cartography – plotting the world
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Cartography Fundamentals, GIS and Mapping, How to create good maps, training moduleTRANSCRIPT
Cartography – Plotting the world
The foremost cartographers of the land have prepared this for you; it’s a map of the area that you’ll be traversing
Dr. Nishant Sinha
Spatial is Special
“Everything is related to everything else, but near things are more related than distant things” Tobler, W. 1970. A computer movie simulating urban growth in the Detroit region. Economic Geography 46, 234–40.
Sometimes called the First Law of Geography (because it is generally true!).
Capturing Details
The creativity to potray
Cartography – amalgam of art, science and technology
▪ The art, science and technology of making maps
▪ Help to produce and analyze maps to enable communication of ideas
▪ Basic principles of map making– Has a clear motive or goal– Is directed toward an audience– Uses appropriate design
elements to clearly convey its message
Cartography dynamics – An example
▪ Phone call Cartography
Cartography – a communication bridge
The geographic environment Compile Recognize
Select Classify
Simplify Symbolize
Read Analyze
Interpret
Imagine
Map
Map user
Map
MapMap
CartographerReality
Reality?
Cartographic elements
▪ Maps show how different features are related
▪ All maps, however, share the same common elements– Title– Legend– Scale– Directional Indicator– Inset Maps– Projection System
Beauty is NOT the MAIN objective
The Elements of a Map: Title
▪ Most important element of the map for acquiring information efficiently is the title
▪ Identifies the map area and the type of map
▪ Cartographers may list the title simply or artistically
▪ Typically appear at the top of the map, but not always
Map of Indiana Showing Its History, Points of Interest,1967, GRMC, Ball State University Libraries
The Elements of a Map: Legend
▪ Another important feature on a map is the legend or map key
▪ Contains information needed to read a map
▪ Most maps use symbols or colors to represent different geographic features, the meaning of which is determined by legend
This legend simply identifies the roads of Texas, but the cartographer chose to be creative in the design of the legend to add character to the map. (Texas Guide Map, 194-, GRMC, Ball State University Libraries).
The Elements of a Map: Scale
▪ Almost all maps have scales
▪ Scales compare a distance measured on the map to the actual distance on the surface of the earth.
▪ Scales appear on maps in several forms, but most cartographers draw a line scale as a point of reference
This scale from a historical map of Kentucky features an image of George Washington surveying the land. (Kentucky: The Dark and Bloody Ground, An Historical and Geographical Map of the State of Kentucky, 1933, GRMC, Ball State University Libraries).
The Elements of a Map: Directional Indicator
▪ A directional indicator on a map helps determine the orientation of the map.
▪ Some cartographers place an arrow that points to the North Pole on the map. This is a “north arrow.”
▪ Other maps indicate direction by using a “compass rose,” with arrows pointing to all four cardinal directions
Ancient cartographers drew elaborate, artistic directional indicators—most commonly a compass rose. (Floridae Americae Provinciae: Recens & Exactissima Descriptio, 1564, engraved reproduction, GRMC, Ball State University Libraries).
The Elements of a Map: Inset Map
▪ Some maps feature inset maps - smaller maps on the same sheet of paper.
▪ Provide additional information not shown on the larger map
▪ Drawn at a larger, more readable scale
▪ Usually feature areas of interest related to the larger map
The larger map above is a modern map of the Nile Valley. The inset map shows the ancient Egyptian Empire in the same area.(National Geographic The Nile Valley: Land of the Pharaohs, 1963, GRMC, Ball State University Libraries).
▪ Earth is round and maps are flat, getting information from a curved surface to a flat one involves a mathematical formula called a map projection , or simply a projection
▪ This process of flattening the earth will cause distortions in one or more of the following spatial properties and No projection can preserve all these properties:
– Distance – Area – Shape – Direction
▪ Type of projections based on different types of distortion– EQUIVALENCY Correct representation of area– CONFORMALITY Correct representation of shapes– EQUIDISTANCY Correct representation of distance– AZIMUTHALCY Correct representation of direction
▪ Type of projections according to the projection surface– CONIC– CYLINDRICAL– PLANAR
In simple terms where the ‘paper touches the Earth’ there are no distortions. But the further the ‘paper’ is away from the surface of the Earth the greater distortions. The mathematics in different projections attempt to overcome this problem – but none remove all distortions.
The Elements of a Map: Map Projections
GeoidEllipsoid
Sphere
Sea Level
Height
Figure 2.4 Elevat ions defined with reference to a sphere, el lipsoid, geoid, or local sea level wil l al lbe different. Even location as lati tude and longitude will vary somewhat. When linking field datasuch as GPS with a GIS, the user must know what base to use.
