Create, edit and use custom mapping data
Linux Format|October 2021
If you like Google Maps you’re going to love QGIS. Mike Bedford shows you how to get started and introduces some of its functionality.
Mike Bedford

Back in 1962, archaeologists in the Czech Republic discovered a mammoth’s tusk that has been engraved with a geometrical design. The pattern was subsequently identified as representing the hills, rivers, valleys and routes of the surrounding area. It was dated around 250,000 BC, making it probably the earliest map ever discovered.

In the library of Hereford Cathedral is the Mappa Mundi. Created around 1300, it’s the largest surviving medieval map of the world. The UK’s Ordnance Survey was set up in 1791 to help address the perceived risk arising from the Jacobite rising, and of invasion by France, and it went on to become one of the world’s foremost national mapping agencies. And 1999 saw California-based ESRI release its ArcGIS graphical information system, which would become the world’s most used GIS (geographic information system).

These few notable dates in the history of cartography illustrate 27,000 years of change and it’s clear that the rate of change has accelerated significantly in recent years. This isn’t surprising since digital technology has had the same effect on so many other areas, but it’s been suggested that a GIS is so different to its predecessors that it’s a totally new entity. Professionals point to support of multiple layers and an ability to carry out analyses of geographically based data as just some of the things you can do with a GIS but not with an ordinary map. And if you’re wondering where Google Maps fits in, while we’re not going to get embroiled in the debate over whether or not it’s a GIS, we would agree with the sentiment that a fully blown GIS is like Google Maps on steroids.

ESRI’s well-respected ArcGIS isn’t cheap at £1,192 per year, including VAT, for professional use. This reduces to £139 for non-commercial use, but that’s still a lot unless you have a fairly serious application. Our subject here, therefore, is the free open source QGIS which is widely used professionally and is considered to be on par with many professional GIS offerings.

We’re going to provide a hands-on introduction to using QGIS but we’re certainly not going to be looking at all its features, in fact we won’t come close. After all, if you can think of something you believe you ought to be able to do with mapping data, it’s a fair bet that QGIS can do it, either natively or via one of its many plug-ins. However, we trust that our tentative first steps will be enough to excite you about the possibilities of QGIS and start you off on your own voyage of discovery.

Orientate yourself

If your main experience with digital mapping has involved Google Maps, the first thing you’ll notice when you start up QGIS for the first time is that you don’t see a map at all. Instead, unless you open a project that someone else has produced, you’ll need to create a new project but, even having done that, you’ll be faced with a blank canvas to which you’ll need to add data as layers.

Usually you’ll want to start a project by adding a base map so, let’s see how to do that, but first create a new project at Project>New. Now, in the Browser panel at the top-left, find and expand the XYZ Tiles entry and double-click OpenStreetMap. This will add the open source OpenStreetMap as a new layer. The map will appear in the main window and you’ll also be able to see it listed in the Layers panel at the bottom-left.

Although OpenStreetMap is the only base map shown by default, there are lots of others you can use, and you might like to familiarise yourself with what’s on offer. You’ll have to search out the URLs yourself, but as an example, right-click XYZ Tiles in the Browser panel and select New connection… In the Connection Details dialog, enter https://tile.opentopomap. org/%7Bz%7D/%7Bx%7D/%7By%7D.png as the URL, give it a name such as OpenTopoMap and click OK.

OpenTopoMap will appear below OpenStreetMap under XYZ Tiles and, if you double-click it, OpenTopoMap will appear as a second layer. In fact, it’ll appear to have replaced OpenStreetMap in the main window, but that’s only because it’s the top-most layer: it appears above OpenStreetMap in the list, and it’s fully opaque. We’ll look at opacity later but, for now, note that you can swap to seeing the OpenStreetMap again by clicking the tick box next to OpenTopoMap so it’s not displayed, or by dragging OpenStreetMap to the top of the list.

This method of adding base maps isn’t limited to maps in the normal sense of the word. You can also add satellite or aerial imagery using the same method. To add Google imagery, for example, use https://mt1. google.com/vt/lyrs=s&x=%7Bx%7D&y=%7By%7D&z=%7Bz %7D as the URL.

Elevation data

So far, we’ve seen how to add various layers to a QGIS project, although all of those layers were essentially images of one type or another. But since a GIS is concerned with far more than just images, or maps if you prefer, let’s take a look at how other types of data can be added.

To start we’re going to add some elevation data, but first a few words on types and sources. The types you’ll mostly find are DSMs (digital surface models) and DTMs (digital terrain models). DSMs include objects such as trees, buildings and cars, as well as the actual ground, while in a DTM the former types of object are filtered out so it represents only the topography. In the UK, elevation data has been produced by the Environment Agency at a resolution of 1m or 2m, and is distributed freely online by DEFRA. Over the Pond, the USGS makes elevation data available for the US at resolutions ranging from 10m to 30m, but with the aim of migrating to 1m. They also provide Space Shuttlederived data for most of the world at 30m resolution. Commonly elevation data is provided as a GeoTIFF file, which is a geo-referenced variant of the familiar TIFF image format, although there are other formats, and QGIS supports most of them.

