Transcript MAPS, PROJECTIONS, TOOLS Unit 1- Introducing Basic Concepts

Unit 1- Introducing Basic Concepts
MAPS, PROJECTIONS, TOOLS
Maps
 Geography’s most
important tool for thinking
spatially about the
distribution of features
across Earth is a map
 Definition:
 A two-dimensional or flatscale model of Earth’s
surface
 Science of mapmaking
called cartography
 A map serves two
purposes:
 Reference tool
 Communications tool
History of the Map
 Earliest Maps were reference
 Exploration Age
tools
 Cartography revived during
 Designed to show a traveler how
Age of Exploration thanks to
Columbus, Magellan, and other
explorers
 Between 1470-1520 1st map
with “America” labeled appears
to get from Point A to Point B
 Important Names
 Eratosthenes
 Coined the word “geography”
 Determined circumference of the
world
 Ptolemy
 Produced maps used for over
1000 years
 Aristotle
 Determined Earth was spherical
Contemporary Mapping
 Uses
 Describe data
 Sources of data
 Tools for analysis
 Example:
 Hurricane Katrina
 Representations of the
world
 Usually two-dimensional
graphic representations that
use lines and symbols to convey
information or ideas about
spatial relationships
Types of Maps
 Topographic Maps
 Designed to represent
Earth’s surface and to
show permanent features
such as buildings,
highways, field
boundaries, and political
boundaries
 Device for representing the
form of Earth’s surface is the
contour
 A line that connects points of
equal distance above or below
a zero data point, usually sea
level
Types of Maps
 Reference Maps
 Show common features such as
boundaries, roads, and
mountains
 Thematic Maps
 Designed to represent the
spatial dimensions of particular
conditions, processes, or events
 Types of Thematic Maps
 Isopleth maps
 Maps based on isolines
 A line that connects places of
equal data value
 Dot maps
 Single dot or other symbol
represents a specified number
of occurrences of some
particular phenomenon or
event
 Choropleth map
 Tonal shadings are graduated
to reflect variations in
numbers, frequencies, or
densities
CHOROPLETH MAP
 Map Scale:
 refers to the relationship of
a feature’s size on a map to
its actual size on earth
 Ratio between linear
distance on a map and
linear distance on Earth’s
surface
 Usually expressed in terms
of corresponding lengths:
 as in one centimeter equals
one kilometer
 Or as a representative
fraction
 Small scale maps= bigger
fraction
 Large scale maps = smaller
fraction
Scale Differences: Maps of Florida
The effects of scale in maps of Florida. (Scales from 1:10 million to 1:10,000)
Types of Scale
 Fractional
 shows the numerical ratio
between distances on the
map on earth’s surface
 example: 1:24,000
 Means 1 map unit= 24, 000
units on ground
 Graphic
 consists of a bar line
marked to show distance
on the earth’s surface
 example:
Written
 relationship between the
map and earth distances in
words
 example: 1 inch equals 1 mile
 1st number represents map’s
distance
 2nd number represents earth’s
distance
 What scale you use
depends on what
information you are
portraying
talking map
Projection

Definition:


the scientific method of
transferring locations on the
earth’s surface to a flat map
earth’s surface is curved and
not a perfect sphere. It is
impossible to represent on a
flat plane without distortion

Four problems:




the shape of an area can be
distorted
the distance between two
points may increase or
decrease
the relative size of different
areas may be altered so that
one area may appear larger
the direction from one place
to another can be distorted.
the Solution?????
 Different types of
projections
Equidistant Projections




can represent distance
accurately in only one direction
(usually north-south)
usually provide accurate scale
in perpendicular direction
most aesthetically pleasing
Conformal Projections