Terrain
Earth Models and Datums
Standard parallels
Geographic Coordinates
Parallels
Equator
Pri
me
Mer
idia
n
Pri
me
Mer
idia
n
Mer
idia
ns
Type of projections according to the projection surface
Standard parallel
CentralMeridian
Polar Equatorial
Oblique
No flat map can be both equivalent and conformal.
The Datum
▪ An ellipsoid gives the base elevation for mapping, called a datum.
▪ Examples are NAD27 and NAD83 Everest
▪ The geoid is a figure that adjusts the best ellipsoid and the variation of gravity locally.
▪ It is the most accurate, and is used more in geodesy than GIS and cartography.
Geographic Coordinates as Data
Equivalency
▪ Also known as Equal area Projection, that preserves the area of displayed features
▪ Shape, distance and angles are distorted
▪ The meridians and parallels may not intersect at right angles but they are marked in such a way that the area represented in each quadrangle is same with the adjacent one
▪ Shapes of the features are generally distorted for a larger area
▪ in smaller areas it is difficult to visualize unless it is measured
Example: Albers Equal-Area Conic projection
Conformality
▪ Also known as Conformal Projection, which preserves the local shape
▪ To preserve the individual angles describing the spatial relationship this projection must show the perpendicular graticules intersecting at right angles
▪ Issue - Shapes of the larger areas cannot be preserved
▪ Used for smaller regions i.e. for large-scale maps
▪ Useful for navigational charts and weather maps
Example: Mercator projections
Equidistancy
▪ Also known as Equidistant Projection, which preserves the distance between two points
▪ Scale is not maintained correctly throughout an entire map
▪ There are one or two lines on a map along which the scale is maintained correctly irrespective of the fact that whether they are great or small circles and straight or curved
Example:
Azimuthalcy
▪ Also known as True direction Projection
▪ Preserves or maintains some of the great circle arcs, giving the directions or azimuths of all points on the map correctly with respect to the center
Example: Azimuthal Equidistant projections
Conic Projections
▪ Based on the concept of the ‘piece of paper’ being rolled into a cone shape and touching the Earth on a circular line
– Tip of the cone is positioned over a Pole
– Line of latitude where the cone touches the Earth is called a Standard Parallel
▪ Used for regional/national maps of mid-latitude areas – such as Australia and the United States of America.
▪ Characteristics– Fan shaped when used to map large
areas
– Have distortions increasing away from the central circular line (the ’touch point of the paper‘)
– Have very small distortions along the central circular line (the ’touch point of the paper‘)
– Shapes are shown correctly, but size is distorted
– Usually have lines of longitude fanning out from each other and have lines of latitude as equally spaced open concentric circles
This is a typical example of a world map based on the Conic Projection technique. This map is centred on central Australia and the Standard Parallel is 25° South. Note how the shapes of land masses near the Standard Parallel are fairly close to the true shape when viewed from space – see the images at the beginning of this section. This includes Australia, South America and the ’tip‘ of Africa. Also note how land masses furthest away from the Standard Parallel are very distorted when compared to the views from space. Particularly note how massively large northern Canada and the Arctic icecaps look.
Cylindrical Projections
▪ Based on the concept of the ‘piece of paper’ being rolled into a cylinder and touching the Earth on a circular line
– Cylinder is usually positioned over the Equator, but this is not essential
▪ Usually used for world maps or regional/national maps of Equatorial areas – such as Papua New Guinea
▪ Characteristics– Rectangular or oval shaped – but this
projection technique is very variable in its shape
– Have lines of longitude and latitude at right-angles to each other
– Have distortions increasing away from the central circular line (the ‘touch point of the paper’)
– Have very small distortions along the central circular line (the ‘touch point of the paper’)
– Show shapes correctly, but size is distorted..
his is an example of a cylindrical map projection and it is one of the most famous projections ever developed. It was created by a Flemish cartographer and geographer – Geradus Mercator in 1569. It is famous because it was used for centuries for marine navigation. The sole reason for this is that any line drawn on the map was a true direction. However, shapes and distances were distorted. Notice the huge distortions in the Arctic and Antarctic regions, but the reasonable representation of landmasses out to about 50° north and south.
