Map projectionsMap projections

By: Ms. A. McFaddenBy: Ms. A. McFadden

Azimuthal/Polar projectionsAzimuthal/Polar projectionsAzimuthal equidistant projections are sometimes used Azimuthal equidistant projections are sometimes used to show air-route distances. Distances measured from to show air-route distances. Distances measured from

the center are true. Distortion of other properties the center are true. Distortion of other properties

increases away from the center point .increases away from the center point . Maps are Maps are circular.circular.

Cylindical ProjectionsCylindical ProjectionsBoth meridians and parallels appear as straight lines. Both meridians and parallels appear as straight lines.

But, since meridians converge at the poles there is large But, since meridians converge at the poles there is large distortion in shape and scale the closer you get to 90 distortion in shape and scale the closer you get to 90

degrees north or south. Maps are rectangular.degrees north or south. Maps are rectangular.

The Peters projection is a cylindrical equal-The Peters projection is a cylindrical equal-area projection that de-emphasizes area area projection that de-emphasizes area

exaggerations in high latitudes by shifting the exaggerations in high latitudes by shifting the

standard parallels to 45 or 47 degrees.standard parallels to 45 or 47 degrees.

The Mercator projection has straight The Mercator projection has straight meridians and parallels that intersect at right meridians and parallels that intersect at right angles. Scale is true at the equator or at two angles. Scale is true at the equator or at two

standard parallels equidistant from the standard parallels equidistant from the equator. The projection is often used for equator. The projection is often used for

marine navigation because all straight lines marine navigation because all straight lines on the map are lines of constant azimuth on the map are lines of constant azimuth

(true to their bearing).(true to their bearing).

The Robinson projection is based on tables of The Robinson projection is based on tables of coordinates, not mathematical formulas. The coordinates, not mathematical formulas. The

projection distorts shape, area, scale, and projection distorts shape, area, scale, and distance in an attempt to balance the errors distance in an attempt to balance the errors

of projection properties.of projection properties.

The Mollweide projection, used for The Mollweide projection, used for world maps, is pseudocylindrical and world maps, is pseudocylindrical and equal-area. The central meridian is equal-area. The central meridian is

straight. The 90th meridians are straight. The 90th meridians are circular arcs. Parallels are straight, circular arcs. Parallels are straight,

but unequally spaced. but unequally spaced.

Sinusoidal equal-area maps have straight Sinusoidal equal-area maps have straight parallels at right angles to a central meridian. parallels at right angles to a central meridian. Other meridians are sinusoidal curves. Scale is Other meridians are sinusoidal curves. Scale is

true only on the central meridian and the true only on the central meridian and the parallels. Often used in countries with a larger parallels. Often used in countries with a larger

north-south than east-west extentnorth-south than east-west extent

Conical projectionsConical projectionsA conic projection distorts scale and distance except A conic projection distorts scale and distance except along standard parallels. Areas are proportional and along standard parallels. Areas are proportional and

directions are true in limited areas. Used in countries directions are true in limited areas. Used in countries

with a larger east-west than north-south extentwith a larger east-west than north-south extent

Maps are fan shaped. Used for a lot for maps of Maps are fan shaped. Used for a lot for maps of

North America.North America.

Orthographic projections are used for Orthographic projections are used for perspective views of hemispheres. Area and perspective views of hemispheres. Area and

shape are distorted. Distances are true along shape are distorted. Distances are true along

the equator and other parallels.the equator and other parallels.

Perspectives from other Perspectives from other parts of the world:parts of the world:

George Bush’s ViewGeorge Bush’s View

Taking a “world view “ is about

being open-minded and

understanding other

perspectives and viewpoints on

issues that impact us as

human beings. Citizens of the

planet work towards

development that is based

on sustainability.

Are you a global citizen?

BibliographyBibliographyhttp://cagle.slate.msn.com/2000/2000gifs17/cartoon19991114.gifhttp://cagle.slate.msn.com/2000/2000gifs17/cartoon19991114.gif

(George Bush & Sept 11)(George Bush & Sept 11)

http://www.colorado.edu/geography/gcraft/notes/mapproj/mapprojf.hthttp://www.colorado.edu/geography/gcraft/notes/mapproj/mapprojf.htmlml

Daryl Cagle’s Professional Cartoon Index Nov 24/02Daryl Cagle’s Professional Cartoon Index Nov 24/02

In the Global Classroom 2In the Global Classroom 2 Graham Pike and David Selby Graham Pike and David Selby Pippin Pippin 20002000

A Geopolitical Atlas of the Modern WorldA Geopolitical Atlas of the Modern World 1995 1995

5 Essential Map 5 Essential Map componentscomponents

BorderBorder ScaleScale North Arrow/Compass roseNorth Arrow/Compass rose TitleTitle LegendLegend