I need help to answers the attached lab questions please

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I'm working on a geology question and need support to help me study.

While the sizes of countries are more accurate in the AuthaGraph map above, what problems do you see that could limit the usefulness of this map?

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GST 101: Introduction to Geospatial Technology Lab Series Lab 3: Exploring Coordinate Systems and Map Projections Document Version: 2013-07-30 Organization: Del Mar College Author: Richard Smith Copyright © National Information Security, Geospatial Technologies Consortium (NISGTC) The development of this document is funded by the Department of Labor (DOL) Trade Adjustment Assistance Community College and Career Training (TAACCCT) Grant No. TC-22525-11-60-A-48; The National Information Security, Geospatial Technologies Consortium (NISGTC) is an entity of Collin College of Texas, Bellevue College of Washington, Bunker Hill Community College of Massachusetts, Del Mar College of Texas, Moraine Valley Community College of Illinois, Rio Salado College of Arizona, and Salt Lake Community College of Utah. This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this license, visit http://creativecommons.org/licenses/by/3.0/ or send a letter to Creative Commons, 444 Castro Street, Suite 900, Mountain View, California, 94041, USA. The Center for Systems Security and Information Assurance (CSSIA), in partnership with the Network Development Group (NDG) is given a perpetual worldwide waiver to distribute per US Law this lab and future derivatives of these works. Lab 3: Exploring Coordinate Systems and Map Projections Contents Introduction ........................................................................................................................ 3 Objective: Explore and Understand Map Projections and Coordinate Systems ................ 3 Lab Settings ......................................................................................................................... 4 1 Setting Map Projections and Coordinate Systems in ArcMap 10.1 ............................ 5 2 Exploring World Map Projections ............................................................................. 11 3 Exploring National Map Projections ......................................................................... 13 4 Exploring State Map Projections............................................................................... 19 Conclusion ......................................................................................................................... 21 Discussion Questions ........................................................................................................ 21 7/30/2013 Copyright © 2013 NISGTC Page 2 of 21 Lab 3: Exploring Coordinate Systems and Map Projections Introduction This lab is part of a series of lab exercises designed through a grant initiative by the National Information, Security & Geospatial Technologies Consortium (NISGTC), funded by the United States Department of Labor in partnership with the Department of Education under the Trade Adjustment Assistance Community College and Career Training Grant Program (TAACCCT). In this lab, the student will explore the effects of various map projections on the characteristics of a map using ArcMap 10.1. ArcMap 10.1 is part of the ArcGIS Desktop 10.1 suite of programs and is used to visualize, query, and analyze spatial information. This lab will focus primarily on shape and area distortions and will examine projections useful for mapping on the global scale as well as on the national and state level. Your instructor may require that you provide screen captures and/or exported files. Please check with your instructor for the requirements specific to your class. This lab includes the following tasks: 1. 2. 3. 4. Setting Map Projections and Coordinate Systems in ArcMap 10.1 Exploring World Map Projections Exploring National Map Projections Exploring State Map Projections Objective: Explore and Understand Map Projections and Coordinate Systems The map projection is a fundamental part of the mapping process, and provides the backbone, or framework, for the map. For the cartographer, selection of an appropriate map projection is a crucial part of the map design process. It is important for the map designer to understand the qualities of the mapped region that will be preserved by a given projection and the qualities that will be distorted or skewed. The transformation of the ellipsoid shape of the earth to a two-dimensional surface cannot be accomplished without some element of distortion, through shearing, tearing, or compression. For mapping small Earth areas (large scale mapping), projection is not a major issue, but as the scale becomes smaller, as in the mapping of continents or subcontinents, distortion becomes a significant factor. Distortion of area, shape, distance, and direction become properties to consider. It is impossible for