In this chapter, we learned how to obtain and transform geographic datasets using open source tools. We learned how to use and interpret two popular formats for mapping information for the Web, GeoJSON, and TopoJSON.

We also learned how to create simple charts based on SVG, rendering the geographic features as svg paths. We created a choropleth map using the Mercator projection and used TopoJSON to obtain information about topology, allowing us to identify neighbors and frontiers between countries.

Finally, we learned how to use Mapbox and D3 to create data visualizations for applications that require street-level detail.

In the next chapter, we will learn how to use other projections to create 3D-like views of our maps and how to project raster images in our maps.