Science

You will be evaluated the same way you have for previous labs.

There are two parts to this lab…

Learning Outcomes for Lab:

1. Distinguish between Geographic Coordinate Systems and Projections

2. Evaluate the best projections for a specific geographic area

3. Calculate/Convert Latitude and Longitude coordinates into different forms

4. Assign projections to different geographic areas based on location and geographic extent

5. Differentiate between different kinds of projection families

6. Become familiar with the effects of different projections (distortions of size, shape, distance, and direction) – particularly the Mercator projection.

Learning Outcomes for Quantitative Literacy:

· Understand quantitative models that describe real world phenomena and recognize limitations of those models;

· Perform simple mathematical computations associated with a quantitative model and make conclusions based on the results;

· Recognize, use, and appreciate mathematical thinking for solving problems that are part of everyday life;

· Understand the various sources of uncertainty and error in empirical data;

· Retrieve, organize, and analyze data associated with a quantitative model; and

· Communicate logical arguments and their conclusions.

Part I - Displaying Different Projections

Please navigate to http://projections.mgis.psu.edu/.

This site allows you view the entire Earth surface, or portions of the Earth surface, using a variety of map projections.

Introduction to Projections

Please watch this video for a general background of projections

WHAT IS A PROJECTION AND WHAT DOES IT DO?

Projections are a mathematical conversion of the globe from a 3D roundish surface (geoid) into a 2D map.

The earth is a real place with a roundish shape. All maps were once globes. They all metamorphasized from globes to maps. This transformation has effects on consequences for the how the map looks/appears/does

This transformation distorts four properties: shape, area, distance, and direction.

Depending on what projection you pick (at the world scale) at least one of these qualities will be distorted.

WHAT PROJECTION SHOULD I PICK?

Pick a projection based on

a) the size of the area we are mapping

b) the location of the area we are mapping

c) the properties of the map we want to preserve

This lab is an exercise in identifying, manipulating, and choosing between projections. Which projections are there? Which one is best for what kind of map you are trying to make?

There can be no maps without projections – manipulate them to best communicate your message and execute your purpose.

WHATS UP WITH THE WEIRD GRID LINES ON THE DIFFERENT PROJECTIONS?

Hold up… why are the lines different on these maps? Each of these maps is the same model of the earth but projected onto a different surface.

The top projection is projected onto a flat surface or a plane

The middle projected is projected onto a cone

The last is projected onto a cylinder

The properties of the surface the globe is projected on warps and shapes the gridlines on the map (lat and lon) as well as the size, shape, distance, and direction of the map.

The larger the area we map the more distortion there is. We could get a map of Philadelphia pretty close to accurate but this is impossible at the world scale. No matter what we pick – lot’s of distortion.

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Questions…

Navigate to http://projections.mgis.psu.edu/

You should see the Robinson projection. The Robinson is a compromise projection for the world that takes into account small distortions for shape, size, distance, and direction.

1. Why do you think this projection is a favorite of Atlas makers and folks who speak to general (not expert) audiences?

It is the favorite to Atlas makers as well as people who speak to the general audiences because of the fact that it shows our entire world all at once and it the best way of showing the whole world in a form of a flat image due to better balance of shape and size.

2. Why do you think the edges of a Robinson projection are curved? What does the curve represent?

The edges of a Robinson projection are curved to enable the locations located at the poles not to appear as points, but stretch the poles to become lines. This curving prevents the compression of landmasses that are located at the poles. The curve is a representation of the meridians.

3. Who is Arthur Robinson? How did he change the mapping game?

Arthur Robinson was a geography professor from Wisconsin, who came up with the Robinson projection which ended up becoming a more popular projection that initially popular Mercator projection for representing world maps on a flat plane. It came to be preferred because the Mercator projection has inherent distortions that made map makers to dislike it. Robinson thus came up with a projection that produces maps that look more like reality. He introduced a projection for which both the latitude and longitude lines are evenly distributed across the map in terms of spacing and that involves less distortions at the map’s Polar Regions.

Change your projection to Albers Equal Area Conic and press reset map. This is an accurate projection for mapping the entire United States because it has two standard parallel and can preserve accuracy along large east-west extents.

