Introduction to Web Mapping
Last updated: 2020-06-24 13:45:21
0.1 What is web mapping?
A web map is an interactive display of geographic information, in the form of a web page, that you can use to tell stories and answer questions. In the past, most digital geographic information was confined to specialized software on desktop PCs and could not be easily shared. With the advent of web mapping, geographical information can be shared, visualized, and edited in the browser. The most important advantage to this is accessibility: a web map, just like any website, can be reached by anyone from any device that has an internet browser and an internet connection.
Web maps are interactive. The term interactive implies that the viewer can interact with the map. This can mean selecting different map data layers or features to view, zooming into a particular part of the map that you are interested in, inspecting feature properties, editing existing content, or submitting new content, and so on.
Web maps are also said to be powered by the web, rather than just digital maps on the web. This means that the map is usually not self-contained; in other words, it depends on the internet. At least some of the content displayed on a web maps is usually loaded from other locations on the web, such as a tile server (Section 188.8.131.52).
|Visualization and journalism||Global Migration|
|Real-time information||Earth Weather||Figure 0.1|
|Real-Time Transport Location|
|Real-Time Flight Locations|
|Stuff in Space|
|Global Forest Watch|
|Israel 23rd Elections|
|Catalog and search||Earth Data Search|
|Computational tools||Google Maps|
|geojson.io||see Section 7.4.1|
|mapshaper||see Section 7.4.2|
|Reporting and collaboration||OpenStreetMap||see Section 13.2|
The availability of code-free, graphical interfaces for making sophisticated web maps remains an ongoing goal for the web-mapping community. Several platforms now provide straightforward interactive interfaces for building and publishing web maps and web-mapping applications, such as:
A more customizable, programmatic approach for building web maps is available through scripting languages such as R and Python. Both languages have libraries that give the ability to build web maps, using few lines of code and incorporating data from the user environment:
0.4 Learning objectives
By the end of this book, you will be able to:
- Build and publish basic websites and web maps
- Connect you web map to a database to display large amounts of data
- Include client-side geoprocessing functionality in your web map
- Gain an understanding on how the web works, and a starting point for learning more
Throughout the book, we are going to use the following software components, which are freely available on the web:
- A plain text editor, such as:
- A modern web browser2:
- Web developer tools (built into Chrome and Firefox)
- A local web server (built into Python, other options are available)
While emphasizing open-source solutions, we will also demonstrate the commercial services GitHub and CARTO, chosen for their simplicity. Free and open-source alternatives giving the same functionality will be mentioned for those willing to explore more complicated options. Several datasets from the book are also demonstrated using the QGIS software (Figures 8.3, 9.3), but it is not essential to be familiar with QGIS, or any other geographic information system (GIS) software, to follow the material.
0.6 Background knowledge
The book can be used as primary text for a web-mapping course in geography departments, or by anyone who is interested in the topic. Each of the thirteen chapters is designed to be covered in a three-hour lecture, or through self-study. Short questions and exercises are given throughout the chapters to demonstrate the material from different angles and facilitate understanding. There are also concluding exercises with complete solutions (Appendix C) at the end of Chapters 3–4 and 6–12.
Familiarity with basic concepts of geographic data and GIS (coordinate systems, projections, spatial layer file formats, etc.) is necessary for deeper understanding of some of the topics in the book. Readers who are not familiar with GIS can skip the theoretic considerations and still follow the material from the technical point of view.
0.7 Online version
The online version of this book is freely available, with agreement from the publisher, at the following addresses:
In addition to the content of the printed version, the online version includes live versions and downloadable code for all ninety-plus complete examples (Appendix B) and exercise solutions (Appendix C), as well as an additional appendix with instructions for setting up an SQL API (see Section 9.2.2).
I thank the creators and contributors of the open-source tools used in this book, namely Leaflet, Turf.js, Leaflet.heat, and Leaflet.draw (Table 0.2). Vladimir Agafonkin, the creator of the Leaflet web-mapping library, deserves special mention here. Leaflet took open-source web mapping to a new level: for me to write this book, and for readers to enter the field of web mapping, would have been much more difficult without Leaflet. I am also grateful to Yihui Xie, whose
bookdown (Xie 2018, 2016) R package (R Core Team 2018) greatly facilitated the technical process of writing the book.
Figure 6.1 was prepared using R packages
sf (Pebesma 2018) and
rworldmap (South 2011). Figure 7.1 and the images inside Tables 7.2–7.6 were also prepared using package
sf. Figure 8.4 was prepared using R package
RColorBrewer (Neuwirth 2014). Figures 8.3 and 9.3 were prepared using QGIS (QGIS Development Team 2018). The sample database shown in Figure 9.1 was prepared using data from R package
nycflights13 (Wickham 2018). Figures 6.2 and 6.3 display images of OpenStreetMap tiles (© OpenStreetMap contributors).
I would like to thank Rob Calver and Lara Spieker from CRC Press for working with me and supporting this project, starting from a talk with Rob at a conference in Brussels in summer 2017, going through project initiation, the professional review process, and up to finalizing the manuscript and bringing it to press. I also thank Annie Sophia, Vaishali Singh and Jyotsna Jangra for the professional proofreading and production of the book. Shashi Kumar and John Kimmel from CRC are acknowledged for their assistance in technical issues.
Several figures in the book include icons from external sources: “computer,” “web page,” and “car” icons by Freepik, “folder” and “database” icons by Smashicons, “gears” icon by Good Ware, from https://www.flaticon.com/, licensed by CC 3.0 BY.
Neuwirth, Erich. 2014. RColorBrewer: ColorBrewer Palettes. https://CRAN.R-project.org/package=RColorBrewer.
Pebesma, Edzer. 2018. “Simple Features for R: Standardized Support for Spatial Vector Data.” The R Journal 10 (1): 439–46. https://journal.r-project.org/archive/2018/RJ-2018-009/index.html.
QGIS Development Team. 2018. QGIS Geographic Information System. Open Source Geospatial Foundation. http://qgis.osgeo.org.
R Core Team. 2018. R: A Language and Environment for Statistical Computing. Vienna, Austria: R Foundation for Statistical Computing. https://www.R-project.org/.
South, Andy. 2011. “rworldmap: A New R package for Mapping Global Data.” The R Journal 3 (1): 35–43. http://journal.r-project.org/archive/2011-1/RJournal_2011-1_South.pdf.
Wickham, Hadley. 2018. Nycflights13: Flights That Departed Nyc in 2013. https://CRAN.R-project.org/package=nycflights13.
Xie, Yihui. 2016. Bookdown: Authoring Books and Technical Documents with R Markdown. Boca Raton, FL, USA: Chapman; Hall/CRC. https://github.com/rstudio/bookdown.
Xie, Yihui. 2018. Bookdown: Authoring Books and Technical Documents with R Markdown. https://github.com/rstudio/bookdown.
Based on the StackOverflow survey for 2018 (https://stackoverflow.blog/2018/05/30/public-data-release-of-stack-overflows-2018-developer-survey/).↩
There is no clear definition of the term modern web browser, but older versions of Internet Explorer are, arguably, not considered as modern browsers and thus not recommended to illustrate web development (https://teamtreehouse.com/community/what-is-a-modern-browser).↩