Planar Projections
▪ Based on the ‘flat piece of paper’ touching the Earth at a point. The point is usually a Pole, but this is not essential
– Cylinder is usually positioned over the Equator, but this is not essential
▪ Also known as Azimuthal or Zenithal Projection
▪ Characteristics– Have distortions increasing away
from the central point
– Have very small distortions near the centre point (the ’touch point of the paper‘)
– Compass direction is only correct from the centre point to another feature – not between other features
– Not usually used near the Equator, because other projections better represent the features in this area
When the centre of the map is the North or South Pole maps produced using Azimuthal Projections techniques have lines of longitude fanning out from the centre and lines of latitude as concentric circles. These projections are often called polar projections.
What are my cartographic objectives?
Why?Map objectives
Convey information
Illustrate analysis results
Highlight spatial relationships
Easier comprehension of complex events
How? Design objectives Fulfill map objectives
Assign meaningful symbology
Ensure truthful depiction of reality
Fulfill communication objectives
What are my communication objectives?
PopulationSoils
Focused informationImportance can varySymbols can dominate
Variety of informationEqual importanceSubtle symbology
General mapGeneral map
Thematic mapThematic map
Qualitative Quantitative
▪ More than 3000
▪ No perfect projection
▪ All have distortions
Cylindrical
Conical
AzimuthalDirection
Distance
Shape
Area
What projection should I chose?
Displace?Displace?
Aggregate?Aggregate?Omit?Omit?
Simplify?Simplify?
Collapse?Collapse?
Typify?Typify?
Exaggerate?Exaggerate?Classify?Classify?Refine?Refine?
CE
B
C2C3 E1B1
E5C5
B4
How much detail should I include?
Color
Shape
Texture/Pattern
Gray tone value
Size
Qualitative
Quantitative
What symbols should I use?
What colors should I use?
▪ Connotations
▪ Conventions
▪ Preferences
▪ For screen or paper
R G B Y
100 70 40 10%
20 30 50 85%
Hue
Value
Saturation
Dimensions
12 colors
Maximum
7- 8 shades
What are the eye limitations?
What about the color impaired?
▪ Avoid pure green / red
▪ Vary shapes, textures
▪ Use brightness contrast (not more colors)
Normal eye
Red defective
Green defective
Blue defective
How do I represent names on my map?
▪ Legibility issues– Text color vs background color
– Uppercase vs lowercase
– No fancy fonts
RiverRIVERRiver
FormTigris
Orlando Color
BaghdadBasra
Style
Qualitative
San DiegoRedlands
SizeRedlandsSan Diego
ValueTigris
Orlando Color
RiverRIVERRiver
Form
Quantitative
• Readability issues
MakramvilleJackville1 2
How do I label names?
How do I place names at POINTS?
Mississippi Mississippi• Ambiguity issues
How do I place names at LINES?
90
80
100
90100
80
• Faster reading issues
How do I label contours?
0 3 ft
Are these dog houses? Must be visually easy to read
Correct? Easy to use?
?
What about my scale?
Objective Map form
Quantity of information
Easy / Complex
Quality
Authenticity
Symbol size, color
Reality
Audience
Conditions of use
Technical limits
Scale
Generalization
What factors control my design?
MapALWAYS
THINK of
the??
?
USERUSER
Some of the world’s Best Maps
Map of ‘Pangea’ with Current International Borders
Map by eatrio.net via Reddit
Pangea was a supercontinent that existed during the late Paleozoic and early Mesozoic eras, forming about 300 million years ago. It began to break apart around 200 million years ago. The single global ocean which surrounded Pangaea is
accordingly named Panthalassa.
Some of the world’s Best Maps
31. Earth’s Population by Latitude and Longitude
Photograph by mrgeng on Reddit
Where 2% of Australia’s Population Lives
Map by e8odie on Reddit
Some of the world’s Best Maps
Reversed Map with Southern Hemisphere at Top of Map (because position of North is arbitrary)
Map via nnm.me
Some of the world’s Best Maps
World Map Tattoo with Countries Visited Coloured
Countries That Do Not Use the Metric System
Map via Wikimedia Commons
Some of the world’s Best Maps
The Only 22 Countries in the World Britain Has Not Invaded (not shown: Sao Tome and Principe)
Map by Stuart Laycock (via The Telegraph)
Some of the world’s Best Maps
Where Google Street View is Available
Map by Google
Some of the world’s Best Maps
Global Internet Usage Based on Time of Day
Map by Carna Botnet via Reddit
Some of the world’s Best Maps
Visualizing Global Population Density
Map by valeriepieris on Reddit
Shown you tools to use- Thanks a ton!
Acknowledgement
These slides are aggregations for better understanding of GIS. I acknowledge the contribution of all the authors and photographers from where I tried to accumulate the info and used for better presentation.
Author’s Coordinates:Dr. Nishant SinhaPitney Bowes Software, [email protected]