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--- guides:land_nav [2017/04/21 16:25]
thendash added bearing and intersection sections
+++ guides:land_nav [2017/11/22 14:57]
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-~~Title: Land Navigation~~
-===== LAND NAVIGATION(WIP) =====
-By: Thendash
-==== PREFACE ====
-'Land Navigation' aims to instruct members on performing basic land navigation duties. The author of this document does not recommend that a
-reader attempt to use the techniques described henceforth in real life situations and as such you do so at your own risk.
-==== SCOPE ====
-This guide contains information on map reading and land navigation techniques, primarily as they pertain to ArmA.
-===== MAP READING =====
-==== INTRODUCTION ====
-Maps provide information on the existence, location of, and the distance between ground features. It also indicates variations in terrain,
-heights of natural features, and the extent of vegetation cover. They will be your primary tool in use during land navigation and therefore
-you must be familiar with all aspects of a map and how to read them.
-==== TYPE ====
-The map used in ARMA 3 is a variable scale, topographic map using a simplified MGRS(Military Grid Reference System). Compared to real life
-maps, the ARMA map differs in a few ways, primarily:
-  - No difference between magnetic North and true North.
-  - No magnetic declination to account for.
-  - No grid zone designator to account for.
-==== SYMBOLS AND MARGINAL INFORMATION ====
-**Margin**
-The only marginal information on the ARMA 3 map, is scale and contour line distance.
-**Symbols**
-{{ :guides:legend-for-arma-3-map.gif?direct&300|Click to view full size}}
-Because it is often not practical to show certain objects at scale on a map, or because more information than just the shape and size of
-an object is required, symbols are commonly displayed on the map.
-Common symbols seen on the ARMA map are categorized into two categories, **man made objects** and **natural objects**.
-Symbols representing **man made objects** include:
-  - Primary Paved Roads(MSR)
-  - Paved Roads(ASR)
-  - Dirt Roads
-  - Foot Paths
-  - Town and City Centers
-  - Buildings and Walls
-  - Prominent Vertical Structures(Antenna, Wind Generator, Lighthouse, etc)
-  - Runways and Airports
-Symbols representing **natural objects** include:
-  - Contour and Elevation
-  - Mountain Peaks
-  - Water Features
-  - Forested Areas
-  - Brush
-==== GRIDS ====
-Reading a grid reference is essential to locating and communicating positions in the world onto a map.
-**Precision**
-The map is divided into equally sized grid squares, and the intersecting lines are numbered both vertically(Eastings) and
-horizontally(Northings). Each digit of a grid reference represents one decimal place, starting at 10 km with the two digit grid reference.
-  - **10 km** square: **2 digit** reference
-  - **1 km** square: **4 digit** reference
-  - **100 m** square: **6 digit** reference
-  - **10 m** square: **8 digit** reference
-  - **1 m** square: **10 digit** reference
-**Reading a grid**
-{{ :guides:gridref.png?direct&300|Click to view full size}}
-It is easy to read 2, 4, and 6 digit grid references from the ARMA map because the map scales as you zoom in and out, but you can read a
-more precise grid reference using either map tools or estimation. Either way, the steps remain the same:
-  - Read **LEFT TO RIGHT** first
-  - Read **BOTTOM TO TOP** second
-  - Combine the two readings together to create the grid reference.
-These steps can be remembered by the mnemonic, **‘RIGHT in the house, UP the stairs’**
-==== ELEVATION ====
-**Contour Lines**
-Elevation on the map is represented by contour lines. ARMA uses two types of contour lines:
-  - **Index Lines:** Starting at sea level, every fifth contour line is considered an Index Line and is shown in red on the map.
-  - **Intermediate Lines:** All contour lines between the index lines are considered intermediate lines and are spaced at the current contour interval.
-**Contour Interval**
-You can find the ‘contour interval’ in the bottom right margin on the ARMA map. The contour interval represents the vertical distance
-between any two adjacent contour lines at the current map scale. Thus, the closer the contour lines are grouped, the steeper the slope is
-because more vertical distance is covered in a shorter horizontal distance.
-Contour lines never intersect because any point on a contour line is at the same elevation above or below sea level.
-===== EQUIPMENT =====
-==== COMPASS ====
-{{ :guides:compass.png?direct&300|Click to view full size}}
-The compass is a tool used to measure direction. The version modeled in ARMA is a lensatic compass with both degree and milliradian
-markings.
-**Measuring Direction**
-Typically we measure direction either generally using the cardinal directions, or more precise using degrees. Mils are not often used in
-ARMA.
-  - **Cardinal Direction:** The four cardinal directions are displayed on the center of the compass ring and allow for quick reference of general direction.
-  - **Bearing Degrees:** The inner ring of the compass shows degrees printed every ten degrees and a hash mark every five degrees. There are 360 degrees.
-  - **Bearing Mils:** The outer ring of the compass shows mils printed every 200 mils, large hash mark every 100 mils, and a small hash mark every 20 mils. There are 6400 mils.
-==== MAP TOOLS ====
-The ACE3 MapTool is currently broken.
-==== DAGR ====
-===== NAVIGATION TECHNIQUES =====
-==== BEARING ====
-Technically //azimuth// is the proper term, but the term //bearing// is commonly used to refer to the direction to an object or location
-in relation to magnetic North.
-In ARMA we do not need to worry about the difference between magnetic bearings measured with a compass, and grid bearings measured on the
-map.
-**Taking a Bearing**
-To measure a bearing from your current location to a visible object:
-  - Line up the //sighting wire// on your compass with the object
-  - Read the bearing in degrees where the //index line// intersects with the //inner ring.//
-**Back Bearing**
-A back bearing is the opposite direction of a bearing. It is commonly required for use during land navigation.
-To convert a bearing into a back bearing:
-  * **Add 180 degrees** if the bearing is **180 degrees or less**
-  * **Subtract 180 degrees** if the bearing is **180 degrees or greater**
-==== LOCATION ====
-**INTERSECTION**
-{{ :guides:intersection.png?direct&300|Click to view full size}}
-Intersection is the location of an unknown point by successively occupying at least two known positions on the ground and then map
-sighting on the unknown location. It is not often used in ARMA, but can be used to locate the position of an otherwise inaccessible location.
-**Steps:**
-  - Measure the direction to the target from known location 1.
-  - Draw the bearing from known location 1.
-  - Move, or communicate with someone at a different known location.
-  - Measure the direction to the target from known location 2.
-  - Draw the bearing from the known location 2.
-  - (Optional)Repeat from subsequent known locations as desired.
-  - The **intersection** of the drawn bearings is the location of the target.