Task

Maps are literally everywhere. From outdoor wayfinding to decoration, they are so common that we often don’t even notice them. In your first task for credit, you will explore the ubiquity of maps in our built environment and describe one. This is a popular past time among map nerds – just do a search on your favorite social media for the hashtag #mapsinthewild.

You’ll need to explore your favorite places to find these maps. They are not printed maps that you buy for traveling (they still make those?) or pick up from tourism hosts. These maps are found in public places on signs, walls, floors, computer screens, etc.

Submitting the task

Upload your photo and text to the Module 3 discussion board on Canvas by the published due date. (2 points for the photograph and 1 point for each response.)

Lab

This lab introduces GIS, geographic information systems. Our goals are to get familiar with organizing and visualizing various spatial layers in QGIS, and begin formulating questions about our surroundings. You will not be making a finished map in this lab, but you will be creating a map that you can use in the field similar to our last module.

Table of Contents

• Introduction
  • Accessing the project and data
  • Viewing layers in QGIS
  • Exporting a map
• Video tutorial (20 min)
• Assignment
  • Deliverables
  • Submitting the assignment

Introduction

One of the fundamental questions asked in a GIS is: how much of x is in, or near, y? For example, how many people are within walking distance of a grocery store? What percentage of the city area is covered by impervious surfaces, e.g., roads, parking lots, etc? Which watersheds in eastern Kentucky have the most surface mining impact?

Answers to these questions are often used to make important decisions in public and environmental policy. While we will not endeavor to answer such questions in this lab, we will begin to explore the data and tools needed to do so. The approach is simple to understand: we overlay two or more layers of data in a GIS and then observe (and then measure) where features overlap, or are nearby.

In our lab example, we will focus on Kentucky and use layers for state parks, county population, and elevation. As we explore these layers in QGIS, we’ll wear our GIS hats and ask questions about spatial patterns in the state. In the next module, we’ll don our cartographer hats to best visualize the data.

Accessing the project and data

Begin by downloading the prebuilt QGIS project file and data, both stored in a zipped folder.

You should now have a folder called Kentucky_explorer with a QGIS project file and several data files. You should see the following files:

Contents of the Kentucky_explorer folder

Let’s take a moment to explore the contents of this folder. The QGIS project file is called Kentucky_explorer.qgz. This file contains the map layers, their symbology, and the map extent. However, the project file does not embed the other map layers. Instead, it references them by their file path. This is a common approach in GIS because it allows us to share the project file without having to share the data, which can be very large. So, we think of a map project as a collection of files in a folder.

The other files in the folder are spatial layers that you’ll add to the map. They are:

• CensusCounties_2020.geojson – Kentucky county polgons with population data from the 2020 Census. The format is GeoJSON, a popular format for sharing spatial data on the web.
• Kentucky_State_Park_Boundaries.zip – Kentucky state park polygons. The format is a zipped Shapefile. This format can be added directly to QGIS.
• Kentucky_State_Park_Trails_shp.zip – Kentucky state park trails. The format is a zipped Shapefile. (Note: A folder with the same name shows the contents of the zipped file.)
• ky-250.tif – Kentucky elevation raster showing elevation in feet above sea level. The format is a TIFF file, a popular raster format. The ky-250.tfw is a called a worldfile and allows QGIS to properly register the layer.

OK! If you see these files in your folder, you are ready to begin – and the hardest part is behind you. If you delete or lose this folder or its files, try redownloading the zip file and follow the first lab’s instructions for setting up your course folder.

Viewing layers in QGIS

Let’s open the QGIS project file and explore the layers. The elevation has already been added for you, but you might not see it at first.

You should see the following:

Open QGIS and zoom to elevation layer

As you can see, QGIS fits the entire state in the map canvas window. The elevation layer is a raster, which is a grid of cells, or pixels, that each have a value. In this case, the value is the elevation in feet above sea level.

Use the mouse wheel or the zoom tools to zoom in and out. You can also pan the map by clicking and dragging. See if you can find Lexington – there is only elevation to help you. One landmark to look for is the Kentucky River, which forms tall cliffs on our counties southern border.

The below images shows Lexington, the Palisades, and the Appalachian Foothills. We can determine that Lexington is higher than the river, but lower than the foothills. Can you find the highest location in the state, at 4,124 feet above sea level?

Darker or lightness of color shows elevation

Now lets add our first layer, the state park boundaries. We’ll use the drag-and-drop method.

