4B: Web Mapping 101

The past decade has witnessed a proliferation of web mapping tools and platforms.  These tools have long allowed the simple display of and basic interactions with spatially referenced data, but until recently, if you wanted to do any sort of analysis you had to use a desktop GIS system.  That situation has begun to change, however, and there are now many solutions out there for mapping your own data alongside hosted layers from around the web.

There are a lot of open source GIS options out there (see this list for a complete rundown) and which one will be right for you depends on the needs of your project and your familiarity and comfort with coding.  Today we’re going to explore some of the most common web mapping platforms out there and see how you can start making fairly complex maps with relatively little startup cost.

 


Google Maps / Fusion Tables / API

Google’s mapping products are the most well known to the general public, since Google Maps and Google Earth have been around a long time and are ubiquitous.  For an example of how to use the API, let’s briefly the 2015 Google Maps API tutorial.

First, let’s look briefly at Google’s newer offering, Fusion Tables, which offers a dead simple way to convert a spreadsheet with location data into points on a map.  This can be great to get a first look at your data, and do some basic filtering, but if you want to do any more complex visualization or analysis you need a more powerful tool.

Getting Data to Map

  1. For today’s exercises, we are going to use a dataset that is, at least thematically, relevant to our interest in the early history of Carleton.  Our dataset can be accessed in the shared folder at this link.  (The file, early-colleges.csv, is part of Lincoln Mullen’s historydata datasets on GitHub.)
  2. Download the CSV and open it in Excel or a text editor to see what you will be mapping. Screen Shot 2015-10-08 at 6.39.17 AM

    1. What information does this file hold?
    2. Where is the spatial data? What kind of spatial data is there?
    3. Where might it have come from?  How reliable do you think it is?

 


ArcGIS Online

ArcGIS is the industry leading GIS platform.  It is very powerful, very difficult to learn, and very expensive, since it is proprietary software created and owned by a company called ESRI.

ArcGIS Online is the company’s attempt to reach a more mass market audience.  It is a cloud-based GIS service that offers an easy way to add, store, and visualize spatial data, much like Fusion Tables.  But ArcGIS Online also offers sophisticated ways to analyze data that until recently were only available in high-end desktop software, and — crucially for humanities projects — any map you create can be turned into a Story Map like the Battle of Gettysburg example we looked at last time.

As with the desktop version, ArcGIS is not free, however.  It does offer a public version, but it is very limited and offers no analysis capabilities.  “Subscription” accounts for organizations start at $2,500/year for 5 users — not exactly cheap.  We are going to use it in this class, because we are fortunate that Carleton has a  subscription and excellent support in the person of our GIS specialist, Wei-Hsin Fu.  But I’ve also included information on open source alternatives at the bottom of this post.

 

Logging in to your College Account

  1. In your email account, you should have received a message from ArcGIS Notifications.
  2. Follow the link in the email to the Carleton College ArcGIS Online homepage (or go directly to carleton.maps.arcgis.com). You will be prompted to sign in to the account. Choose the Carleton College Account option and enter in your account information on the following page.ArcGIS_-_Sign_In

Creating a Map

      1. In ArcGIS Online, click on the Map tab at the top of the page to bring up the main map editor window
        Carleton_College
      2. Explore the main map interface.  A few things to notice
          1. There are three Guided Tours to get started (we’ll go over these in detail, but you have some built in help here)
          2. The main operations you can perform are listed across the top menu.  What can you do with a blank map?  What can’t you do yet?
          3. Note the relationship between the scale bar and the zoom control as you navigate around the map
          4. What data do they give you by default?

        ArcGISOnline

      3. Click the Basemap tab and explore the options.  Pick one that is fairly neutral as a background to our data.Screen Shot 2015-10-08 at 11.26.59 AM

Upload and Map our Data

Now lets add our data to the map.  There are two ways to do thisScreen Shot 2015-10-08 at 11.29.35 AM

  1. Click Add and choose to Add Layer from File then navigate through your computer to find the file you want.  Note the types of files they allow you to upload
    • You can import a zipped shape file (ZIP: the default ESRI format for desktop GIS that is widely recognized by other GIS and web mapping platforms)
    • a comma, semi-colon, or tab delimited text file (CSV or TXT: this kind of tabular data is the most common way to collect your own information and will be portable just about anywhere, not to mention about as future proof as you can get
    • a GPS Exchange Format (GPX: this is data upload from a GPS tracker, say following a route you ran or biked that was logged by your phone or another GPS enabled device)
  2. Drag and drop a file onto the map window

