Book Image

QGIS:Becoming a GIS Power User

By : Ben Mearns, Alex Mandel, Alexander Bruy, Anita Graser, Víctor Olaya Ferrero
Book Image

QGIS:Becoming a GIS Power User

By: Ben Mearns, Alex Mandel, Alexander Bruy, Anita Graser, Víctor Olaya Ferrero

Overview of this book

The first module Learning QGIS, Third edition covers the installation and configuration of QGIS. You’ll become a master in data creation and editing, and creating great maps. By the end of this module, you’ll be able to extend QGIS with Python, getting in-depth with developing custom tools for the Processing Toolbox. The second module QGIS Blueprints gives you an overview of the application types and the technical aspects along with few examples from the digital humanities. After estimating unknown values using interpolation methods and demonstrating visualization and analytical techniques, the module ends by creating an editable and data-rich map for the discovery of community information. The third module QGIS 2 Cookbook covers data input and output with special instructions for trickier formats. Later, we dive into exploring data, data management, and preprocessing steps to cut your data to just the important areas. At the end of this module, you will dive into the methods for analyzing routes and networks, and learn how to take QGIS beyond the out-of-the-box features with plug-ins, customization, and add-on tools. This Learning Path combines some of the best that Packt has to offer in one complete, curated package. It includes content from the following Packt products: ? Learning QGIS, Third Edition by Anita Graser ? QGIS Blueprints by Ben Mearns ? QGIS 2 Cookbook by Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy
Table of Contents (6 chapters)

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...