one projection to maintain all of these properties simultaneously. Projections can be classified according to the properties they preserve. Equal-area (or equivalent) maps, for example, preserve area relationships, but tend to lose 7/30/2013 Copyright © 2013 NISGTC Page 3 of 21 Lab 3: Exploring Coordinate Systems and Map Projections conformality (preservation of shape). Conformal projections, on the other hand, maintain shape over small areas but produce areal distortion. In thematic mapping, it is frequently more important to maintain correct area properties, in that area is often an important element of what is being shown by the map. Therefore, shape is at times compromised through the choice of an equivalent projection. For small scale maps, in fact, conformality cannot be maintained over the entire area; rather, the projection may preserve shape best along a standard line, with shape distortion increasing with distance from the line. Another property to consider is distance preservation (equidistance), which preserves distance measurements along great circle arcs. Finally, direction preservation (azimuthality) maintains correct direction from one central point to all other points. There are hundreds of possible projections from which to choose. Some distort less in certain ways than others. It is up to the map designer to select the projection that produces the least amount of unwanted distortion. Many computer mapping software packages now allow the cartographer to easily switch between various projections, allowing the choice of the one most appropriate. In the selection of a projection, several key elements must be considered:     Projection properties - Are the properties of the projection suitable to the map’s purpose? Considering the properties of shape, distance, direction, and area, which ones must be preserved, and which can be sacrificed? Or is compromise of all four the best choice? Deformational patterns - Is the amount of deformation acceptable? Projection center - Can the projection be centered easily on the area being mapped? Familiarity - Is the appearance of the map recognizable to the map reader or will it detract from the map’s purpose? Lab Settings Required Virtual Machines and Applications Windows Machine User Account Train Windows Machine User Password Train1ng$ 7/30/2013 Copyright © 2013 NISGTC Page 4 of 21 Lab 3: Exploring Coordinate Systems and Map Projections 1 Setting Map Projections and Coordinate Systems in ArcMap 10.1 In this task, you will explore the effects of various projections on the characteristics of a map. We will focus primarily on shape and area distortions. We will examine projections useful for mapping on the global scale. 1. Log in to the computer using the settings provided in the Lab Settings section of this lab. 2. Copy the Lab 3 folder from the Shared_Drive\GST101 to the GST 101 folder you just created on the C: drive. 3. Click Start->All Programs->ArcGIS->ArcMap 10.1. ArcMap will open. 4. In ArcMap, close the Getting Started dialog box, and open the project, WorldView.mxd by clicking File->Open and browsing for the file in your newly created Lab 3 folder on the C:\ drive. After opening the file, you should see the map shown in Figure 1. Figure 1: WorldView.mxd Loaded into ArcMap 10.1 WorldView.mxd is a map document. A map document contains information about a map, such as: list of layers, coordinate system, symbols, labels, custom tools, map elements, and much more. In the map document, there are two polygon themes, Circles and Land, a point theme, Cities, and a line theme, Graticule. On this map, a projection has not been chosen in ArcMap. The software is using latitude and longitude measured in geodetic decimal degrees, which displays a simple rectangular coordinate system in which the length of one degree of longitude is consistently equal to one degree of latitude. In ArcMap, 7/30/2013 Copyright © 2013 NISGTC Page 5 of 21 Lab 3: Exploring Coordinate Systems and Map Projections when a projection has not yet been selected, distance calculations remain true, since the software computes distance using the spherical coordinates of latitude and longitude along a great circle arc, just as if you were actually measuring at the Earth’s surface. Although a projection has not yet been chosen by the user, the display is essentially a Plate Carree projection. On a projection that preserves shape, the polygons on the Circles theme appear as true circles. In a Plate Carree projection, linear scale, area, and shape are all distorted increasingly toward the poles as demonstrated with the Circles theme. The circles will be used in this exercise for illustrating the areal and shape distortion that occurs with various projections. While this method does not actually quantify the distortion, as does Tissot’s indicatrix, it does show visually the skewing, tearing, and shearing that occurs with certain projections. First, we’ll examine the map units and distance units set for this “unprojected” map. 5. From the menu bar, select View->Data Frame Properties. In the Data Frame Properties dialog box, notice the Map Units are set in decimal degrees and the Display Units are set in miles. This means the coordinates that are being mapped (in this case the boundaries of the land areas, the graticule, and the locations of the two cities) are stored in decimal degrees, and the measuring units are in miles. 