map reading iv determining direction grc jrotc col(r) alexander

Map Reading IVDetermining Direction

GRC JROTC

COL(R) Alexander

Outline

• Purpose

• Polar Coordinates & Practical Exercise

• Intersection & Practical Exercise

• Resection & Practical Exercise

• Summary

• Conclusion

Polar Coordinates1. Plot an azimuth from a known point.

– EG 1290 8018

2. Plot the distance from the known point along the azimuth line.

• 56 degrees

3. The Polar Coordinate is at the end of the azimuth/distance line.

• 3400 M

Tenino Map

STEP 1: PLACE THE INDEX MARK OF THE PROTRACTOR AT THE CENTER OF MASS ON THE POINT FROM WHICH YOU ARE MEASURING.

POINT 1EG 1290 8018

Tenino Map

ENSURE your protractor is

straight UP & DOWN !

STEP 2: LOCATE THE DESIRED AZIMUTH ON THE PROTRACTOR SCALE AND PLACE A DOT ON THE MAP AT THIS AZIMUTH.

PNT 1

56EXAMPLE: 56 DEGREES EXAMPLE: 56 DEGREES

STEP 3: REMOVE THE PROTRACTOR AND CONNECT THE POINT AND DOT WITH A STRAIGHT LINE.

PNT 1

STEP 3. REMOVE THE PROTRACTOR AND CONNECT THE POINT AND DOT WITH A STRAIGHT LINE.

PNT 1PNT 1

STEP 3: REMOVE THE PROTRACTOR AND CONNECT THE POINT AND DOT WITH A STRAIGHT LINE.

56o

STEP 4: SELECT THE APPROPRIATE SCALE MEASUREMENT AND PLACE A PAPER STRAIGHT EDGE ON THE SCALE.

Piece of white paper

EXAMPLE: DISTANCE IN METERS

STEP 5: DETERMINE THE DESIRED DISTANCE TO MEASURE FROM THE SCALE AND MARK THE PAPER AT THIS DISTANCE USING TICK MARKS.

EXAMPLE: 3400 METERS (3000 + 400)

3400 M

100 100 100 100 100 100

Each alternating block is 100 Meters

STEP 6: ALIGN THE STRAIGHT EDGE WITH THE AZIMUTH LINE. ENSURE THE FIRST TICK MARK IS CENTER MAST ON THE KNOWN POINT.

PNT 1

3400 Meters

STEP 4: PLACE A DOT ON THE MAP AT THE SECOND TICK MARK FROM THE STRAIGHT EDGE ON THE MAP.

PNT 1

THE POSITION OF THE SECOND TICK MARK IS THE POSITON OF THE UNKNOWN POINT.

_____ _____ _____ _____ _____ _____ _____ _____

GRID SQUARE

USE Protractor !

1 3 5 5 8 8 5 5

PNT 1

REMOVE THE STRAIGHT EDGE AND DETERMINE THE GRIDCOORDINATE TO THE SECOND POINT.

Read the Grid:

EG 1575 8205 3400 M

56o

1. QUESTION: What are the polar coordinates plotted from the center of the Reservoir at EG 04609945 at a grid azimuth of 158 degrees and a distance of 1700 meters? Describe this location?• EG 0525 9790 (road intersection next to a Pit)

2. QUESTION: What are the polar coordinates plotted from the water tower in grid square EG1185 at a grid azimuth of 30 degrees and a distance of 3500 meters? Describe the terrain feature located here?

• EG 1325 8860 (spur)

3. QUESTION: What are the polar coordinates plotted from the Deschutes fire tower in grid square EG 1795 at a grid azimuth of 303 degrees and a distance of 2600 meters? Describe the terrain feature located here?

• EG 1550 9660 (saddle)

Practical Exercise (ANSWERS)

Intersection(determining the location of an object/point)

1. Determine the position (GRID LOCATION) of an

unknown point (or object) by occupying at least two

(2), but preferably three (3) known locations.

2. Determine the azimuth (magnetic-compass) to the

unknown point from these locations

3. Plot the azimuths (grid-map) from the positions to

locate the to the unknown point by their intersections

on the map.

STEP 1: SIGHT THE UNKNOWN POINT (or OBJECT) ON THE GROUND.

STEP 2: LOCATE YOUR POSITION ON THE GROUND AND MARK IT ON THE MAP.

