Transcript Introduction to Mapping

Introduction to Mapping
Map Projections
Fun with Fruit
1. Identify and mark on the fruit the locations
of the North Pole and South Pole.
2. Locate the spot that is halfway between the
two poles and use a marker to draw a line
around the Earth at that point, which
geographers refer to as the equator.
3. Draw a few lines of longitude on the map.
(left to right)
Draw shapes to
represent the continents
on Earth.
Draw shapes to represent the
continents on Earth.
Use a knife to pierce the skin of the fruit,
then use your fingers to get under the
skin to peel it off the fruit. Try to keep as
much of the "globe" intact as possible.
Now, create a map that is flat and readable
and compare it to another group
Maps have been used for over 4500 years for
exploring, determining location and direction
of travel, and for describing the shape of the
world.
When the features of a globe are transferred
onto a flat surface, a map projection is
created. There are hundreds of different
ways to do this, therefore there are
hundreds of different projections.
Map Problem #1
• The Earth is a round like object called a “Geoid”
• It is not perfectly round
• To simplify we use a Sphere or Ellipsoid to
represent the shape of the earth
Map Problem #2
• Maps are Flat and the Earth is not!
• Fruit Example
– The peels when laid flat on the table began to rip
– Maps have to compensate for the “rips” that
occur when we take a round object and try to
show it on a flat surface
Map Problem #3
•
To compensate for rips one of four things
happens:
1.
2.
3.
4.
The Size of features on a map will be distorted
The Shape of features will be distorted
Directions will be distorted
Distances will be distorted
• Most map projections are created on
computers using complex mathematical
equations. Each projection has characteristics
that make it useful for different purposes, and
each has its own advantages/disadvantages.
These disadvantages are called distortions.
– Remember: WHAT YOU SEE IN A MAP IS NOT, AND
CANNOT BE, A TRUE REPRESENTATION OF THE
EARTH.
What to do?
• Cartographers will use different maps for
different purposes.
– Sometimes they will distort shape if size is more
important and vice-versa
• The projection they use will determine what
is distorted and by how much
What is a Map Projection?
• Picture a globe with a bulb in the middle.
• The bulb shines light onto paper touching the
globe
• The land makes a shadow on the paper and it is
then traced
The Light can come from different
Angles!!!
Where to Put the Paper?
•
There are three common Map Projections
1. Conical
•
•
•
•
Good for the middle of the earth
Makes the polar regions smaller
Equatorial regions bigger
Shape is kept for the most part
#2 Planar or Azmithul
• Putting a flat piece of paper
that either touches or “cuts
through” the globe
• Mostly used for polar
regions but can be used
anywhere
• Distance is only true from
the centre outwards
• Only accurate where the
plane touches
# 3 Cylindrical
• This is used for world Maps
• The equatorial region or lower
latitude regions will have little
distortion, but the polar regions are
enlarged quite significantly
• Most common and famous:
Mercator Projection
Azmithul Example of Canada
The Mercator Projection
• Used for sailing
• Shows straight
lines between
places
Mercator Projection
+
-
Gives true
compass
bearings
between points
(good for
navigation)
Greatly distorts
the size of land
masses
(countries near
the equator
appear smaller)
Canada as a Mercator Projection
Winkel Tripel –
1998, National Geographic decided
to address the problem of distortion
on world maps. This projection
provides the best balance between
size, shape, distance, and direction. It
give a more realistic representation
of the earth
Some other examples of World
Maps
Goode's Homolosine Equal-area Projection
Eckert IV Equal-area World
Map Projection
Sinusoidal Equal-area World
Map Projection
Discuss
• What are some of the advantages of using
globes rather than using maps?
• What are some of the advantages of using
maps rather than using globes?
• What are some reasons we may use maps?
(camping/hiking/canoeing/etc…)
Try the shaded area on pg 19
Homework
1. Create a title page for Mapping
2. 1D-pg 26 # 1-3,6-8,10
1P-pg26 #1,2,6,11