The second option is much easier and quicker, but either way, find “early-colleges.csv” and upload it.  You should be presented with the following import options
Screen Shot 2015-10-08 at 11.37.09 AM

Like Google’s Fusion Tables, ArcGIS Online is going to try to geocode your data and provide latitude and longitude coordinates for any place references in your data set by comparing them to a gazetteer (a place-based dictionary) somewhere.  It should have correctly recognized the city and state columns as Location Fields

  1. Click Add Layer and see how it did.
    1. Click on a couple of the points on your new map at random to verify if they look correct.  The geocoder is pretty good, but ArcGIS does not provide much in the way of error checking and you can’t easily tell what it got wrong just by looking.  Buyer beware!

Symbolize and Visualize the Data

By default, the application will try to figure out some pattern in your data and will suggest an attribute to symbolize by.  Already, we can see the benefits of a more robust GIS over the simple uniform symbols used on the Fusion Table map.Screen Shot 2015-10-08 at 11.49.06 AM

  1. Explore the style options down the left hand column.
    • How do the data look if you choose a different attribute to show?
    • How do the single symbol, heat map, and types options differ?  Which is most appropriate for these data?
    • Explore the various symbolization options under the Types (Unique symbols) drawing style.
      • Figure out a map display that you are comfortable with and press DONE when you are finished.

Now that you have mapped some data, what else can do with it?Screen Shot 2015-10-08 at 11.53.59 AM

  • Check out the options below the layer and see if you can do the following
    1. Show the table of the data.  How is it different than or similar to the original CSV?
    2. Create labels for the points that use an appropriate value from the data table, and change the style to your liking
    3. Configure the Pop-Up to show a Custom Attribute Display and combine the data from several fields into a sentence.
    4. Enable Editing 
      1. Change the value of a point already in your dataset
      2. Add Carleton College to the data set

So what?  Asking and Answering Questions

We’ve got a map, but what does it tell us?  What can we learn from it that we couldn’t learn from reading the data in a table?

One of the greatest benefits of a GIS system is that we can compare different types of data based on their geographic proximity and spatial relationships.  ArcGIS online allows access to a multitude of other datasets hosted on its own servers and around the internet.  Let’s see how our data look compared to other information.  Can we make it tell other stories of interest?Screen Shot 2015-10-08 at 12.21.38 PM

  1. Click Add again, but this time choose Search for Layers
    • See if you can find some boundary layers, population data, or land cover information that seems to have a relationship with the colleges that might be meaningfully interpreted.

You might also search the internet for other GIS datasets that might be fruitfully compared.

  1. For instance, the Railroads and the Making of Modern America project has several data sets available for the growth of railroads
    1. Go to their data download page and get the shapefiles for the railroad system
      1. You’ll need to Zip (compress) the individual year folders in order to upload them, but once you do see if there is any correlation between the growth of railroads between 1840, 1845 and 1850 and the spread of the colleges.

Save and Share your map

Click Save on the toolbar to title your map and save it to your account. You will need to enter in a title and tags. The map description is optional. Click Save Map when you are satisfied with your descriptions.

Screen Shot 2015-10-08 at 12.37.52 PM

You can share a link directly to this map view, but you can also publish a nicer looking layout to share publicly.

  1. Click SHARE on the top toolbar. A new window will pop up. Choose to share this with “Everyone” and then click on Create a Web App.Screen Shot 2015-10-08 at 12.40.36 PM
  2. In the next window, chose the format of the web application. There are many options and you can preview them by clicking on “Create” then “Preview”. Once you find a template you like, click on “Create” then “Create” again.
  3. On the next screen, enter a title and summary for your application (it can be the same as your map title and description). Click SAVE AND PUBLISH.

Congratulations! You’ve made a live interactive web map!

FINAL STEP

  1. Create a new blog post on your personal WordPress site and embed the new map.
    1. Write a few sentences explaining what it is and how you made it.

 


Open Source Alternatives

CartoDB

CartoDB is a “freemium” service, that offers an entirely cloud-based all-in-one mapping service.  You can upload your data, perform analyses, and publish from their servers to the web through a very simple and clean user interface. They also offer one of the best styling interfaces around with many nice looking templates and the ability to tweak them or roll your own using the equivalent of CSS for web mapping that is called, appropriately enough, CartoCSS.And it’s all open source!

