What is Web GIS...or any GIS?
Table of Contents
Terms: geographic information, geographic information system, layer, feature, operational layer, basemap, web, Web GIS
Web Maps in Demand
Something started happening in the late 2000s while doing IT in the geography department at Louisiana State University. It was becoming common to get questions about putting maps and data online. Faculty, students, local businesses, and state agencies wanted guidance on how to build interactive maps where their audience could zoom, pan, click features, and access source data. By that point in history, people were getting familiar with Google Maps (launched 2005) or similar products and had a clear vision of what their online maps could be. For the people asking me for help, however, it was less clear exactly how to put all the pieces of the technological puzzle together to accomplish their vision. Therefore, I was pulled into the world of “web GIS”, learning the software and techniques for mapping and sharing data online through websites, desktop applications, and mobile apps.
Online maps are in no less demand today, creating roles in organizations for people who understand web GIS. This course, beginning with this lesson, strives to introduce web GIS with a balance of doing and learning, translating into skills and knowledge to work with and understand web GIS now and in the future for research, commerce, government, personal interest, and civic duty.
GIS
The term “web GIS” needs further explanation, but first let us define GIS and geographic information.
Any type of information tied to a location on Earth can be considered geographic information (or similar terms: spatial data, geospatial data, location information). The border of a country is geographic information. Election results by precinct can be geographic information. Social media posts tagged at a restaurant location are geographic information.
Example: Information
| Hospital | Beds Available | Beds Total |
|---|---|---|
| Anytown General | 21 | 94 |
| Jackson Memorial | 35 | 74 |
Example: Geographic Information
| Hospital | Beds Available | Beds Total | Latitude | Longitude |
|---|---|---|---|---|
| Anytown General | 21 | 94 | 29.9241 | -90.3711 |
| Jackson Memorial | 35 | 74 | 30.0246 | -90.2721 |
A geographic information system (GIS) encompasses software and devices used to map, query, analyze, and manage location-based information. GIS software can display geographic information on a map on your screen, and also perform spatial calculations like finding all hospitals in New Orleans within one mile of an interstate highway.
The software can do this because of coordinate systems, like latitude and longitude, which allow datasets to be placed at numerically identifiable locations on Earth’s surface. Computers understand numbers, and GIS software in particular understands coordinate systems. GIS can do the math to calculate the distance between points, for example, or more complex geometry. Ultimately, GIS allows us to analyze geographic information and visualize it on maps to reveal patterns and relationships among things and phenomena on Earth. It helps us answer not just “where” but “why”.
Web GIS
The web, or World Wide Web (WWW), is a system of linked resouces on the Internet, including documents, images, and other media, accessed by a unique address and a standard communication protocol (HTTP, HTTPS).
GIS grew in popularity as a desktop application, but like other software it has evolved to take advantage of the Internet so that geographic information is not just a file saved on your computer, but a web resource similar to a webpage viewed in a browser or mobile app, shared with potentially millions of viewers.
The transmission of geographic information over the Internet is a fundamental aspect of web GIS, requiring certain techniques and considerations not typical of traditional GIS. These special requirements gave rise to a new field of expertise. To give it a simple definition for the purposes of this course, web GIS is any web-based system used to analyze, visualize, share, or organize geographic information. Typically, this means a website or mobile app displaying an interactive map including data layers, a basemap, and tools for using the map, but as we will see in this course, web GIS is much more than just maps and websites. We will look at how geographic information is moved around the world via the web.
To see some examples of web GIS applications in action, look through these websites:
- Google Earth
- Louisiana 2016 flood imagery
- Local weather radar
- Story map about global wildfires
- Video game map
- Large Orion Nebula image - not a map but uses web GIS techniques
Hands-on exercise
Before any further discussion of web GIS, this first lesson will end with a hands-on exercise. This will give you a concrete example to think back on when we discuss web GIS concepts in future lessons. For this exercise, we will use ArcGIS Online (arcgis.com), a website and family of apps geared toward making and sharing maps online. Hopefully, getting some quick experience with ArcGIS Online will give you a tangible answer to the question posed at the beginning of this lesson, “What is web GIS?”.
In the exercise, we will use ArcGIS Online Map Viewer to create a map.
ArcGIS Online Map Viewer lets you drag and drop certain files from your computer, such as a spreadsheet with place names and latitude/longitude coordinates, to load data to the map as layers. You can also add layers that are already hosted on ArcGIS Online, including authoritative layers from Esri or layers uploaded by other users.
Maps made in Map Viewer can be saved to ArcGIS Online and accessed from your ArcGIS Online Content page. The Content section of ArcGIS Online lets you manage the layers, maps, apps, images, and files you create or upload. Content items will get a URL that can be shared with your audience, the people you designed your map for. If you make your maps and data public, then they can be used in other people’s apps and maps on ArcGIS Online or elsewhere.
To complete this introduction to web GIS, let us begin making a webpage with a map on it (for simplicity, it will be called an “app” in ArcGIS Online vocabulary). Go to Assignments and proceed to Assignment 1, which follows Esri’s “Get Started with ArcGIS Online” tutorial.
After the tutorial, move on to Lesson 2 to go more in-depth into the “Web” and “GIS”.
Conclusion
This short lesson is just the beginning of an introduction to web GIS, meant for students who are unfamiliar with geographic information systems.
Web GIS exists due to the demand for online maps that are interactive and data-driven. Web maps have become familiar to us thanks to apps like Google Maps, but how they work and how to build one yourself is less familiar. This course aims to familiarize you with a range of topics that will help you understand the technology behind today’s web maps.
As you follow the tutorial in Assignment 1, keep in mind that we have not yet started the background lessons about the web and GIS in general, so it is alright if you are not familiar with all the terms used in the tutorial. We will get caught up on that later. For now, just follow along and make a map.
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