Qgis Guide Pdf

[Karmen Mcarthun]

QGIShas a lot of documentation. All of the core documentation (user manual, developer handbooks etc.) is available in English. Some documents such as the user guide are also available in other languages.

Standalone installers include everything QGIS needs in a single download. Once you have the installer, no internet is required to complete the installation. When a new release is available, you need to download the complete installer again in order to upgrade. For beginners, the standlone installer is probably the easiest way to install QGIS:

The weekly snapshots of the nightly qgis-dev package of OSGeo4W are for users that cannot use OSGeo4W (see below) for some reason or just prefer standalone installers. In the feature freeze phase, theset also act as release candidate installers.

More advanced QGIS users should use OSGeo4W packages. This installer makes it possible to install several versions of QGIS in parallel and also to do much more efficient updates as only changed components are downloaded and installed with each new release.

The OSGeo4W repository contains a lot of software from OSGeo projects. QGIS and all dependencies are included, along with Python, GRASS, GDAL, etc. The installer is able to install from internet or just download all needed packages beforehand. The downloaded files are kept in a local directory for future installations and could also be used to install offline.

The packages listed in the above table only install the necessary dependencies needed to run QGIS. Corresponding to those packages there are also meta packages with the suffix -full-free and -full. The -full-free contains additional optional dependencies that some popular (not included in the default QGIS install) plugins use. The -full includes everything from -full-free and also adds proprietary extensions like Oracle drivers, ECW and MrSID.

In the section following this one, you will find ALL possible options to install different versions of QGIS in different versions of Debian/Ubuntu. If you have problems, verify whether your distribution is still supported as the repositories also contain older unsupported distributions with the last QGIS version that was supported. Be aware that those might have meanwhile ceased to work.

For Ubuntu we also used to have extra packages in a separate repository that are based on ubuntugis, which held more up-to-date versions of other GIS packages than Ubuntu itself for LTS versions. If you want those you also need to include ubuntugis-unstable ppa in your /etc/apt/sources.list.d/qgis.list file (see ubuntugis documentation).

The release packages are only produced once, shortly after a new version has been released. As unstable, not yet released debian versions (testing) and ubuntugis-unstable can have library changes the packages might sooner or later be broken for these targets, when the development in debian, ubuntu or ubuntugis-unstable moves on and their packages used as dependencies in QGIS change. In that event you can either:

switch to a nightly repository (available for the two release branches and master) whose packages are rebuild on regular basis and will also pickup the updated dependencies automatically or

Because of the atomic nature of NixOS packages, you need to override the package if you want extra python packages to be available to QGIS. For example to run QGIS with numpy, geopandas and rasterio python libraries you can do:

The package management system MacPorts offers both the latest release version (port qgis3) and the long term version (port qgis3-ltr). This will install QGIS with native architecture, Intel x86_64 or Apple ARM. Main software dependencies such as GDAL, PDAL and GRASS GIS are usually the latest version available.

QGIS testing packages are provided for some platforms in addition to the QGIS stable version. QGIS testing contains unreleased software that is currently being worked on. They are only provided for testing purposes to early adopters to check if bugs have been resolved and that no new bugs have been introduced. Although we carefully try to avoid breakages, it may at any given time not work, or may do bad things to your data. Take care. You have been warned!

This is an introductory course that covers QGIS from the very basics.You will learn to use QGIS for mapping, spatial data processing, andspatial analysis. This class is ideal for participants with a basicknowledge of GIS and who want to learn how to use QGIS to carry outeveryday GIS tasks.

The exercises and challenges in this course use a variety ofdatasets. All the required datasets are supplied in theintroduction_to_qgis.zip file. Unzip this file to adirectory - preferably to the/Downloads/introduction_to_qgis/folder.

This section is designed to help you get familiar with the basicworkflow of importing data layers, applying symbology, adding labels,and designing layouts for maps. We will take a text file containinghistorical records of earthquakes and turn it into an informativevisualization like the one below.

