Introduction to Map

Quick Start from Experience Ques 1. What is a map? Ques 2. When we need a map?

What is a map? o It is a picture or representation of the earth surface o It shows how places are related to each other by distance, direction, and size o It is a way of showing a part of the earth surface on a flat piece of paper

Other definitions of map o It is a detailed and accurate illustration of man-made and natural features on the ground such as roads, railways, power transmission lines, contours, elevations, rivers, lakes and geographical names o It is a generalized view of an area, usually some portion of earth surface, as seen from above at a greatly reduced size o It is a geographical image of the environment o It is a two-dimensional representation of the spatial distribution of selected phenomena o It is a two-dimensional representation of the earth’s three-dimensional landscape

When we need a map? o Finding a friends house in the town o Going for a walk, climbing, skiing, adventure o Going to a large city o Going to a new city (shopping, tourism) o Driving from one city to another

Why make maps? o To represent a larger area than we can see o To show a phenomenon or process we can’t see with our eyes o To present information concisely o To show spatial relationships

What information is on a map? o Relief: mountains, valleys, slopes, depressions as defined by contours o Hydrography: lakes, rivers, streams, swamps, rapids, falls o Vegetation: wooded areas o Transportation: roads, trails, railways, bridges, airports, seaports o Culture: buildings, urban development, power transmission line, pipelines, towers o Boundaries: international, provincial, administrative, recreational, geographical o Toponymy: place names, water feature names, landform names, boundary names

o A globe is a map o Globes are some of the most accurate maps that exist o Because the earth is a three- dimensional object that is close to sphere o Maps lose their accuracy because they are actually projections of a part of or the entire Earth o A globe has disadvantages that a map does not have ? o What are the disadvantages? The Globe

Disadvantages Can not show a small area for a project Difficult to carry The Globe

The oldest map was found in Mesopotamia drawn on a clay tablet that belongs to 2,500 BC Greek and the Arab geographers laid the foundation of modern cartography The earliest maps that have withstood the test of time were made on clay tablets o Maps were produced on leather, stone, and wood. The most common medium for producing maps on is, of course, paper o Today, maps are produced on computers, using software such as GIS (Geographic Information System) Evaluation of Maps

The oldest map belongs to 2,500 BC

o The way maps are made has also changed. Originally, maps were produced using land surveying, triangulation, and observation o As technology advanced, maps were made using aerial photography, and then eventually remote sensing o The appearance of maps has evolved along with their accuracy o Maps have changed from basic expressions of locations to works of art, extremely accurate, mathematically produced map Evaluation of Maps

Old Maps Babylonian clay map 2300 BCPtolemy AD Waldseemuller 1500 AD1950 AD

Scale of Maps o Scale is a ratio of the distance on the map to the distance on the ground o Scale can be expressed in fraction, descriptive, graphic representation 1:50,000 1 inch equals 10 miles

Scale of Maps o A large-scale map shows a small area such as a neighborhood street in great detail o A small-scale map shows a large area such as a country or a continent in comparatively lesser detail Small Area = Large Scale Large Area = Small Scale

Large-scale Small-scale

What is a grid? o It is a regular pattern of parallel lines intersecting at right angles and forming squares o It is used to identify precise positions. To help you locate your position accurately on the surface of the earth (or map sheet) o Maps have two kinds of referencing systems: Universal Transverse Mercator (UTM) projection (easting/northing) Geographic: degrees and minutes (longitude/latitude) Grid System

Latitude o The set of lines crossing the Earth’s surface horizontally, circling east and west o They measure degrees north and south of the equator o They are also known as parallels

Longitude o A set of lines that run vertically along earth’s surface from the North Pole to the South Pole o They measure degrees east and west of the Prime Meridian

Map Grid Reference o Eastings- these are vertical gridlines. They are called so because their values increase towards the East (Eastwards) o Northings- these are horizontal gridlines. They are called so because their values increase towards the North (Northwards) o It involves writing the value of the Easting first and then adding on the value of the Northing

Map Grid Reference o For example if the feature lies on the Easting 09 and on Northing 79 then its grid reference would be o It is important to note that grid references have six figures o But it can be of 8, 10, 16 or any figures depending on accuracy required

Dhaka ’E ’N

MIST E N

o True North: this is the direction of the North Pole from the observer. It is the line from any position on the earth’s surface to the North Pole o Magnetic North: this is the direction to which a magnetic compass needle points. This is the direction of the magnetic North Pole from any position on the earth’s surface o Grid North: this is the direction of the Eastings on a map

How can I determine where I am on a map? o Identify as many features around you as you can, man-made or natural, and locate those same features on your map o Then orient the map so that it corresponds to the ground features that you have identified; if needed, use a compass o By using a compass, take bearings to the known features and then from the known features o Plot the bearing lines o The intersection of these lines should indicate your location

Q1. How can I determine where I am on a map? o Magnetic bearing taken from your location to Tower Building, Road-bend and Mosque are 28, 120 and 330 deg respectively o Magnetic declination is 2 deg east o Find out own location at the map you have o Assumption: TN and GN same (Grid declination 0 0 ) o Show the procedure of finding out own location by free-hand sketch o Why intersection lines may not meet in one point?

How can I determine where I am on a map?

Q2. How can I determine where I am on a map? o Compass bearing 75 deg o Bearing frim map 79 deg o Magnetic declination 3 deg E o What is the grid declination? o Solution 1 deg W

Q3. How can I determine where I am on a map? o Compass bearing 330 deg o Bearing frim map 325 deg o Grid declination 1 deg E o What is the magnetic declination? o Solution 4 deg W

Why intersection lines may not meet in one point o Error in compass o Error in taking magnetic bearing o Error in map o Error in plotting bearings (bottom mid-point) o Change in natural or man-made feature

Making Maps o Maps are produced by cartographers o Cartography refers both the study of maps and the process of map-making o It has evolved from basic drawings of maps to the use of computers and other technologies to assist in making and mass producing maps

4 ways in Making a Map o Using a photo o Using an aerial photo o Using a fieldsketch o Using another map

Gathering Information o Surveying o Aerial Photography (Air Planes) o Remote Sensing (Satellites)

Problem of Distortion Features are stretched to put Earth’s information onto a map

Map Colors 5 Colors o Yellow o Green o Brown o Blue o Black o Plus the white of the paper o And a course overlay in Red or Purple

Yellow: Open Land

Green: Thicker Vegetation

Brown: Shape of the Land Contour lines represent elevation in the landscape

Blue: Water Features

Black: Man-made and Rock

White: Open Forest

Colors in the Legend

o Colors represent a variety of information on a map o Legend indicates what the colors mean Colors in Thematic map Life Expectancy Map

GPS (Global Positioning System) Satellites orbit around our earth in order to give us our precise location in the world

SATNAV (Satellite Navigation) A system of computers and satellites that tell exactly where we are or how to get to a place. Uses GPS technology

GIS (Geographic Information System) GIS is a computer system capable of capturing, storing, analyzing and displaying data which has a geographical (locational) reference. Layers of data can be stored and then analyzed.