One of the big benefits of CartoDB is their “torque map” feature, which allows you to animate your data with minimal effort.  In the map below, I’ve uploaded the same early-colleges.csv dataset and animated it so that colleges pop up in the order of their founding.

We won’t go into detail on CartoDB here, but I encourage you to explore on your own with the same data or a different dataset to see how this tool compares with ArcGIS Online.

Lincoln Mullen has put up a great getting started with CartoDB tutorial that you can use to create an account and follow along, and CartoDB has an extensive series of tutorials to explore its features in more depth.

 

WorldMap

WorldMap is an open source project developed by the Center for Geographic Analysis (CGA) at Harvard with the aim of filling the gap between powerful but hard to learn desktop GIS applications and lightweight online map viewers.  You can easily create your own map layers in standard, exportable formats, and you can also view the many maps created by others, including Africa Map, the project that launched the program, and a Tweet Map, a great example of a “big data” geographic data mashup.

Screen Shot 2015-10-08 at 5.12.21 AM

WorldMap also hosts its own instance of MapWarper, which will let you georeference an image for free.

 


Assignment

The blog assignment for this weekend is to work on your final project proposal with your group.

For full instructions see the Assignment 1 — The Pitch (Week 5) on the Final Projects page.

 


Resources

 

4A: Spatial Humanities: GIS/Mapping 101

For the next week we will be exploring the spatial humanities — a vibrant and increasingly popular area of digital humanities research.   Humanities scholarship is currently undergoing a “spatial turn” akin to the quantitative, linguistic and cultural “turns” of previous decades, and many are arguing that the widespread adoption of Geographic Information Systems (GIS) technology and user-friendly neogeography tools are fundamentally reshaping the practice of history and other disciplines.  Yet while these powerful computer tools are certainly new, the mode of thinking “spatially” is not unprecedented, and may in fact be seen as a move away from the universalizing tendencies of modern western scholarship towards more traditional understandings of the lived experience of place, emphasizing the importance of the local context.

In practice, much of this scholarship involves creating maps — an act that is not without controversy.  Maps are conventional representations of space that come laden with the embedded cultural worldviews of their makers.  Maps are also highly simplified documents that often paper over contested or fuzzy boundaries with firm lines; it is hard to express ambiguity with maps, but it is very easy to lie with them.  The familiarity of widespread tools like Google Maps and Google Earth might fool us into thinking these are unproblematic representations of space, but it must be remembered that all maps contain embedded assumptions and cannot be taken at face value. Maps produced in the course of humanities scholarship are not just illustrations but arguments, and they must be read with the same level of critical analysis that you would apply to articles or monographs.

(For more concrete suggestions along these lines, see Humanizing Maps: An Interview with Johanna Drucker.)


Example 1

One area of historical research that saw an early adoption of GIS is economic land use.  A good example is Michael McCormick’s book on the Origins of the European Economywhich layered many different types of evidence against each other in a GIS to argue for a much earlier origin to Europe’s medieval economy than had been accepted previously.  McCormick has since made his database publicly available and continues to add to it with collaborators at Harvard, as the Digital Atlas of Roman and Medieval Civilization.

Screen Shot 2015-02-17 at 4.35.27 AM

The DARMC provides a rich resource and a good introduction to the potential of GIS to reveal patterns and connections through the spatial layering of disparate datasets.  It also offers a good orientation to the basic layout of most GIS systems, with a map view window on the right and a list of layers on the left that can be turned on and off.

  • Explore the DARMC.
    • What layers have been included?
    • What patterns show up when you juxtapose cultural, environmental and economic data in this way?
    • What connections do you see?
  • Also take the opportunity to explore the measurement tools at the top of the window to interrogate the spatial  attributes of the data.

Example 2

The quantitative data compiled in projects like the DARMC can help address many historical problems, but they don’t necessarily answer more qualitative research questions concerned with the lived experience of the past.  For this objective, we must move beyond birds-eye-view 2D maps of spatial distributions and attempt to visualize particular places at particular moments in time.  Such “geovisualization,”  the digital reconstruction of past landscapes, is another booming area of scholarship that allows us to virtually experience a place as it might have been, and also has the potential to answer important scholarly questions.