POS 1

You must be able to accurately locate (a GRID)

your POSITION !

STEP 2. LOCATE YOUR POSITION ON THE GROUND AND MARK IT ON THE MAP.

EXAMPLE: ROAD JUCTION AT EG13508009

POS 1

You must be able to accurately locate your

POSITION !

POS 1

STEP 3. DETERMINE THE MAGNETIC AZIMUTH FROM THE ROAD JUNCTION TO THE ENEMY POSITION (with a COMPASS).

59 DEGREES

MAGNETIC

POS 1

BUT WAIT ! WHAT DO YOU HAVE TO DO WITH THAT

COMPASS AZIMUTH BEFORE YOU CAN USE IT ON A MAPMAP?

59 DEGREES

MAGNETIC

MAGNETIC AZIMUTH: 59 DEGREES

EASTERLY G-M ANGLE: +21 DEGREES

GRID AZIMUTH: 80 DEGREES

STEP 4: CONVERT THE MAGNETIC AZIMUTH TO A GRID (map) AZIMUTHGRID (map) AZIMUTH.

Tenino Map

STEP 5: DRAW A LINE FROM THE ROAD JUNCTION ALONG THE 80 DEGREE GRID AZIMUTH.

POS 1

80

POS 2

POS 1

STEP 6: MOVE TO (or contact someone else who can provide a magnetic azimuth) A SECOND POSITION WHERE THE UNKNOWN POINT/OBJECT CAN BE SEEN AND OBTAIN ANOTHER COMPASS AZIMUTH TO THE OBJECT AND MARK THE AZIMUTH ON THE MAP.

POS 1

STEP 6: MOVE TO (or contact someone else who can provide a magnetic azimuth) A SECOND POSITION WHERE THE UNKNOWN POINT/OBJECT CAN BE SEEN AND OBTAIN ANOTHER COMPASS AZIMUTH TO THE OBJECT AND MARK THE AZIMUTH ON THE MAP..

EXAMPLE: ROAD JUCTION AT EG13318108

POS 2

POS 2

POS 1

79 DEGREESMAGNETIC

STEP 7: DETERMINE THE MAGNETIC AZIMUTH FROM THE SECOND ROAD JUNCTION TO THE OBJECT / POSITION.

POS 2

POS 1

79 DEGREESMAGNETIC

BUT WAIT ! WHAT DO YOU HAVE TO DO WITH THAT

COMPASS AZIMUTH BEFORE YOU CAN USE IT ON A MAPMAP?

MAGNETIC AZIMUTH: 79 DEGREES

EASTERLY G-M ANGLE: +21 DEGREES

GRID AZIMUTH: 100 DEGREES

STEP 4: CONVERT THE MAGNETIC AZIMUTH TO A GRID AZIMUTHGRID AZIMUTH.

POS 1

POS 2100

STEP 9. DRAW A LINE FROM THE SECOND ROAD JUNCTION ALONG THE 100 DEGREE GRID AZIMUTH.

POS 1

POS 2

STEP 10: WHERE THE LINES CROSS IS THE LOCATION OF THE UNKNOWN POINT or OBJECT (enemy tank).

EG16208055

POS 1

POS 2

IT’S DESIRABLE TO REPEAT THE PROCEDURE FROM A THIRD POINT TO INCREASE THE ACCURACY.

MAGNETIC AZIMUTH: 128 DEGREESEASTERLY G-M ANGLE: +21 DEGREES

GRID AZIMUTH: 149 DEGREES

EXAMPLE: ROAD JUNCTION AT EG15478180

POS 3

MAGNETIC AZIMUTH: 128 DEGREESEASTERLY G-M ANGLE: +21 DEGREES

POS 1

POS 2

POS 3

NOTICE THAT THE LINES FROM THE FIRST AND SECONDPOINT FORM A SHALLOW ANGLE.

THIS DECREASES ACCURACY. WHENEVER POSSIBLE, CHOOSE LOCATIONS THAT WILL GIVE YOU A LARGER ANGLE (CLOSER TO 90 DEGREES LIKE POSITION 3.)

NOTE: WHEN TRIANGULATING, THE CENTER OF THE TRIANGLE IS RECORDED AS THE LOCATION.

