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2240A/B (14)
Lecture

Geography 2240A/B Lecture Notes - Times New Roman, Main Source, Corel

, Winter 2014
14 pages79 viewsWinter

Department
Geography
Course Code
Geography 2240A/B
Professor
P.J.Stooke

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Lecture 1
Objectives
1. How to produce maps
To illustrate reports and papers
2. How maps are made
To help understand them (e.g. more skeptical about contours after you have drawn some)
To understand their possibilities and limitations
3. Some basic computer graphic skills
Background for other courses in remote sensing, GIS
Preparation of web graphics
Cartography
-Definition:
oThe art and science of making maps
-Art:
oDesign:
Aesthetics – For an attractive map
Functionality – For a useful map
oCreativity
Cartographers have to follow certain conventions
But there is still room for individuality, creativity
-Science:
oSurveying – Accurate measurement of location
oData collection – Contents of the map
oPerception – How we extract information from a map
-History of cartography:
oA major area of study itself
Maps
-Definition:
o“…graphic representations that facilitate a spatial understanding of things, concepts, conditions,
processes or events…”
o(from Harley, J.B. and Woodward, D., The History of Cartography, Vol. 1)
oMany textbooks give inadequate definitions, biased towards modern geographic maps
-Plans and charts:
oNo different from maps
oPlan – Usually refers to a map of a small object like a building, room or even a machine
oChart – Usually refers to a map used for navigation
oBut they are both just types of map. The distinction is arbitrary and unnecessary
Coordinates
Location On The Earth
-Coordinate reference points:
oEarth is nearly spherical (within 0.5%)
oAssume it is a perfect sphere
oEarth rotates around its axis of rotation
oMain reference line for coordinates
oMeets surface at north and south poles

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oEquator defined by plan perpendicular to axis, passing through the planet’s centre
-Latitude
oAngular distance north or south from equator to poles
oGeocentric Latitude – Angle between the equatorial plane and radius (centre of Earth to a point)
oGeographic Latitude – Angle between the equatorial plane and vertical line at a point
-Longitude
oMeasured east or west from a meridian (line from pole to pole)
oInternational convention: Prime meridian runs through the Greenwich Observatory in London,
England
oMeasured 180 degrees to East and West (rarely: 360 degrees around the globe, east from the prime
meridian)
oTwo angles, latitude N or S of the equator and longitude E or W from the prime meridian, define a
position on the globe
Location On A Map
-Latitude and longitude:
oGrid drawn on map or marked along the edges
oE.g. A point is at 45 degrees, 50 minutes 22 seconds north, and 78 degrees, 20 minutes, 10 seconds
west
oWritten as: 45° 50’ 22” N, 78° 20’ 10” W
oCheck out this link for more information:
http://www-istp.gsfc.nasa.gov/stargaze/Slatlong.htm
-Universal Transverse Mercator (UTM) grid (military grid)
oUniversal – Covers the whole world
oTransverse Mercator – Map projection it is based on
oSquare grid, 1km spacing
oDrawn in long narrow strips (zones) – Total of 60 zones
oEach zone covers 80° N to 80° S, only 6° of longitude wide
oPoles mapped separately with a grid centred on the pole
oCheck out this link for more information:
http://geology.isu.edu/geostac/Field_Exercise/topomaps/utm.htm
-Grid reference:
oLike stating x-y coordinates on a graph
oEdges of map are labelled like axes of a graph
oGive Easting – Distance in east-west direction, estimated to a tenth of a grid square (100m for a
1km grid)
oGive Northing – Distance north-south estimated to 1/10 square
Example: 43.7 easting, 55.3 northing, written as 427553
oBut note that this is an abbreviated grid reference, just used for convenience. 100km north or east of
here would be another place with the same numbers. The full reference avoids this – see link below.
A full grid reference tells us which zone we are in and gives unambiguous coordinates, as in the
linked example
oCheck this link for more information:
http://maps.nrcan.gc.ca/topo101/utm_references_e.php
-Arbitrary grid of letters or numbers
oCommon on street maps
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Lecture 2
Map Scale, Directions
Scale
-Precise geometric relationship between a map and the region it portrays
oOne of the most important characteristics of a modern map
oMost maps are greatly reduced in size compared to their subjects, so scale is a small fraction
-Definition:
oRatio of the size of the map to its subject
oScale = Distance on a map / distance on the ground
-Example:
oTwo points on the ground are 1000m apart
oRepresented on the map by points only 1cm apart
oCalculate scale as follows:
1cm represents 1000m
1000m = 100,000cm
So 1cm represents 100,000cm
So scale = 1cm / 100,000cm = 1/100,000
-Scale is a fraction expressed in 3 ways:
oRepresentative Fraction (RF) – E.g. 1 : 100,000
oVerbal Scale – ‘One cm represents one km’
oGraphic ScaleA line labeled with the distance it represents
-Graphic scale remains accurate if map is enlarged or reduced. Verbal ad RF scales do not
-On a graphic scale, the intervals must be convenient round numbers
Scale Examples
-Example: Ground distance = 5 km, map distance = 2 cm
oStep 1: 2 cm represents 5 km (write in full)
oStep 2: 1 cm represents 2.5 km (divide so left side = 1)
oStep 3: 1 cm represents 250,000 cm (convert to same units)
oStep 4: Scale is 1: 250,000 (express as a representative fraction)
-Example: Distance on map = 3.5 cm, map scale = 1: 15,000
oWhat is the real distance?
oStep 1: 1 cm represents 15,000 cm (express scale in words, same units as your measurement)
oStep 2: 3.5 cm represents (3.5 x 15,000) cm = 52500 cm (multiple both sides by map distance)
oStep 3: 3.5 cm represents 525 m (convert to more convenient units)
oAnswer: 525 m
Scale
-Large and small scales:
oScale is a fraction
o½ is larger than ¼
o1/5000 is larger than 1/100,000
o1: 5000 is a larger scale than 1: 100,000
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