Screen Shot 2015-02-17 at 5.05.37 AMAnne Kelly Knowles’ digital reconstruction of the Battle of Gettysburg is an excellent example of this potential that uses a combination of digitized information from historical maps, documentary accounts and environmental data on the physical geography of the battlefield to answer the question of what the generals could see during the battle and how those sightlines influenced their decision making.

  • Read the brief introductory article at Smithsonian magazine and then explore the “story map” in detail.
    • How does the map combine geographic and temporal information?
    • Does it effectively give you a sense of the experience of being on the battlefield?
    • What does this reconstruction offer that more traditional publications could not?
    • What could be improved in the representation?

 


Group Exercise: The Varieties of Maps

(Exercise borrowed from Lincoln Mullen)

The next step is to become familiar with as wide a variety of maps as possible, including digital maps and analog, maps that have been made by scholars and maps that have not. Below is a list of online mapping projects.

In a group, pick three projects from the list to explore and compare. Your aim is to gain familiarity with projects involving maps and mapmaking, both by scholars and on the web generally.

As you look through these projects, consider the following questions or prompts.

  • Create a taxonomy of maps. What categories do these maps fit into? You might consider the purposes of the maps, their audience, their interfaces, among other axes of comparison.
  • What is the grammar of mapping? In other words, what are the typical symbols that mapmakers use, and how are they can they be put in relation to one another?
  • Which maps stood out to you as especially good or clear? Why?
  • Which maps were the worst? What made them bad?
  • How do scholarly maps differ from non-scholarly maps?
  • What kind of data is amenable to mapping? What kinds of topics
  • What accompanies maps? Who controls their interpretation? What is their role in making an argument?
  • How do recent web maps compare to maps made online in the past few years? How can maps be made sustainable?
  • Which of these maps are in your discipline? Which maps might be helpful models for your discipline?

 


Exercise (Georeferencing)

In order to reconstruct past landscapes like the Gettysburg battlefield, the first step is often digitizing the data recorded in a historic map by georeferencing (or georectifying) that image — that is, aligning the historical map or image with its location on the earth in a known coordinate system.  There are many ways to do this, but we will start with a cloud based solution requiring no complex software.

The David Rumsey Map Collection is a vast archive of scanned historic maps, mostly covering North and South America.  They have enabled a  crowd sourcing technique to get the public to help georeference these images for use in GIS applications, but the David Rumsey Georeferencer is very buggy and not very accurate.

Instead we will use the MapWarper online tool to rectify an historic map from an online collection of scanned images.

MapWarper.net screen shot

  • Go to Boston Public Library’s Norman B. Leventhal Map Center
    • Search for and download a historic map that covers an area of interest
  • Then follow these instructions from Lincoln Mullen to Georectify a map with MapWarper
    • Use their tool to set control points (at least 5 are recommended), clip the map area, and rectify the map
    • When you are finished, you will see the map overlaid on a basemap of the world.
  • You can download your newly rectified map as a KML file by going to the Export tab

Exercise (Digitizing)

Now that you have coordinates for your image, you can bring it into a GIS program, align it with other spatially-aware data, and digitize the information by creating vector geometry from it.  We’re going to do that in Google Earth as a first pass, since it is free, widely available and often people’s first introduction to using a GIS.

  • Open Google Earth and the newly rectified map by choosing File > Open from the menu and navigating to your downloaded kml file.
  • Double-clicking the file should launch Google Earth and show you the map aligned over the modern satellite imagery.

Screen Shot 2015-02-17 at 5.47.18 AM

  • Now use the Add PlacemarkAdd Polygon, and Add Path tools in the top menu to digitize features from your georeferenced map.
  • For instance you could pinpoint the old courthouse (a placemark, or point), trace the old shoreline (a path, or line feature), or trace the outline of a neighborhood (a polygon).
    • As you create features you can add metadata, change the symbols, and change the location of the camera to save alongside the feature in the Get Info window.
  • Finally you can right click your newly created features and save them as KML or KMZ files (a zipped version of KML) for use in other programs.

 


Resources

Lincoln Mullen of the Center for New Media and History at George Mason University has developed a fantastic resource for getting started with mapping for the humanities.

The Spatial Humanties Workshop site he developed will give you a detailed introduction to the different types of maps you might want to make as a digital humanist, the software and libraries that are out there to use, and most importantly the academic issues and theoretical questions that are raised by mapping humanities data in a digital space.