Projection on which compass
directions are rendered
accurately
Types of Map Projections:
 Equal-Area:
 Relative sizes of the landmasses
on the map are the same as in
reality
 Minimizes distortion
 Fuller:
 maintains accurate size and
shape
 completely rearranges direction
 Robinson:
 Shape is distorted little
 Useful for displaying oceans
 Disadvantage = land areas are
much smaller
 Direction is consistent
 distorts all 4 but minimizes
 Mercator:
errors in each (most balanced)
 Map is rectangular
 Distorts area
 higher latitudes distorted Greenland appears huge!
 Azimuthal:

puts N or S pole at center of
map
 view of looking up or down at earth
Mercator Projection
The world’s 24 standard time zones are often depicted using the Mercator projection.
Different Projections
 Peters
 Deliberate attempt to give
prominence to
underdeveloped countries
of equatorial regions and
the Southern Hemisphere
 Adopted by United Nations
 Shape gives “shock value”
 Cartogram
 Space is transformed
according to statistical
factors
 Largest mapping units
represent greatest statistical
values
Geographic Grid
 Definition:
 System of imaginary arcs drawn
in a grid pattern on Earth’s surface
 The location of any place on
Earth’s surface can be
described precisely by
meridians and parallels
 Meridian
 An arc drawn between the North
and South poles
 Location of each meridian =
longitude
 Measured from the Prime Meridian
(0-180 degrees East or West)
 Greenwich, England
 Parallel
 A circle drawn around the globe
parallel to the equator and at
right angles to the meridians
 Location of each parallel=
Latitude
 Measured from the Equator
(0-90 degrees North or South)
Basic Tools and Methods of Human
Geographers
 Observation
 Information must be collected
and data recorded
 Methods:
 Fieldwork
 Use of scientific instruments
 Laboratory experiments
 Archival searches
 Remote sensing
 Aerial photography or
satellite imagery designed to
record data on visible,
infrared, and microwave
sensor systems
 Visualization or Representation
Written descriptions
 Charts
 Diagrams
 Tables
 Analysis
 Heart of geographic research
 Objective analysis is to discover
patterns and establish
relationships so that hypotheses
can be established and models be
built
Remote Sensing
 Remote Sensing
 acquisition of data
about earth’s surface
from satellite images
that are transmitted in
digital form.
 Remote-Sensing satellites
scan the Earth’s surface
 Geographers use remote
sensing to map the
changing distribution of
a wide variety of
features such as:
 Agriculture, drought, and
sprawl
 Example
 used with Hurricane Katrina to
monitor areas of impact
Global Positioning System (GPS)
 Definition:
 System that accurately
determines the precise location of
something on Earth
 GPS in the United States
includes three elements:
 GPS devices enable private
individuals to contribute to the
production of accurate digital
maps
 Travelers can upload information
about streets, buildings, etc. to
improve maps in the future
 Satellites placed in
predetermined orbits by the U.S.
military
 24 in operation, 3 in reserve
 Tracking stations to monitor and
control the satellites
 A reciever that can locate at least
4 satellites to pinpoint locations
 GPS is most commonly used
for navigation
 Can also be used for fieldwork for
history, geography, etc.
Geographic Information System (GIS)
 Definition:
 a computer system that can
capture, story, query, analyze,
and display geographic data.
 Produces maps that are more
accurate and attractive than
hand-drawn maps
 The position of any object
on Earth can be measured
and stored in a computer
 A map can be created by
retrieving a number of stored
objects and combining them to
form an image
 Each type of information is
stored in a layer
 Layers can be compared t0
show relationships among
different kinds of information
Layers of a GIS
•
Each layer represents a different category of information.
Geographical Information Systems
 GIS technology can render
visible many aspects of
geography there were
previously unseen
 Images that could never be drawn
by hand
 GIS can put places under the
microscope, creating detailed
new insights using huge
databases
 Military applications
 Allows infantry commanders to
calculate line of sight from tans
and defensive emplacements
 Allows cruise missiles to fly
below enemy radar
 GIS allows an enormous range
of problems to be addressed
 Geodemographic research
 Uses census and commercial data
about the populations of small
districts in creating profiles for
market research