Once you’ve downloaded the elevation data it’s time to import it into a QGIS project, ideally one into which you’ve already added a base map. Select Add Layer from the Layers menu and then choose Add Raster Layer… In the dialog, select the elevation data file by clicking the three dots against Raster Dataset(s) and clicking Add.

Continue reading your story on the app

Continue reading your story in the magazine

MORE STORIES FROM LINUX FORMATView All

Pinhole photography with the HQ Camera

Interchangeable lenses enable us to experiment with that historical curiosity, the pinhole camera, Mike Bedford shows you how.

10+ mins read
Linux Format
October 2021

Linux Mint 20.2

Jonni Bidwell is running low on mint metaphors and time, but the promise of some budget mojito mix expedited this review.

6 mins read
Linux Format
October 2021

Griftlands

Management love a tough negotiation but not with the staff, so Sam Greer will be getting a quick visit from the LXF shock troops right about now…

5 mins read
Linux Format
October 2021

IT'S A VIRTUAL SERVERWORLD

From his caravan in a field in North Wales, David Rutland takes you on a touring holiday through the world of virtual private servers.

10+ mins read
Linux Format
October 2021

Going back to 8-bit with the Atari 800

Les Pounder goes back to a time before E.T. cartridges were buried in the desert and 48KB was considered lots of RAM.

10+ mins read
Linux Format
October 2021

CUSTOMISE MINT 2O!

Linux Mint is fantastic, but it’s also flexible, malleable and tweakable. Jonni Bidwell shows you how to truly make it your own.

10+ mins read
Linux Format
October 2021

Get better Steam and Proton gaming

Michael Reed looks at what it takes to run a large variety of games under Steam, including those designed to run on Windows.

10+ mins read
Linux Format
October 2021

Create, edit and use custom mapping data

If you like Google Maps you’re going to love QGIS. Mike Bedford shows you how to get started and introduces some of its functionality.

10+ mins read
Linux Format
October 2021

AMD Ryzen 7 5700G

The AMD APU makes a more-than-welcome return for Chris Szewczyk.

3 mins read
Linux Format
October 2021

BEST STRATEGY GAME - 0 A.D.

Version: 0.24 Web: https://play0ad.com

1 min read
Linux Format
September 2021
RELATED STORIES

OLED For Less

SONY’S NEW XR-65A80J OLED TV isn’t a member of the company’s Master Series—that designation belongs to its XR-A90J OLED models, which are spec’d to deliver higher brightness than the XR-A80J sets. And while we haven’t yet tested those pricier Sony OLEDs, the XR-65A80J is far from being a second-class citizen. Read on to find out why.

10+ mins read
Sound & Vision
October - November 2021

GOOGLE SAYS FLIGHT SEARCH TOOL CAN HELP YOU FLY ‘GREENER'

A basic search for flights will give an estimate of how many kilograms of carbon dioxide the flight will spew from start to finish.

2 mins read
Techlife News
October 09, 2021

GOOGLE IN COURT TO APPEAL EU'S 2018 ANDROID ANTITRUST CASE

Google headed to a top European Union court this week to appeal a record EU antitrust penalty imposed for stifling competition through the dominance of its Android operating system.

2 mins read
AppleMagazine
October 01, 2021

HOW TO DISAPPEAR COMPLETELY FROM THE INTERNET

It’s not just government spying; big-tech behemoths including Amazon, Google, Facebook, and Microsoft have collected huge amounts of people’s data in order to serve up targeted ads—and then, there’s the personal data that’s scooped up in all the breaches and hacks.

10+ mins read
PC Magazine
October 2021

AI THAT WORKS FOR EVERYONE

Timnit Gebru, Google’s former co-head of ethical AI research, on how to rethink and reform her field

3 mins read
Bloomberg Businessweek
September 27, 2021

GOOGLE TO SPEND $2.1 BILLION ON MANHATTAN CAMPUS ACQUISITION

Google is planning to buy New York City’s St. John’s Terminal for $2.1 billion, making it the anchor of its Hudson Square campus.

1 min read
AppleMagazine
September 24, 2021

Apple, Google Raise New Concerns by Yanking Russian App

Big Tech companies that operate around the globe have long promised to obey local laws and to protect civil rights while doing business.

5 mins read
Techlife News
September 25, 2021

Help, my teacher is a nightmare!

TEACHER GETTING YOU DOWN? HERE’S HOW TO HANDLE THE SITCH BEFORE THEY SQUASH YOUR FRESH FALL VIBE.

6 mins read
Girls' Life magazine
October/November 2021

SET AN AI TO MAKE AN AI

GOOGLE is already putting machine learning to work on improving itself

5 mins read
PC Gamer US Edition
November 2021

GOOGLE TO INVEST $1.2B IN GERMANY CLOUD COMPUTING PROGRAM

Google said that it is investing 1 billion euros ($1.2 billion) by 2030 to expand its cloud computing infrastructure in Germany and to increase the use of renewable energy.

1 min read
AppleMagazine
September 03, 2021