1.3 Add Data to the Map

Now that you know how to manipulate the map, it’s time to begin modifying the map toward the goal you specified in Teachback 1. The first step is to add your own geospatial data to the map. Esri’s basemaps are great for providing geographic context, but you can’t modify them beyond selecting between the premade options, and they do not print well. To make your own map, you must first bring data into the project, then symbolize it to convey the insight you want your map’s users to gain.

Geospatial data are digital representations of geographic features. The real world is too complex to perfectly capture in a computer system, so map makers use the process of map abstraction to select and represent specific information about geographic phenomena that may prove useful. The most common ways to represent discrete features in GIS are as points, lines, or polygons. You can think of each of these as a different geometric dimension—points have zero dimensions (they are simply a pair of coordinates), lines are one-dimensional (they have only length), and polygons are two-dimensional (they have both length and width). Data representing discrete objects is called vector data. A GIS vector dataset typically consists of features that all pertain to one theme (such as roads, lakes, cities, etc.) at one dimensionality (i.e., all points, all lines, or all polygons).

Continuous geographic features, such as temperature or elevation, have no hard edges. Such features are not represented in GIS as sets of objects, but rather as raster data composed of a pixel grid, like a digital image. Chapter 2 will introduce raster data; for this chapter, we will stick with points, lines, and polygons. For further discussion of how maps represent the world, see Section 2.3 in the Campbell and Shin text.

Extract and store geospatial data

Before you load data into an ArcGIS Pro project, it needs to be stored somewhere on your computer. You should create a folder called “data” or “gis_data” somewhere it will be easy to find in your file system. This may be close to the root of the hard drive (C:\), or in a cloud file storage system like OneDrive or Dropbox. You may also need to extract the data from a Zip archive file (.zip) before it can be read by ArcGIS Pro.

The action sequence below assumes you have received data in a Zip file from your instructor, but the same steps apply for each dataset if you download the data yourself. It also assumes you might reuse the data for other projects. If you will only use the data for this project, you may wish to store it in the project folder that was created by ArcGIS Pro instead of a data folder in the drive root.

Action Sequence

1. Download the data you need for your map from the location specified by your instructor (or from online repositories given in Appendix A).

2. Open the Downloads folder in Windows Explorer.

3. Click on the Zip file you downloaded, then click the Extract tab (Figure 1.12).

4. Click the “Extract All” button.

5. Click the “Browse” button and navigate to a root folder where you want to keep your data. This may be the C:\ drive, a network drive, or a cloud storage backup folder like OneDrive or Dropbox.

6. If necessary, click the “New folder” button to create a new “data” or “gis_data” folder (Figure 1.13).

7. Click on your data folder, then click the “Select Folder” button.

8. Make sure the checkbox for “Show extracted files when complete” is checked, then click the “Extract” button.

Perception and Interpretation: When extraction is complete, a new window should appear showing the contents of your data folder. Move that window side by side with the Downloads window so you can see both. Double-click the Zip file in the Downloads window and compare its contents to what is in the data folder. The data folder should contain the contents of the Zip file.

Add point data to the map using the Catalog pane.

Once your data is extracted, you can add it to your ArcGIS Pro project. Adding data to the map using the Catalog pane is fairly straightforward, except that you must manually enable access to the folder holding your data by adding a Folder Connection.

Action Sequence

9. Open or expand your map project in ArcGIS Pro.

10. Switch the right pane to the Catalog pane if it is not already open. If you do not see the Catalog pane or a tab at the bottom of the pane for it, click the View ribbon tab, then click the “Catalog pane” button.

If you accidentally click the “Catalog Window” button, it will open the Catalog in the center view. This view of the Catalog works the same way as the Catalog pane, but is less conveniently located for adding data to the map.

11. In the Catalog pane, expand the Folders item.

12. Right-click the Folders item, then click “Add Folder Connection” (Figure 1.14)

13. Navigate to your data folder, then click the “OK” button.

Perception and Interpretation: An item for your data folder should appear under the expanded Folders item in the Catalog pane. If you expand this item and any subfolders, you should be able to see items for each of your datasets (see Step 14, below).

Evaluation: If you cannot find your datasets, they may still be stored in Zip files that need to be extracted. ArcGIS Pro cannot read the contents of a Zip file. Open your data folder in Windows Explorer and check whether there are any Zip files contained in it; if there are, extract their contents to the data folder.

14. Expand the item for your data folder in the Catalog pane, and expand any subfolders until you see an item for the shapefile containing your point data (it will have an icon with points on the left with a filename ending in a .shp extension). If you hover your mouse over the filename, additional information will appear (Figure 1.15).

15. Click and drag the point dataset onto the map until the cursor looks like an arrow with a small + sign under it, then let go of the mouse button to drop the data onto the map.

16. Save the project.

Add line data to the map using the Add Data button.

ArcGIS Pro provides multiple ways to do pretty much every GIS operation. The next set of steps walks you through a second way to add data to the map. The results are the same as dropping the data in from the Catalog pane, so which method you choose in the future depends only on your personal preference.

Action Sequence

17. From the Layer group in the Map ribbon tab, click the “Add Data” button, or click the “Add Data” dropdown arrow and then click “Data” (Figure 1.16).

18. In the Add Data window file tree, under “Project”, click the “Folders” item (expand “Project” if you don’t see it). In the main part of the window, you should see the project folder and your data folder, which you connected in Steps 12 and 13. If your line dataset is in a different folder, navigate to it under the “Computer” item at the bottom of the file tree.

19. In the main part of the Add Data window, double-click your data folder to enter it, and enter any subfolders that your line dataset is inside of.

20. Once you find your line shapefile, click on it once, then click the “OK” button.

21. Save the project.

Perception and Interpretation: The line data should appear on the map and an item for it should appear in the Contents pane.

Add polygon data to the map.

Action Sequence

22. Use the method of your choice to add your polygon data to the map.

23. Save the project.

Perception and Interpretation: The polygon data should appear on the map and an item for it should appear in the Contents pane, along with items for the point and line datasets.

Hey! Where are my layers?!

It is important to understand that ArcGIS Pro map files (.aprx files) do not embed the datasets used in a project. When you add data to your map, ArcGIS Pro simply creates links to the data wherever it currently exists on your computer or network; it does not create any new data. This can cause problems if you copy or move the .aprx file, or store the data in a location that you only have access to on one machine (such as its hard drive) and try to open your project on a different one.

If you open your project from a location where you do not have access to one or more of the project datasets, you will not see the affected layers on the map, and each will be listed in the Contents pane with a large red exclamation point between its checkbox and its filename (Figure 1.17). If you click on the exclamation point, a Change data source window will open that will allow you to find and reconnect to the missing dataset. If the dataset is not available on the machine you are using, you will need to download and extract it again before you can restore the link and move on.

Practice: You can intentionally break a dataset link to simulate losing access to the data and practice what you would do to recover it. Make sure your project is saved, then close ArcGIS Pro. Open your data folder in Windows Explorer, create a new subfolder, and move everything that was in your data folder into the new subfolder (select all files, then drag and drop or cut and paste). Then reopen your ArcGIS Pro project and try reconnecting one of the broken dataset links. When you are finished practicing, close the project without saving and move your data back to where it belongs in the data folder.