You should see the following:

Drag and drop park boundaries layer to map canvas

Let’s find Lexington again and discover a few parks. While we can’t see through the polygons (yet), we have a good idea which parks are relatively higher and lower in elevation. This might seem like a trivial observation, but it is a fundamental concept in GIS: we can combine spatial layers to make observations about our surroundings.

Imagine this scenario. A threatened plant species is found only at high elevations in the state. Parks are often tasked with preserving biodiversity, so we might ask: where in the state are parks and do those parks have high elevations?

How would you determine which park is higher in elevation?

With a GIS, we could quickly find those locations in the state.

OK, let’s turn to our county polygon layer. The Shapefile format is a vector geometry format, but it can also store attributes for each feature. In this case, the attributes are demographic data from the 2020 US Census. We can use these attributes to change how the polygons look on the map. We’ll use the population attribute to change the color of each county polygon to show the number of people living in each county.

First, let’s add the county layer to the map and make sure the park layer is above the county layer.

Add counties layer and sort layer drawing order

The county polygons should be colored in a single color. This is the default symbology for vector layers in QGIS. Let’s change the symbology to show the population attribute. We’ll talk more abore symbology method in the next module. For now, we’ll use a method called Graduated to color counties such that darker colors represent higher populations.

You might first see a red color scheme; however, that can be changed via the Color ramp dropdown. You can change it to a blue color scheme.

The following image shows the steps:

Change how the county polygons look based on value for each county

We should now see the population of each county. The darker the color, the higher the population. For example, the darkest color represents those counties that have a population between 44,547 and 782,969. There is at least one county that has a population of 2,193 – can you find it?

The park layer is a bit lost on this map. We can change its appearance to make it stand out more.

The following image shows the steps:

Change how the park polygons look based on common property

We’ll ask another GIS question in a moment. First, let’s prepare the map for export.

Exporting a map

We should have a map that shows county population and parks. We are not making a finished map; only showing the steps to do so. The QGIS project has a prebuilt layout with the map added to an 11 x 17 inch page. Let’s open the page.

Open the QGIS Layout panel for exporting a layout

Most maps have a title, legend, scale, etc. We’ll only a text box that contains a question we might ask about our data.

The following two images shows the steps:

Add a text box to the layout

Change the text properties

When you are finished adding and customizing the text you should see the something similiar to the following:

How many people have good access?

With these layers, we can start analyzing and formulating questions about their spatial relationship. In this example, we ask how many people have good access to a park? An interpretation of good access could be: where there are more people there should be more parks. Another way to express this is that for every county, there should be an equal number of park acres per person. More the better, IMHO.

We have the data to start this analysis, but we’ll leave it for another course, e.g., GEO 309. But, you should now understand the basic concept of overlaying data and analyzing the results.

Now you are ready to export the map. Export the map as a PDF file and enable the GeoPDF option. This option will allow you to easily share the map and use it in Avenza Maps on our mobile devices.

The following images shows the steps:

Export layout as PDF file format

Enable GeoPDF option in export menu

Ok, you now have a PDF file that you can share with others. You can also open the PDF in Avenza Maps on your mobile device.

Video tutorial (20 min)

Assignment

Kentucky’s Creative GIS Club has a yearly competition where they invite mappers to ask interesting questions about the spatial relationship of two overlapping map layers. They have asked you to create a PDF that shows a map with two layers and one question. The question can be anything you want, but it must be answerable by the two layers you choose.

Note: You can use the map layers from this lab or find your own. If you use this lab’s layers, you should ask a different question than the one we asked in this lab.

Save your QGIS project often via the menu item Project > Save. If you want to move the project to a different computer, copy the entire folder, e.g., Kentucky_explorer.

Deliverables

Please follow these requirements for the assignment:

1. Add two layers to the map, making sure that both are visible. (4 points)
2. Experiment with styling of each layer to create enough contrast between the layers. For example, make one layer a cool color like blue and the other layer a warm color like yellow. (2 points)
3. Add a text box to the layout and write a question that could be answered by the two layers. (2 point)
4. Export the layout as a GeoPDF file.
5. Name the file cgc-{linkblue}.pdf and replace {linkblue} with your linkblue name. For example, cgc-elmus0X.pdf. (1 point)
6. Your TA will add one additional challenge.

Submitting the assignment

Upload your PDF file to the Module 3 assignment on Canvas by the published due date. After the submission deadline, we’ll try to answer some of the questions y’all ask during lecture.

Happy overlaying!

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