|
|
|
The study of contour lines to determine high and low points of elevation is usually adequate for military operations. However, there may be a few times when we need a quick and precise reference to determine exact elevations of specific points. When exactness is demanded, a profile is required. A profile, within the scope and purpose of this manual, is an exaggerated side view of a portion of the earth's surface along a line between two or more points.
a. A profile can be used for many purposes. The primary purpose is to determine if line of sight is available. Line of sight is used—
(1) To determine defilade positions.
(2) To plot hidden areas or dead space.
(3) To determine potential direct fire weapon positions.
(4) To determine potential locations for defensive positions.
(5) To conduct preliminary planning in locating roads, pipelines, railroads, or other construction projects.
b. A profile can be constructed from any contoured map. Its construction requires the following steps:
(1) Draw a line on the map from where the profile is to begin to where it is to end (Figure 10-28).
Figure 10-28. Connecting points.
(2) Find the value of the highest and lowest contour lines that cross or touch the profile line. Add one contour value above the highest and one below the lowest to take care of hills and valleys.
(3) Select a piece of lined notebook paper with as many lines as was determined in (2) above. The standard Army green pocket notebook or any other paper with 1/4-inch lines is ideal. Wider lines, up to 5/8-inch, may be used. If lined paper is not available, draw equally spaced horizontal lines on a blank sheet of paper.
(4) Number the top line with the highest value and the bottom line with the lowest value as determined in (2) above.
(5) Number the rest of the lines in sequence, starting with the second line from the top. The lines will be numbered in accordance with the contour interval (Figure 10-29).
Figure 10-29. Dropping perpendiculars.
(6) Place the paper on the map with the lines next to and parallel to the profile line (Figure 10-29).
(7) From every point on the profile line where a contour line, stream, intermittent stream, or other body of water crosses or touches, drop a perpendicular line to the line having the same value. Place a tick mark where the perpendicular line crosses the number line (Figure 10-29). Where trees are present, add the height of the trees to the contour line and place a tick mark there. Assume the height of the trees to be 50 feet or 15 meters where dark green tint is shown on the map. Vegetation height may be adjusted up or down when operations in the area have provided known tree heights.
(8) After all perpendicular lines have been drawn and tick marks placed where the lines cross, connect all tick marks with a smooth, natural curve to form a horizontal view or profile of the terrain along the profile line (Figure 10-29).
| NOTE: |
The profile drawn may be exaggerated. The spacing between the lines drawn on the sheet of paper determines the amount of exaggeration and may be varied to suit any purpose. |
(9) Draw a straight line from the start point to the end point on the profile. If the straight line intersects the curved profile, line of sight to the end point is not available (Figure 10-30).
Figure 10-30. Drawing lines to additional points.
(10) Determine the line of sight to other points along the profile line by drawing a line from the start point to additional points. In Figure 10-31, line of sight is available to—
| A—Yes |
D—Yes |
G—Yes |
| B—No |
E—No |
H—No |
| C—No |
F—No |
I—No |
Figure 10-31. Drawing a hasty profile.
The vertical distance between navigable ground up to the line of sight line is the depth of defilade.
c. When time is short, or when a complete profile is not needed, one may be constructed showing only the hilltops, ridges, and if desired, the valleys. This is called a hasty profile. It is constructed in the same manner as a full profile (Figure 10-31).
Return to Elevation and Relief
|
|
 
|
|
|
The Long Walk by Slavomir Rawicz
In 1941, the author and a small group of fellow prisoners escaped a Soviet labor
camp. Their march out of Siberia, through China, the Gobi Desert, Tibet, and over
the Himalayas to British India is a remarkable statement about man's desire to be
free. Buy it at Amazon.com
|
|
| |
Books
Buy the book this website is based on: Map Reading and
Land Navigation
This website is based on the US Army Field Manual: "Map Reading and Land Navigation"
Buy a copy from Amazon.com to take with you out in the field.
|
| |
One of the best ways to learn and become proficient in any subject is to find a way to make a game or sport of it. That's exactly what orienteering does! Orienteering began to develop almost 100 years ago in the Scandinavian countries as a fun and effective method for military training in land navigation. Bjorn Kjellstrom was closely involved with the early development of orienteering, and he is the person who introduced the sport to North America. He, along with his brother Alvar, and a friend named Gunnar Tillander, invented the modern orienteering compass. They manufactured and marketed it as the Silva Protractor compass. This compass, along with Bjorn's book Be Expert with
Map and Compass, made it much easier for anyone to learn how to use a map and compass.
This book has become the most widely read classic on the subject of map reading, compass use, and orienteering. Over 500,000 copies have been sold in the english language editions alone. There have been very successful editions published in French, Italian, and other languages as well. It is a short (just over 200 pages), easy to read, enjoyable book that can help you to have fun while you learn the subject quickly and effectively.
The book is organized into four main parts, plus a short, useful introduction. Part 1 covers having fun with maps alone. Then, Part 2 covers having fun with a compass alone. Part 3 puts it together and shows you how to have fun with a map and compass together. This section also introduces the game or sport of orienteering. Part 4 covers competitive orienteering for those who would like to compete with others in the sport.
A reproduction of a segment of an actual topographic map is included as a fold-out in the back of the book. It is used together with the "how-to" instructions the book provides. For example, one of the exercises in Part 3 is an imaginary orienteering "hike" that uses the sample map.
If you would like to have one of the best books available on map reading and using a compass,
Be Expert with
Map and Compass is hard to beat. You can buy a copy from Amazon.com today.
|
|
|
|
|
|
1. HOME