MappingBasics This worksheet will walk you through the basics of creating a digital map using CARTO, a cloud-based GIS and web mapping tools platform. The goals of this exercise are: Learn how to geocode information about places to make it suitable for mapping Learn how to create a basic map representing points of interest Gain familiarity with a popular mapping platform that requires no software installation and which offers a free tier sufficient for basic use TheCARTOinterface The CARTO application uses the metaphor of a dashboard. The are two main screens that we will use for building maps: the "Datasets" screen and the "Maps" screen. From most parts of the application, these can be accessed from the drop-down menu at the top of the window.
Dataformapping In order to begin building our map making skills, we need certain kinds of information about the things we want to represent on the map. Depending on the map we want to make and the work we want it to do, we will need different kinds of information. If we want to use digital mapping tools, we will need to make sure that geographic coordinates are part of the information we maintain about place. Digital mapping systems are based on geographic coordinates measured in units of latitude and longitude, which refer to positions on the surface of the earth. People have multiple ways of providing information about place:
Baltimore, MD 123 Easy Street, Hometown, 45678, USA U Street NW and 14th Street NW 2 miles south of Interstate 495 We have to translate any information we might have about locations into the geographic coordinate systems used by mapping applications - a process that is called geocoding. Mapzen, another digital mapping platform, explains it this way: There s nothing inherent in the language we use to describe a physical address that allows us to convert that human readable sentence into a format that a computer can understand, such as latitude & longitude. We're going to explore how to geocode our information about places interactively using familiar tools like Google Maps. Basicgeocoding ByhandusingGoogleMaps The simplest way to get geographic coordinate data is to use a familiar service to gather this information for each place individually. For example, if we wanted to find coordinates for the new Harriet Tubman Underground Railroad National Historical Park opening in Spring 2017 on Maryland's Eastern Shore, we could:
Navigate to Google Maps and enter our query in the search box. When we hit enter, the map view will change moving and zooming in to show the result of our search. To get coordinates, right click on the place we're interested in
this will bring up a contextual menu. Select "What's here?". This will drop a point marker on the place you selected and open a small info box containing box a street address and a set of geographic coordinates.
Copy the geographic coordinates for use in your mapping project. NB: The coordinates here are presented in LATITUDE, LONGITUDE order. (This won't be the same across every geocoding service due to different standards for recording geospatial information). Repeat as necessary for all the places you need to geocode. UsinggeocodeddatainCARTO Let's look at the dataset we'll be using in this exercises. Navigate to the "Black Broadway on U" dataset it's available from Google
Drive at https://go.umd.edu/aadhum-incubator-2. This dataset has two sheets, each with seven columns. (The seventh column may be hidden when you visit the page for easier reading.) We need to export this data as a comma-separated value (CSV) file to use in CARTO. Make sure the sheet titled "Step 1" is active. Then selected "Download as" from the "File" menu and choose "commaseparated values (.csv, current sheet)". Note where this file is saved when you download it. Next we're going to upload this file as a dataset to CARTO. Navigate to CARTO and login to your account. Select "Datasets" from the pulldown menu at the top of the screen to navigate to the "Datasets" screen. Click the "New dataset" button at the upper
right. On the subsequent screen, select browse and choose the CSV file you downloaded to your computer from the file browser window that opens.
The CARTO interface will show an icon for the file you've selected and the "Connect dataset" button will turn a brighter blue color. Click the button to continue. A progress window will appear in the lower left. When the dataset has been uploaded, it will appear as a table in the CARTO interface.
Notice that a couple of new columns have been added including one called "the_geom", which contains the values for latitude and longitude together. This tells us that CARTO has analyzed the file we uploaded and indentified the geographic coordinates. Click on the "Create Map" button at the bottom right. When the map appears, you'll notice it is zoomed in and positioned
to display the points in our dataset. In the menu panel on the left, you can see the different layers comprising our map. There is a layer for the dataset we just uploaded but there is also the "Basemap" layer, and a layer containing the text labels for places in the basemap. If we click on the name of the layer with our dataset ("aadhumincubator "), a new menu will appear on the left side of the screen giving us the ability to style our layer. For example, we could change the color of the points to make them easier to see.
Explore some of the other ways you can change the appearance of your map data. You might also want to try: Changing the style of the basemap Adding information to labels that popup when you click on a point Changing the style of the map markers. (Try the "Heatmap" view)
Geocodingmoredata Let's return to our "Black Broadway on U" dataset. (Remember it's at https://go.umd.edu/aadhum-incubator-2.) Navigate to "Step 2" and use the skills we learned above to add latitude and longitude for the places in this sheet.