EG16208055

YOUR SQUAD OCCUPIES 2 OBSERVATION POSTS. THE TEAM AT THE WATER TOWER IN GRID SQUARE EG 0985 SEES THE ENEMY AT A MAGNETIC AZIMUTH OF 351 DEGREES. THE SECOND TEAM, LOCATED AT THE WATER TOWER IN GRID SQUARE EG 1185 SEES THE ENEMY AT A MAGNETIC AZIMUTH OF 300 DEGREES.

QUESTION: WHAT IS THE GRID LOCATION OF THE ENEMY?

ANSWER: GRID COORDINATE EG 0979 8765

Practical Exercise1 of 2

YOUR SQUAD IS OPERATING AS AN OBSERVATION TEAM & YOUSEE SIX (6) ENEMY HELICOPTERS LAND & THEN DISAPPEAR FROM YOUR SIGHT. PRIOR TO THE HELICOPTERS DISAPPEARING, YOU SHOT A MAGNETIC AZIMUTH TO THE LOCATION WHERE YOU SAW THEM LAND. THIS MAGNETIC AZIMUTH IS 316 1/2 DEGREES. YOUR LOCATION IS THE BRIDGE IN GRID SQUARE EH 1000. YOU CONTACT YOUR OTHER TEAM LOCATED IN THE ZION CHAPEL TOWER AT GRID SQUARE EH 1102. THEY HAVE A SIGHTING OF SIX (6) ENEMY HELICOPTERS AT A MAGNETIC AZIMUTH OF 229 1/2 DEGREES. BOTH YOUR TEAMS PERFORM AN INTERSECTON.

QUESTION: WHAT IS THE GRID LOCATION AND THE TYPE OF TERRAIN WHERE THE SIX (6) ENEMY HELICOPTERS LANDED?

ANSWER: GRID LOCATION EH 093022, DEPRESSION.

Practical Exercise2 of 2

Resection (determining YOUR location using known objects/points)

1. Determine the position of an unknown point (YOU)

by locating at least two (2), but preferably three (3)

known locations (points on the ground).

2. Determine the azimuth to the known points from

the unknown point/location.

3. Plot the back azimuths from the known points to

locate the unknown point by their intersections.

EXAMPLE: TOWER LOCATED AT EG 1804 8759

STEP 1: LOCATE A FEATURE OR OBJECT THAT IS IDENTIFIABLE ON BOTH THE GROUND AND THE MAP AND MARK THE MAP LOCATION.

“Where in the heck am I???”

KP 1

STEP 1: LOCATE A FEATURE OR OBJECT THAT IS IDENTIFIABLE ON BOTH THE GROUND AND THE MAP AND MARK THE MAP LOCATION.

EXAMPLE: TOWER LOCATED AT EG 1804 8759

29 DEGREES

MAG

NETIC

STEP 2: MEASURE THE MAGNETIC AZIMUTH (w/ your COMPASS) TO THE KNOWN POSITION (Tower) AND CONVERT THE MAGNETIC AZIMUTH TO A GRID AZIMUTH.

MAGNETIC AZIMUTH: 29 DEGREES

EASTERLY G-M ANGLE: +21 DEGREES

GRID AZIMUTH: 50 DEGREES

STEP 2: MEASURE THE MAGNETIC AZIMUTH TO THE KNOWN POSITION AND CONVERT THE MAGNETIC AZIMUTH TO A GRID AZIMUTH.

GRID AZIMUTH: 50 DEGREES

ADD: +180 DEGREES

GRID BACK AZIMUTH: 230 DEGREES

STEP 3. CHANGE THE GRID AZIMUTH TO A BACK AZIMUTH & DRAW A LINE FROM THE KNOWN POSITION (Tower) BACKWARD TOWARD YOUR UNKNOWN POSITION.

STEP 3: CHANGE THE GRID AZIMUTH TO A BACK AZIMUTH & DRAW A LINE FROM THE KNOWN POSITION (Tower) BACKWARD TOWARD YOUR UNKNOWN POSITION.

230

KP 1

EXAMPLE: BRIDGE LOCATED AT EG 1500 8389

STEP 4: LOCATE A SECOND FEATURE OR OBJECT THAT IS IDENTIFIABLE ON BOTH THE GROUND & THE MAP AND MARK THE MAP LOCATION.

STEP 4: LOCATE A SECOND FEATURE OR OBJECT THAT IS IDENTIFIABLE ON BOTH THE GROUND & THE MAP AND MARK THE MAP LOCATION.

EXAMPLE: BRIDGE LOCATED AT EG 1500 8389

KP 1

KP 2

151 DEGREES

MAGNETIC

STEP 5: MEASURE THE MAGNETIC AZIMUTH (w/ your Compass) TO THE SECOND KNOWN POSITION & CONVERT THE MAGNETIC AZIMUTH TO A GRID AZIMUTH.

MAGNETIC AZIMUTH: 151 DEGREES

EASTERLY G-M ANGLE: +21 DEGREES

GRID AZIMUTH: 172 DEGREES

STEP 5: MEASURE THE MAGNETIC AZIMUTH TO THE SECOND KNOWN POSITION & CONVERT THE MAGNETIC AZIMUTH TO A GRID AZIMUTH.

GRID AZIMUTH: 172 DEGREES

ADD: 180 DEGREES

GRID BACK AZIMUTH: 352 DEGREES

STEP 6: CHANGE THE GRID AZIMUTH TO A BACK AZIMUTH & DRAW A LINE FROM THE SECOND KNOWN POSITION BACKWARD TOWARD YOUR UNKNOWN POSITION.

STEP 6. CHANGE THE GRID AZIMUTH TO A BACK AZIMUTH AND DRAW A LINE FROM THE SECOND KNOWN POSITION BACKWARD TOWARD YOUR UNKNOWN POSITION.

352

KP 1

KP 2

EG 1485 8494

STEP 7: THE POINT WHERE THE 2 LINES INTERSECT IS YOUR LOCATION.

KP 1

KP 2

STEP 8: FOR A CHECK ON ACCURACY, YOU SHOULD CONSTRUCT A THIRD LINE FOLLOWING THE STEPS AS OUTLINED.

KP 1

KP 2

KP 3

WHENEVER POSSIBLE, CHOOSE LOCATIONS THAT WILL GIVE YOU A LARGER ANGLE WHERE THE LINES INTERSECT TO INCREASE ACCURACY.

WHILE ON A RECONNAISSANCE MISSION, AN ENEMY SCOUT PLATOON DETECTS YOUR SQUAD. YOU TAKE UP A DEFENSIVE POSITION & DECIDE TO REQUEST INDIRECT FIRE SUPPORT. YOU ARE NOT SURE OF YOUR LOCTION. FROM YOUR LOCATION, YOU CAN SEE A LOOKOUT TOWER IN GRID EG 1887 AT A MAGNETIC AZIMUTH OF 110 DEGREES & A TV RELAY TOWER IN GRID EG1287 AT A MAGNETIC AZIMUTH OF 215 DEGREES.

QUESTION: WHAT IS YOUR LOCATION?

ANSWER: EG 155 897

YOU DETERMINE A DISTANCE OF 800 METERS TO THE ENEMY WITH YOUR LASER RANGE FINDER AND A MAGNETIC AZIMUTH OF 290 DEGREES.

QUESTION: WHAT IS THE GRID LOCATION OF THE ENEMY SCOUT PLATOON?

ANSWER: EG 149 902

Practical Exercise1 of 2

QUESTION: YOU HAVE DETERMINED THAT THE MAGNETIC AZIMUTH FROM YOUR POSITION TO THE TV RELAY TOWER IN GRID SQUARE EG1287 IS 3 DEGREES & THE MAGNETIC AZIMUTH TO THE SPOT ELEVATION 199 IN GRID SQUARE EG 1385 IS 77 DEGREES. WHAT IS THE SIX DIGIT GRID COORDINATE OF YOUR LOCATION?

ANSWER: EG 116856

QUESTION: THE MAGNETIC AZIMUTH FROM YOUR LOCATION TO THE WATER TOWER AT EG093853 IS 63 DEGREES AND THE MAGNETIC AZIMUTH TO THE WATER TOWER AT EG097827 IS 104 DEGREES. WHAT IS THE SIX DIGIT COORDINATE TO YOUR LOCATION?

ANSWER: EG 063849

Practical Exercise2 of 2

Summary

• Purpose

• Polar Coordinates & Practical Exercise

• Intersection & Practical Exercise

• Resection & Practical Exercise

• Summary

• Conclusion

Conclusion

Advanced land navigations techniques such as polar coordinates, intersection, and resection are essential to navigating successfully and accurately. Having theses skills will help you fight, survive, and win on the battlefield.