Book Image

QGIS Blueprints

By : Ben Mearns
Book Image

QGIS Blueprints

By: Ben Mearns

Overview of this book

Table of Contents (14 chapters)
QGIS Blueprints
About the Author
About the Reviewers

Chapter 4. Finding the Best Way to Get There

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...