Presentation on theme: "The Science and Art of Map Making"— Presentation transcript:
1The Science and Art of Map Making CARTOGRAPHYThe Science and Art of Map Making
2SOMEBASICSA map is a two-dimensional or flat-scale model of the earth’s surface.Cartography is the science AND ART of mapmakingMap Scale is the relationship between the size of a feature on a map and the size of that same feature on the earthScale is often represented in ratio/fraction, written or graphic (bar graph) formWhen comparing map scales, a small scale map means that a very big section of the earth is shown (above, top) and a large scale map means that a little area is show (above, bottom)
8EARLY MAPMAKING ARISTOTLE ERATOSTHENES FEI XIU AL-IDRISI Earth’s shadow is circularMatter falls to centerStars move with travelEarth is sphericalFirst coined “geography”Found earth’s circumferencePrepared earliest map of world with five principleclimate regionsProduced detailed map of China in 267 BCEWorld map and geography text in 1154 CEIbn-Battutah wrote a travelogue spanning 75,000 miles and 30 year
9AGE OF EXPLORATIONColumbusMagellanDe GamaEuropean geographic studies had died during the middle ages.It began to revive again towards the Renaissance.Europeans rediscovered Ptolemy’s maps and writings.Cartographers took explorer’s information to make better maps.17th Century maps displayed accurate outlines of most continents and oceans.
10TYPES OF MAPS Maps display information by location. Cartographers choose the type of information they want to choose and they way they want to display it.General maps (like road maps) display a variety of information.THEMATIC MAPS are designed to show a particular theme (type of information) that is associated with certain areas.Thematic maps can display physical, social, political, cultural, sociological, economic, agricultural, etc. aspects of a region.The above map displays shipping lanes in blue and the time it takes to deliver packages to various regions in shades of brown to yellow.
11US Cell Phone Tower Locations DOTDISTRIBUTIONUSES:Shows exact location of the chosen themeShows distribution (concentration or dispersion) of the themeShows patternsOften used to show number by location (population of a theme) at local scaleWEAKNESSES:Poor differentiation in areas of high concentrationUS Cell Phone Tower Locations
12CHOROPLETH MAPS USES WEAKNESSES Shows various classification levels of a chosen themeShows theme at regional (not local) levelCompares regions in terms of chosen themeLow number of classes causes distortionHigh number of classes causes confusionCauses induction due to regional emphasis
14ISOLINE MAPS USES WEAKNESSES Isoline maps attempt to show environmental factors that have height (ex: altitude) or that have increases and decreases in a measurable value (ex: temperature, barometric pressure). Each line on the map represents the intersection of the maps surface with a horizontal plane representing a thematic value (altitude, temperature, etc) at that point. The lines allow the reader to infer slope. ANY COLOR IS SIMPLY TO PROVIDE CONTRAST FOR CLARITY.USESWEAKNESSESConnects points of equality with a chosen themeGood for displaying measured values (usually environmental factors)Temperature, elevation (relief), rain totals, weather patterns, etc.Difficult to differentiate in areas of high concentrationLow number of classes causes inductionHigh number of classes causes confusion
15Topographic Map ISOLINE MAPS HISTORY USES A topographic map (Topo) is a cross between a general map and an isoline map.They’ve been in existence since the 1600’s.THE United States Geological Survey (USGS) is responsible for making topos in the US.There are over 54,000 topo maps covering the entire US.Typical scale is 1:24,000 inches.USESUsed to show both the human and the physical landscape.Various symbols denote the human landscape.Various colors, symbols and lines represent the physical landcape.Isolines are used to show elevation (relief) of the land.
16GRADUATED SYMBOL MAP USES WEAKNESSES Shows amount (volume, size, number, etc. by class)Shows location (local, regional, etc.)Allows for comparisonOverlapping symbols cause confusionSymbolization can trigger bias
17MODERNCARTOGRAPHYOnce a cartographer decides on the scale of his map (large scale or small scale) , he has to make some hard choices: what to leave out, how represent thematic data, and how many classes of data to represent.These decisions will make maps inherently inaccurate since they will not show the world as it really is.Maps can be inaccurate in four ways:SIMPLIFICATIONINDUCTIONCATEGORIZATIONSYMBOLIZATION
18SIMPLIFICATIONSimplification occurs when a map omits details that aren’t relevant to the purpose of the map… roads, terrain features, etc.Simplification can also mean that curved roads get straightened and two points that are far apart get closer together.Check out the simplification in this map from the Dallas Airport to then site of a wedding.
19INDUCTIONInduction is a phenomenon associated ONLY with choropleth map.A choropleth map shades a region a certain color that corresponds to the dominant trait in that region. Even though not all of the people in the region display that trait, the map makes it appear as if everyone does.On choropleth maps, the minority is inducted into the majority trait.Consider the below maps of the 2004 presidential election.The first awards counties to the majority vote-getter.The second awards states to the majority of counties.The third awards the country to the majority electorate.Consider how induction works at each level.
20CATEGORIZATION Categorization also occurs only with chorolpleth maps. When a cartographer chooses the maps theme (population density by state on the maps below) he chooses not only the number of classes to display, but also the dividing lines of the classes. The choice can radically alter the viewers perception and opinion.According to each map, where do people live?Map 1?Map 2?Map 3?
21SYMBOLIZATIONSymbolization occurs with basic and graduated symbol maps.The cartographer chooses the symbols that will represent various map features, and those symbols can distort the viewer’s opinions and perceptions.The map at left uses red dots to symbolize cholera victims. How would your perceptions change if he had chosen a skull and crossbones? A daisy?
22Reality: Earth is a sphere PROJECTIONS Earth is a nearly perfect sphere, and a globe is an accurate, scale model of it.THE PROBLEMSA useful globe would be too large to manageA globe can’t fold for easy transportationA globe is too large to fit you your pocket, glovebox, etc.
23The Solution: Make the world flat PROJECTIONS A projection is a method for taking the 3D earth and transferring its image onto a 2D (flat) surface.THE PROBLEMSA sphere is hard to flatten.The process of making the flat surface DISTORTS size, distance and direction on the flat map.
24DISTORTION PROJECTIONS All projections cause distortion: SHAPE (more elongated or squat)DISTANCE (between two objects increases or decreases)RELATIVE SIZE (looks larger or smaller than it is)DIRECTION (not accurate between two places)
26DISTORTION SIZE Which is bigger, the US or Greenland? PROJECTIONS TOTAL LAND AREA (ACTUAL)SIZEGREENLAND2,166,086#12 in the worldUS9,826,675 sq km#3 in the world
27HOW FAR IS IT FROM SOUTH AMERICA TO AFRICA? PROJECTIONSDISTORTIONDISTANCEHOW FAR IS IT FROM SOUTH AMERICA TO AFRICA?
28Equal Area Projections TYPESEqual Area ProjectionsPROSCONSRelative size of landmasses is the same as in realityMost shapes are not distorted, but areas towards the north and south poles become distortedTo preserve size and shape, map must interrupt eastern and western hemispheresMeridians do not converge on the map and do not form right angles with the parallels
29Mercator Projections PROS CONS PROJECTION TYPES Very little shape distortionDirection is consistentMap is a nice, neat rectangleArea towards poles is grossly distorted (larger)
30Robinson Projections PROJECTION TYPES PROS CONS Visually pleasing Good for displaying information across oceansDoes not preserve area or directionsMajor distortion at poles and edgesLand area is small and limited for displaying information
31MODERN MAPTECHNOLOGYThere are a number of tools that cartographers use to gather data to display on maps. Some methods are decidedly more high tech, and others are more traditional.
32High Tech Methods MODERN MAP TECHNOLOGY High Tech methods tend to rely on computers in some way, shape or form.Rather than by hand, cartographers use computers both to gather data and to create maps.
33Global Positioning System (GPS) Remote Sensing MODERN MAPTECHNOLOGYGlobal Positioning System (GPS)Geographic Information System (GIS)Remote Sensing
34Going Old School MODERN MAP TECHNOLOGY It’s important to remember the less high tech, more first person methods of gathering map data:Census: a complete, official enumeration of a population’s characteristicsPolls and surveys: scientific questioning of a portion of the population used to determine larger trendsField observation: taking data by hand by observing it on location