In this chapter, we will explore formal network-like geographic vector object relationships. Topological relationships are useful in many ways for geographical data management and analysis, but perhaps the most important application is optimal path finding. Specifically, you will learn how to make a few visualizations related to optimal paths: isochron polygons and accumulated traffic lines. With these visual elements as a background, we will incorporate social media feedback through Twitter in our web map application. The end result will be an application that communicates back and forth with the stakeholders about safe school routes.
In this chapter, we will cover the following topics:
Downloading OpenStreetMap data
Spatial queries
Installing Postgres/PostGIS/pgRouting
Building a topological network
DB Manager
Using the shortest path plugin to test the topology
Generating the costs to travel to a point for each road segment
Creating the isochron contours...