Path Analysis with Vector Data Using QGIS

Introduction

QGIS is an application that is used for GIS (Geographic Information Systems) purposes that is Free and Open Source Software (FOSS). This software is user friendly. It runs on Linux, Unix, Windows, Mac OSX and Android. QGIS supports a variety of raster, vector and database formats and functions. The latest release is 3.10. It provides a continuous growing number of capabilities. It is provided by core functions and plugins. With QGIS, the user can manage, edit, conduct data analysis, visualize and create maps.

Figure 1. QGIS

This tutorial will guide the user through the process of downloading data, adding it to QGIS and conducting the analysis to find sections on a trail that connect to other path networks. In this tutorial, we will combine a variety of path networks and will find ways to access the main trail through these networks. The goal is to find ways to access the main trail from different areas within the city. This type of analysis can be used for any type of path analysis. We will use the Rideau Trail as the main path that we are analyzing. The other paths that we will be using to access the Rideau Trail are city roads, cycling routes, paths and parks. The data that is used here are all open sourced data.

Objective

We will be conducting an analysis of vector data. To access the main trail, we will need to find which lines intersect with the main trail. This process will allow us to find which paths or roads within Ottawa intersect with the main trail. These intersections will show how we can access the main path from different sections of the city.

The Rideau Trail is a hiking trail that links Ottawa to Kingston, it is 387 km long. The Rideau Trail Association maintains the trail so others can use it. They also provide information so others can use the trail. Once we have conducted our analysis, we will cross reference our information with maps provided by the Rideau Trail Association. The map keys will help us identify which maps we will need; to view the area in more detail.

Data

The type of data that we will be using are Keyhole Markup Language (KML) and shapefiles. We will be using vector data for this analysis.

Process

Please download the data from the references section before starting the project.

Open QGIS 3.10.

Open a new project and give it a name.

Add the data that will be used. It will be unorganized. It is recommended that you make changes to the layers, so it can be viewed more easily. You can turn off the map keys layer. It will be used for a later purpose, to cross-reference with other maps.

We will now conduct the path analysis of intersections to the main trail. Click the tab Vector/Analysis Tools/Line intersections...

A window will open. Select the input layer accordingly. The intersect layer will be the main trail. This process will be repeated with the other line layers for the input layer. Click run.

Once the multiple analyses are completed, change the symbols for easier viewing. you will now be able to see where various lines intersect with the main trail. The line intersections tool can be used to identify any paired combination of lines.

Cross-Referencing With Other Maps

Please turn on the map keys layer and open the link Rideau Trail in the reference section. We will now cross-reference our information with maps provided by the Rideau Trail Association.

Select Identify Features. Go to an area of interest in which intersections have been identified. Slect the map key on the map, it will identify the map key that will be required from the Rideau Trail Association.

Select the required map from the Rideau Trail Association.

View in Google Earth Pro

Since the data is KML, it can be viewed in Google Earth Pro.

References

KML Data

Cycling Network: https://open.ottawa.ca/datasets/cycling-network

Park Paths: https://open.ottawa.ca/datasets/park-paths

Road_Centrelines: https://open.ottawa.ca/datasets/road-centrelines

Rideau Trail https://www.rideautrail.org/discover-the-trail/maps/

Shapefile of Ottawa

Ottawa Neighbourhood Study (ONS) - Neighbourhood Boundaries Gen 2: https://open.ottawa.ca/datasets/ottawa-neighbourhood-study-ons-neighbourhood-boundaries-gen-2