Map Projections …are about presenting the round Earth on a flat surface. Dutch painter of the 1600s…this painted in 1669 Vermeer’s Cartographer

What is a map projection? A projection is a way to make a flat representation of the Earth

The only accurate representation of the earth is a globe. Only a globe preserves the map qualities of area, shape, direction, and distance.

Why are all map projections distorted? All map projections must distort size, shape, distance, or direction. Watch the following video to find out why: http://goo.gl/oxC3v

Why do we use maps vs. globes? Brainstorm advantages that maps have over globes and write them on the board. Portable, easily identify regions, easier to measure distance, is more specific in terms of information presented

Distortions Every map MUST and DO have distortions that result from making a 2D representation of a 3D sphere.

Types of Distortions Shape: the shape is wrong Area: the size is wrong Distance: distance between places is wrong Direction: direction is wrong (north/south aren’t the top and bottom of the map, east/west aren’t to the sides)

Types of Map Projections There are three main types of map projections: Cylindrical/Mercator Conic Plane/Planar/Polar/Azimuthal

For Mercator projections, please know the following: visual recognition accuracies distortions uses

Mercator/Cylindrical Projection Invented 1569, meant for navigating ships, direction is true-mimics a globe-lines of latitude/longitude are a right angles, show straight lines are loxodromes or rhumb lines-for “true” direction BUT Distorts size-esp. North and South Poles-imagine the orange peel again-as you stretch out the peel-the equator stay true to size but the poles are stretch out to try and make it lie flat

Visual Recogintion right angles At what angle to lines of latitude and longitude intersect on a Mercator/cylindrical projection?

Accuracy / Distortions Compare the size of landmasses on the Mercator/cylindrical projection on the left with the Robinson projection on the right to answer the following questions. 1. Which landmasses appear much larger on the cylindrical projection than they actually are? 2. Which landmasses on the cylindrical projection appear to be accurate in size? Those in the Northern Hemisphere and Southern-near the Poles Those closest to the Equator

Accuracy A C D B A:B – travel south from point A C:D – travel east from point C Yes, direction appears to be accurate What direction would you travel to get from ‘A’ to ‘B’? What direction would you travel to get from ‘C’ to ‘D’? Does direction appear to be accurate on a Mercator Projection?

Uses Watch the following video to see a common use of cylindrical/Mercator projections: http://goo.gl/obRzv Navigating the sea

Video of cylindrical/Mercator projection http://goo.gl/AE5bR

For Conic projections, please know the following: visual recognition accuracy uses

Conic Projection

Visual Recognition

Watch this: http://goo.gl/rJKp4 Answer these: What visual clue is covered that will help you recognize a conic projection? (visual recognition) What parts of the world do conic projections show accurately? (accuracy/uses) What is distorted, size or shape? (distortions) Longitude is straight but fans out, latitude is curved In the mid latitudes hemisphere-around US and Australia Size is distorted, shapes are correct

For Planar/Polar/Azimuthal projections, please know the following: visual recognition uses

Plane/Planar/ Polar/Azimuthal Projection

Visual Recognition

Accuracy Planar projections are accurate at the point the projection touches the map

Distortions: Shape distorted at edge of projection.

Uses: Great Circle Routes The line created when you cut the globe in half connecting two points

Uses: used by pilots because great circle routes appear as straight lines.

Compromise Projections What do you think a compromise projection is? Winkle Triple Robinson Projection

For Gall-Peters projections, please know the following: visual recognition Why is considered politically correct?

Gall-Peters Projection Compare the Gall-Peters(left) to the cylindrical projection(right). Both projections have latitude & longitude at right angles. What differences do you see between the shape/size of landmasses. Why is the Gall-Peters projection called the “politically correct” projection? Considered the “politically correct” projection--a response to the Mercator’s greater distortion of the size of landmasses in the northern hemisphere.

Equal Area Map area (size) is correct but other properties are distorted

Conformal Map shape is correct but other properties are distorted

VI. The Big Idea A. All map projections have distortions. B. Each projection has its own advantages and disadvantages depending on the purpose of the map.

Summary Video http://goo.gl/TG8XM