Michael Dorman - Introduction to Web Mapping

Introduction to Web Mapping

Introduction to Web Mapping

Michael Dorman

CRC Press

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To my daughter Ariel,
who inspires me to explore new things

Contents

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 ().

Web maps are useful for various purposes, such as data visualization in journalism (and elsewhere), displaying real-time spatial data, powering spatial queries in online catalogs and search tools, providing computational tools, reporting, and collaborative mapping. Some examples of web maps used for different purposes are given in . All of these are built with JavaScript.

TABLE 0.1: Examples of web maps for different purposes

Purpose	Example	Notes
Visualization and journalism	Global Migration Ship Traffic Israel Municipalities NYC Planning
Real-time information	Earth Weather Real-Time Transport Location Real-Time Transport Location Stuff in Space Global Forest Watch
Catalog and search	Earth Data Search
Computational tools	Google Maps SunCalc geojson.io mapshaper Route Planner	see see
Reporting and collaboration	OpenStreetMap Falling Fruit

FIGURE 1: Real-time earth weather visualization on https://earth.nullschool.net

JavaScript is a programming language, primarily used to control interactive behavior in web pages. Alongside HTML and CSS, JavaScript is one of the three core technologies of the web. JavaScript is the only programming language that can run in the web browser, and it is used by 95% of websites. The importance of the internet thus makes JavaScript one of the most popular programming).

FIGURE 2: Programming language popularity, based on the StackOverflow survey for 2018

JavaScript and web development are huge topics. In this book, we are going to learn JavaScript from the specific point of view of web mapping.

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:

• CARTO Builder
• Mapboxs Studio
• ESRIs Configurable Apps
• qgis2web Plugin for QGIS

A more customizable, programmatic approach for building web maps is available through scripting languages such as RindexR (language)/index and PythonindexPython (language)/index. Both languages have libraries that give the ability to build web maps, using few lines of code and incorporating data from the user environment:

• leaflet (R packages)
• folium (Python library)

All of the above eventually build HTML, CSS, and JavaScript code, with varying degrees of flexibility and customization.

Nevertheless, proficiency in the fundamental web technologies HTML, CSS, and JavaScript eventually allows web cartographers to control all low-level properties of the web map they are building. That way, the user experience of web maps can be enhanced and customized beyond what is provided by either of the above indirect, or high-level, approaches. For example, the Leaflet web mapping JavaScript library has a wide range of plugins and extensions, mostly unavailable in external tools and libraries unless using it directly, through JavaScript coding.

By the end of this book, you will be able to: