1. OBJECTIVE
TWW compare and contrast the components of various map projections in order to evaluate the optimal use of each projection for certain tasks

2. Map Projections
Map projections  attempt to portray the surface of the earth or a portion of the earth on a flat surface
Types of distortions:
(1) conformality
(2) distance
(3) direction
(4) scale
(5) area

3. (1) Conformality
When the scale of a map at any point on the map is the same in any direction, the projection is conformal.
Meridians (lines of longitude) and parallels (lines of latitude) intersect at right angles.
Shape is preserved locally on conformal maps

4. United States – 3 Ways

5. North America – 2 Ways

6. 4 Categories of Map Projections
(1) Cylindrical Projections
(2) Conic Projections
(3) Azimuthal Projections
(4) Miscellaneous Projections

7. (1) Cylindrical Map Projections
When the cylinder is tangent to the sphere contact is along a great circle (the circle formed on the surface of the Earth by a plane passing through the center of the Earth)

8. Other means of Cylindrical Projection

9. Cylindrical  (1) Cylindrical Equal Area
straight meridians and parallels
the meridians are equally spaced
the parallels unequally spaced.
Scale is true along the equator
Scale is true along two lines equidistant from the equator
Shape and scale distortions increase near points 90 degrees from the equator

10. Cylindrical  (1) Cylindrical Equal Area

11. Cylindrical  (2) Mercator Projection
straight meridians and parallels that intersect at right angles.
Scale is true at the equator or at two standard parallels equidistant from the equator
often used for marine navigation because all straight lines on the map are lines of constant azimuth… constant direction

12. Cylindrical  (2) Mercator Projection

13. Cylindrical  (3) Mollweide Projection
used for world maps
The central meridian is straight. The 90th meridians are circular arcs.
Parallels are straight, but unequally spaced.
Scale is true only along the standard parallels of 40:44 N and 40:44 S

14. Cylindrical  (3) Mollweide Projection

15. Cylindrical  (4) Robinson
Used by National Geographic
based on tables of coordinates, not mathematical formulas
distorts shape, area, scale, and distance in an attempt to balance the errors of projection properties
Allows for slight distortion in all areas to not have extreme distortion in one.

16. Cylindrical  (4) Robinson

17. (2) Conic Projections projecting a spherical surface onto a cone.
(a) tangent to the sphere contact is along a small circle
(b) the cone touches the sphere along two lines, one a great circle, the other a small circle.

18. Conic Examples  Albers Equal Area
distorts scale and distance except along standard parallels
Areas are proportional and directions are true in limited areas.
Used in the United States and other large countries with a larger east-west than north-south extent.

19. (3) Azimuthal (Planar) Projection
result from projecting a spherical surface onto a plane.
the plane is tangent to the sphere contact is at a single point on the surface of the Earth

20. Azimuthal  (1) Polar Projection
Distances measured from the center are true.
Distortion of other properties increases away from the center point.

21. Azimuthal  (2) Orthographic
used for perspective views of hemispheres
Area and shape are distorted.
Distances are true along the equator and other parallel

22. (4) Miscellaneous Projections  Goode’s Projection
Cut and paste … interrupts the oceans and Australia and New Zealand farther west than reality. Minimized distortion in shape of land masses

23. (4) Miscellaneous Projections  Dymaxion map
depicts the earth's continents as "one island," or nearly contiguous land masses.
The arrangement heavily interrupts the map in order to preserve shapes and sizes.

24. Matching Practice Activity to Best Choice of Projection
___ 1. Mollweide ___ 2. Robinson ___ 3. Dymaxion ___ 4. Albers Equal Area ___ 5. Mercator
Anthropologist of equatorial countries
Shipping captain visiting only the major ports of the world
Editor of a geographic magazine
Trip planner for a presidential candidate
A scientist attempting to prove the idea of Pangaea

25. Matching  Activity to Best Choice of Projection
__A 1. Mollweide __C 2. Robinson __E 3. Dymaxion __D 4. Albers Equal Area __B 5. Mercator
Anthropologist of equatorial countries
Shipping captain visiting only the major ports of the world
Editor of a geographic magazine
Trip planner for a presidential candidate
A scientist attempting to prove the idea of Pangaea

26. IGNORE THE NEXT SLIDE!

27. Develop Your Own Situations
Azimuthal/Polar Projection
Goode’s Projection
Orthographic
Albers Equal Area