6. Click on the Coordinate System tab. Notice that the current coordinate system is not specified. 7. Click Cancel to close the Data Frame Properties dialog box. Now we’ll do some distance measurements on this map for later comparison to maps in which a projection is set. 8. Click on the Measure tool, appear. 7/30/2013 , on the standard toolbar. The Measure box will Copyright © 2013 NISGTC Page 6 of 21 Lab 3: Exploring Coordinate Systems and Map Projections 9. Click the Choose Units dropdown and select Distance->Miles. Figure 2: Miles Distance Selection 10. Click the Measurement Type dropdown and select Planar. Figure 3: Planar Measurement Type 11. Click on the location symbol (star) for Atlanta, in the United States. 12. Move the cursor to the location symbol for Alice Springs, Australia, then double-click to end the line. The distance between Atlanta and Alice Springs will be displayed in miles in the Measure box. The measured distance is about 15,500 miles (your distance may vary slightly). This is not the actual distance between Atlanta and Alice Springs. Since the coordinate system is undefined in the Data Frame Properties, ArcMap measures directly between Atlanta and Alice Springs (along your measure line) heading East from Atlanta. What it should do is measure to Alice Springs by heading West from Atlanta instead of East as you defined since heading East is a shorter distance than heading West. However, ArcMap does not know that the “World is round” so-to-speak, since it does not know 7/30/2013 Copyright © 2013 NISGTC Page 7 of 21 Lab 3: Exploring Coordinate Systems and Map Projections that it is working with a World-based coordinate system. This view does not maintain spherical distance measurements, and distorts shape, direction and area. Let’s tell ArcMap that we are, in fact, working with a World-based coordinate system. 13. From the menu bar, select View->Data Frame Properties. 14. Click on the Coordinate System tab. a. Select the WGS 1984 coordinate system by expanding the following folders: Geographic Coordinate Systems->World. 15. Click the General Tab. Set the Display Units to Miles (if not already selected). 16. Click OK to view the map. 17. Measure the distance between Atlanta and Alice Springs again. The measured distance is about 10,030 miles (your distance may vary slightly). This is also the actual shortest distance between Atlanta and Alice Springs. This view is equidistant and maintains spherical distance measurements, but distorts shape, direction, and area. Let’s change the projection on this view to the Mercator projection. 18. Open the Data Frame Properties and select the Coordinate System tab. 19. Select the Mercator (world) coordinate system by expanding the following folders: Projected Coordinate Systems->World. 20. Click Apply to apply the coordinate system. 21. Click the General tab . Notice that the Map units are in meters. 22. Click OK to view the map. You should see the map shown in Figure 4. 7/30/2013 Copyright © 2013 NISGTC Page 8 of 21 Lab 3: Exploring Coordinate Systems and Map Projections Figure 4: Mercator Coordinate System The Mercator projection, a conformal projection (except at the extreme poles), has straight meridians and parallels that intersect at right angles. Scale is truest along the equator, and becomes more distorted at higher latitudes, as evidenced by the increasing size of the circles. The Mercator was designed for marine navigation and gives all straight lines on the map as lines of constant compass bearing. For global scale thematic maps, however, the Mercator has too much areal distortion for accurate use. Let’s see how the Mercator handles distance measurement. 23. Measure the distance between Atlanta and Alice Springs again, using the measure tool. The new measurement is about 15,647 miles, much more than the true distance. (Again, your measurements will likely vary somewhat.) The Mercator is best for larger scale projections of areas at low latitude. Small scale maps have much distortion of area and distance. Now, let’s examine the Behrmann projection. 24. In the Data Frame Properties, select the Behrmann (world) coordinate system by expanding the following folders: Projected Coordinate Systems->World. 25. Click OK to view the map. You should see the map displayed in Figure 5. 