3) Go back over each of the major ridgelines and trace over the prominent ridges and spurs that come out of the ridgelines.

The usual colors used for this tracing are red or brown; however, you may use any color at hand. When you have completed the ridgelining process, you will find that the high ground on the map will stand out and that you will be able to see the relationship between the various ridgelines (Figure 10-27).

d. Streamlining. This procedure (Figure 10-27) is similar to that of ridgelining.

(1) Identify all the mapped streams in the area of operations.

(2) Trace over them to make them stand out more prominently.

(3) Then identify other low ground, such as smaller valleys or draws that feed into the major streams, and trace over them.

This brings out the drainage pattern and low ground in the area of operation on the map. The color used for this is usually blue; but again, if blue is not available, use any color at hand so long as the distinction between the ridgelines and the streamlines is clear.

"Hand" Navigation:


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Land Navigation Task - Compute Back Azimuths
Standards: Determined the back azimuth of a given azimuth to the exact degree or mils.
Conditions: Given azimuths and a requirement to compute back azimuths.

1. Determine a back azimuth using degrees. Suppose you follow a 65-degree azimuth from point A to point B and then want to go back to your original location. To do this, you use a back azimuth. You simply add 180 to the first azimuth. Your back azimuth is 65 + 180 = 245 degrees.

2. Determine a back azimuth using mils. You move from point A to point B on an azimuth of 1150 mils. Should you wish to return to point A, you would follow a back azimuth. To determine the back azimuth you simply add 3200 mils to 1150: 3200 + 1150 = 4350.


There are 360 degrees in a full circle. If you are attempting to get back to where you came from at any time, and walked along that path, you would be going 180 degrees in reverse of your previous heading. This is why you add (or subtract) 180 degrees to (or from) your azimuth.

Note. The rule to remember to determine a back azimuth is as follows:
-Degrees: Less than 180 degrees, you will add 180 degrees. More than 180 degrees, you will subtract 180 degrees.
-Mils: Less than 3200 mils, add 3200 mils. More than 3200 mils, subtract 3200 mils.

Evaluation Preparation:
Setup: Provide the soldier with azimuths, one in degrees and one in mils.

Brief Soldier: Tell the soldier to compute the exact back azimuths.

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Evaluation Guidance: Score the soldier GO if the performance measure is passed. Score the soldier NO GO if the performance measure is failed. If the soldier scores NO GO, show what was done wrong and how to do it correctly.

Source: FM 3-25.26

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woah!
Nice work @Brokor

 

Well done Brokor.....most excellent post!!!!!