GOG 290- Introduction to Cartography

Lab practice 2: Seeing a flight path as a passenger and pilot

Introduction

This lab intends to give you more hands-on experiences about how projections work in general and how you can manipulate them on maps through different projects. Like what the lecture introduces, the map we see on a flight as a passenger is different from what a pilot sees in the cockpit, all because of the projection for preserving a certain property.

Please answer the eight questions on the provided Word template and organize them.

Learning objectives

This lab’s goal is to help us get familiar with the GIS software and work with projection and scale that will work towards our mapping purpose:

1. Familiarizing with the different projections and changed views in GIS software;

2. Changing scale to view different distortions of geographic regions;

3. Understanding the changes of properties when projection changes.

Procedures

Let’s go straight to the steps where you can start working with maps and different projections inArcGIS.

1. Download the map data from the Brightspace (Lab2 Data)

2. Once you download the folder, it probably ends up in your Downloads folder. Feel free to save it so anywhere you prefer on your computer.

3. Extract (or you may call it Unzip) the zip file and make sure the extracted folder is still at the location that you can retrieve later. (You may be able to click through the zipped folder and see your file. But ArcGIS Pro does not unzip it for you automatically so you may not be able to add your layer)

4. Start ArcGIS Pro. You can find it by clicking the Start button and typing ArcGIS Pro in the Search window. ArcGIS Pro should come up as an option. Click on it to start it up.

5. You’ll be prompted to create a new project. Click on the Map icon to start anew map project. You can change the path to save your project at your preferred location with a name such as Lab 2.

6. Under the Map tag, Click the Add Data button . Browse to the folder where you downloaded and extracted the Lab 2 Data. You will see the following dialog box (you probably won’t see the same folders, though)

7. Select country.shp and click Add. You should now see the world rendered as borders of countries.

8. Right-click the Map in the Contents Panel on the left and choose Properties. This is the Properties for Data Frame. Click the Coordinate System tab and you will see this:

9. You will see two folders called Geographic Coordinate Systems and Projected Coordinate Systems. Choose Projected Coordinate Systems, then World. Select Mercator (world) and click OK. You should now see the earth projected into Mercator X,Y coordinates.

10. Time to create a flight path! Any line representing a course of constant compass bearing will draw as a straight line in the Mercator projection. So let’s make one.

11. Click the Add Data button and select LineShapefile.shp (it should be in the same folder as country.shp). Now click the Add button and it should appear in your Table of Contents on the left, above country. This is just an empty layer for you to draw on so no new features will appear right now.

12. Click Edit tab then Create. In the Create Features panel on the right, click the LineShapefile. We you then see options of the types of features to create.

13. You are ready to create a path on the map. Since you have selected LineShapeFile, your edits will appear in that shapefile. Click the Line icon which is the first option.

14. Create a route from New York to Paris (close enough is fine here) through a series of short straight-line segments. (In reality, an airplane would fly over a set coordinates, so the airplane would maintain on the great circle route. What we are trying to do, is to simulate and visualize a route that fly over a set of control points. WARNING! DO NOT CREATE ONE SINGLE STRAIGHT LINE FROM NEW YORK TO PARIS). You may find it easier to do this if you are zoomed in so that New York is on the left edge of the data frame. and Paris is on the right. To create this series of short lines, click on New York, and, while envisioning a straight line path to Paris, click to make at least 10 line segments by clicking the cursor all in a straight line, ending at Paris. Do the best you can. The straighter, the better.

15. When you end up at Paris, double-click and then save the edits. Your path should appear on the screen.

16. Bring up the Map Properties dialog box again and look at the Coordinate System tab. In the Projected Coordinate Systems, choose Polar. Select North Pole Gnomonic. You will now see the world and your path in that projection. Zoom out until you can see your whole path.

Question 1: Is your path still a straight line? (5 points)

17. Now repeat steps 12-16 but drawing a straight line with 10 line segments from New York to Paris while you still have your map in the North Pole Gnomic projection. When you have completed all the steps, project back to the Mercator (world) projection.

Question 2: Is your first path still a straight line again? Is your second path still a straight line? (10 points)

18. Bring up the Data Frame. Properties dialog again. Select the North Pole Gnomonic projection again and then right click it. You can then change the latitude and longitude of the center of projection to a spot in the North Atlantic Ocean by choosing Copy and Modify. Change the Latitude of center to 45 from the default 90, and longitude of center to -30 from the default 0. Click OK and OK again.

Question 3: How did the view change? (10 points)

19. And now again change the center of projection approximately to our location at Latitude 42.5, longitude -73.5. Zoom in on New York State using the zoom tool .

Question 4: How would you characterize the distortion in the New York state region? Zoom out until you can see as much of the world as ArcMap will allow. How would you characterize the view near the edges of the map? What can you infer about the relationship between scale distortion and proximity to the center of projection? (25 points)

20. Add a grid of latitude and longitude lines (a ‘graticule’) to your map. To do this, create New Layout under Insert tab. Once you on a new layout page, click Map Frame. to draw a new rectangle. The map you worked on earlier will appear, click on it here, and then draw a rectangle to insert it. Once you finish drawing the rectangle. Then click the Grid to select one of the grid designs. You will then have a new grid called Graticule.

21. Your map should still be under the North Pole Gnomonic projection with the projection center at New York City.

Question 5: The Gnomonic projection shows all great circle arcs as straight lines. (15 points)

a. Are the meridians (lines of longitude) being drawn as straight lines?

b. How about the equator?

c. How about the other parallels (lines of latitude)?

Question 6: (10 points)

a. Does the first line that you drew make constant angles with respect to the lines of longitude that it crosses?

b. What does that tell you about direction of travel along that course?

Question 7: (10 points)

a. Does the second line make constant angles with respect to the lines of longitude that it crosses?

b. Again, what does that tell you about the direction of travel along line number 2?

Question 8: (10 points)

a. Which of the 2 paths provides the shortest distance from New York to Paris?

b. Which of the 2 paths would be easier to follow if you didn’t have an autopilot mechanism to set your course?

22. Save your map project. To avoid incompatibilities, follow this procedure: Select

File…Save a Copy…

Give the file a name and save it to your computer. You are not required to submit this project file but can do so as a backup. You must submit your completed template as your Lab 2 report.