QGIS has many rich cartography features. One of my favorites iscalled Live Layer Effects. This allows you to add effects suchas Outer Glow, Drop Shadow, etc., to each symbol. Thistakes your symbology to the next level and helps highlight certainfeatures. Select the large_earthquakes layer and open theLayer Styling Panel. Expand the Layer Renderingsection and enable Draw effects. Click the Customizeeffects button and add a drop shadow effect to the layer.

Labels are a useful way to convey additional information for anyfeatures. Labels are associated with each feature and can be configuredto show information from the attributes. We will now add labels to eachof the large earthquake points to show the name of the location as wellas the deaths caused due to that earthquake.

Tip: If a label disappears after moving it, it means that it has beenplaced at a position that cannot be displayed on the map withoutcolliding with other labels. You can see the unplaced labels by clickingthe Toggle Display of Unplaced Labels button on the LabelToolbar. Once the label is shown, you can move it to another spotwhere it can be displayed.

The numbers displayed in the labels can be hard to read since theyare not formatted. We can make them readable by adding athousand-separator. So a number such as 227899 is displayed as227,899 and a number like 5749 as 5,749.Update the expression for the labels, so the numbers are formatted. Toachieve this, you can use the format_number() function inthe QGIS expression editor.

Hint: The PDF Export Options dialog has an optionSimplify geometries to reduce output file size at the bottom.While useful, this can have unexpected effect on the output. Un-check itwhile doing the export.

In this section, we will learn basic data processing andvisualization techniques. We will use geographic boundaries andpopulation count data for the City of New York and create a populationdensity map. This requires doing a table join and using a graduatedsymbology to create a choropleth map.

Your task is to design a map of Population Density of New YorkCity in QGIS Print Layout. You can take the choropleth map createdin the previous section 2.2 Createa Choropleth Map and design a map in the Print Layout. In additionto the rendered vector layer, the map must have at least the followingelements:

Georeferencing is the process of assigning real-world coordinates toeach pixel of the raster. This is an important step in preparing yourdata for further analysis. Many projects, particularly machine learningprojects - need continuous historic records to build a model. Many ofthe older datasets may come in form of scanned maps or aerial photosthat needs to be georeferenced. Similarly, some organizations may onlyshare a PDF or a static map image of the dataset which will need to beconverted into a GIS-ready format using georeferencing process.

Georeferencing process involves collecting GCPs (Ground ControlPoints) or Tie-Points. These GCPs are easily identifiable features inthe image or map whose real-world coordinates are obtained fromfield-survey using a GPS device or identified from already georeferencedsources within a GIS.

You will see a warning against using contributed services. Some ofthese services may have restrictions on their usage and/or attributionrequirement that you need to follow. Please review them before usingthem in your project.

In this exercise we used the Polynomial 2 technique.For datasets that require more aggressive transformation, you can usethe Thin PlateSpline algorithm. This method is also known as RubberSheeting. Change the transformation setting to use ThinPlate Split and run the georeferencer again. Compare the outputwith the previous result.

Many GIS tasks require editing existing data layers or creating newdatasets. Often a large amount of GIS time is spent digitizing rasterdata to create vector layers that you use in your analysis. Many machinelearning projects also require creating a labeled dataset that needs tobe made by digitizing features from satellite imagery or historicalmaps. QGIS has powerful on-screen digitizing and editing capabilitiesthat we will explore in this tutorial.

In this exercise, you will create a vector layer of historic lakes inthe city of Bangalore, India. This city has experienced urbanization ata rapid pace. Due to this, many water bodies have been lost. We will usethe georeferenced scanned map from the previous exercise to digitizepolygons for all the water bodies in 1924 and label their currentstatus. Finally, we will create a vector layer and assign attributes tothem, indicating whether they are healthy, lost, or partially lost.

The fid column contains auto-increment unique id foreach feature.The GeoPackage format requires this integer field tomaintain data integrity. Manually overriding this id to a differentvalue can cause data corruption. Edit the attribute form for thefid field so that it is not user-editable.

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