3. Name two ways that the Albers Equal Area Conic projection is different than the Robinson Projection?

One way in which the Albers Equal Area Conic projection is different from the Robinson Projection is that it distorts shape. Secondly is that it distorts size.

4. What do these projections (Robinson and Albers Equal Area Conic) look different from another?

Robinson projection is pseudocylindrical projection while Albers Equal Area Conic projection is a conic projection.

You may have noticed that the Albers Equal Area Conic map has standard parallels. At 20 degrees north and 60 degrees north. This means that the map distorts size, shape, distance, and direction the least at areas on these latitudes. We use this projection for North America because the continent can be fully encompassed with these touch lines. If we were to map South America or Southern Africa our map would be distorted. If we were mapping Russia we might pick latitudes ranging further north.

Do you see how the cone is being placed over the globe? Where the cone touches the globe is where characteristics of the globe (area, shape, distance, and direction) will be most accurate on the map. These are called touch lines – as you travel further away from the touch lines, the map gets less accurate. This projection is a secant projection – because it has two standard parallels.

5. Change the standard parallels to -20 and -60 and update the map. (You still be on Albers Equal Area Conic). Snip or take a picture of your map. What appears to be different about the map? What area (pick just one) of the world would be best for this projection?

Image of -20 and -60

When the standard paralles are changed to -20 and -60, the projection seems to get inverted in that it moves to the upper part compared to when the parallels were 20 and 60. The part of the world that seems to be best represented by this would be the map of Australia.

6. If you wanted to map Thailand which parallels would you choose?

The parallels that I would use would be 20 and 60.

7. If you wanted to map Argentina which parallels would you choose?

I would use -20 and -60.

Now choose the Mercator Projection.

Question: What quality (size, shape, distance, or direction) is most obviously distorted on this map?

Size is mostly obviously distorted.

Question: Remember what standard parallels and touch lines are? The Mercator is a tangent map – it only has one touch line or standard parallel).

a) Where do you think the Mercator touch line or standard parallel is (which latitude)

It is at the equator.

b) How does the location of this line explain the distortion on the map?

As you move away from the equator, the distance between the latitudes increases, while the distance between longitudes always remains constant. This is the relationship that always allows direction between any given two points to remain as constant true direction on the map. On the other hand, as the direction is maintained distortion to shapes, distances, and areas is allowed.

Question: Please take 3 snips from the application that demonstrate the 3 different families of projections (Cylinder, Cone, Plane)

Cylinder

Cone

Plane

Part II

Examine the following map that I made of selected wetlands in the Eastern Portion of the United States.

Your job is to find the best projection for each of these wetlands. Remember you want to limit the amount of distortion on your map. You want to map close to touch lines that preserve distance, size, direction, and shape.

There are two types of projections you will choose from – UTM or Universal Transverse Mercator or State Plane.

For each example below either choose a specific UTM Zone (Please include what zone you choose), indicated in bold/black on the UTM map below or a specific state plane zone (please indicate the specific zone), indicated on the bottom map (two or three letters) in the beige color.

Things to think about as you make your selection...

The UTM is a secant projection - it’s similar to the Mercator you examined before, but turned on its side. Each UTM zone is a specific manipulation of this projection. Distortion is the least when it is closest to one of the meridians. (These are just like standard parallels but instead of running east to west they run north to south)

State Plane Systems are used by government and business to find a coordinate system that best works for a smaller region of the United States. Larger states are split into two or three systems. As a general rule - if your wetland falls within the state plane area you should use that state plane area. If it crosses several state plane areas, you will probably want to use the Mercator.

Choose the best projection for mapping each wetland and explain in one or two sentences why you chose it:

Upper Mississippi River Floodplain Wetlands

UTM Zone because it is close to the meridian. Chesapeake Bay Estuarine Complex

The Mercator because it crosses several state planes.

Caddo Lake

The Mercator. This is because it is located in the border of two states.

Congaree National Park

State plan area. This is because it falls within a state plane area.

Okefenokee National Wildlife Refuge

The Mercator because it is located at the border of two states.

Everglades National park

State plane area because it is located within a state plane area.