7/30/2013 Copyright © 2013 NISGTC Page 9 of 21 Lab 3: Exploring Coordinate Systems and Map Projections Figure 5: Behrmann Coordinate System The standard parallels are at 30 degrees North and South, so the least areal distortion will occur in these locations. The Behrmann Projection is a cylindrical equal-area projection that, as opposed to the Mercator, de-emphasizes area exaggerations in the higher latitudes. This projection was adopted by organizations concerned that the Mercator projection showed European dominance, in terms of area, over the Third World. It does preserve area, but there is shape distortion. The greatest shape distortion occurs along the equator and at the poles. Equatorial continents are stretched in a north-south direction. Let’s see how the distance property fares. 26. Measure the distance between Atlanta and Alice Springs again using the measure tool. Distance between the two cities in the Behrmann projection measures approximately 13,790 miles, still greater than the true distance. These two rectangular maps (the Mercator and the Behrmann) are much less desirable for mapping continents than other projections as they have significant distortion and can also promote geographical misconceptions. In general, rectangular maps are not recommended for use in mapping the world. Equivalency (the property of equal area) and conformality are better preserved using non-rectangular maps. In the next task, we will examine a map projection more suitable for mapping the world. 7/30/2013 Copyright © 2013 NISGTC Page 10 of 21 Lab 3: Exploring Coordinate Systems and Map Projections 2 Exploring World Map Projections Let’s examine a map projection more suitable for mapping the entire world: the Mollweide projection, a pseudo-cylindrical projection. First, let’s create another view in ArcMap so that we can compare the Mollweide projection to other map projections side-by-side. 1. From the menu bar, click Insert->Data Frame. A new data frame will appear in the Table of Contents. 2. Select all of the layers from the World View data frame by holding down the Ctrl key on your keyboard while clicking on each of the four layers. 3. Right-click on one of the selected layers, then choose Copy. 4. Right-click on the New Data Frame, then choose Paste Layer(s). The layers will be copied to the new data frame and the map will appear. A data frame is a collection of layers that, together, compose a map view. A map document (.mxd) can contain multiple data frames, each containing the same, or different data layers. To switch back and forth between data frames, right-click on the data frame you wish to see, then click Activate. The data frame’s label will become bold and you will see that map. Let’s now select the Mollweide projection in the new data frame. 5. With the new data frame activated, from the menu bar, select View->Data Frame Properties. The data frame properties only display properties for the activated data frame, which, in this case, is the new data frame that we just created. 6. Click on the General tab. We will provide the new data frame with a descriptive name for easy reference. 7. In the Name field, enter Mollweide Map Projection. 8. Click on the Coordinate System tab. Select the Mollweide (world) coordinate system by expanding the following folders: Projected Coordinate Systems>World. 9. Click OK to view the map. You should see the map shown in Figure 6. The Mollweide is commonly used for world maps, as it is equal-area and minimizes shape distortion, resulting in a map that is pleasing to the eye. Its central meridian, in this case the Prime Meridian, is straight, with other meridians curved. (Note: to specify a central meridian other than the Prime Meridian, double click on Mollweide (world) in the Data Frame Properties | Coordinate System dialog box, then enter a new value for Central Meridian) The parallels are all horizontal and straight. The linear scale is true along the parallels at 40o 30' North and South. 7/30/2013 Copyright © 2013 NISGTC Page 11 of 21 Lab 3: Exploring Coordinate Systems and Map Projections Figure 6: Mollweide Coordinate System Let’s see how the distance property fares. 10. Using the Measure tool, measure the distance from Atlanta to Alice Springs. The distance measures approximately 13,311 miles (You may need to change the units to miles if they are currently set to something different). The Mollweide is therefore not an equidistant projection. Let’s save our work so we can reference it later. 11. From the menu bar, click File->Save As… Name your map document and save it in your Lab 3 folder. 7/30/2013 Copyright © 2013 NISGTC Page 12 of 21 Lab 3: Exploring Coordinate Systems and Map Projections 3 Exploring National Map Projections Projections suitable for mapping the world are not necessarily the best for mapping smaller areas, such as continents or countries. When mapping at such a scale in the mid-latitudes it is important to use a projection that is centered on the area being mapped and has a standard line, or lines, passing through the area being mapped. In this task, we’ll look at a map of the contiguous United States using a few different projections. 1. In ArcMap, open the project, CountryView.mxd by clicking File->Open and browsing for your Lab 3 folder. CountryView.mxd is an “unprojected” map of the lower 48 states ...
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