An Absolute Beginner's Guide to QGIS 3

GeoDelta Labs・2 minutes read

A tutorial on using QGIS as an open-source alternative to Esri's ArcGIS, covering topics like installing the software, working with vector and raster data, and creating publishable quality maps. The tutorial emphasizes the importance of understanding panels, toolbars, and tool options for efficient work with vector data in QGIS, providing a comprehensive guide for beginners.

Insights

  • QGIS is a cost-effective alternative to ArcGIS that offers similar functionalities, making it accessible for beginners through tutorials covering installation, data manipulation, and map creation.
  • The tutorial emphasizes the importance of understanding attributes, digitizing shapes accurately, and enhancing maps with features like legends and scale bars, focusing on creating visually appealing and informative geospatial representations.

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Recent questions

  • What is QGIS?

    Open-source alternative to ArcGIS for mapping.

  • How to install QGIS?

    Visit www.qgis.org and follow installation instructions.

  • What are shapefiles in QGIS?

    Geographic data files for visualization and manipulation.

  • How to create polygon shapefiles in QGIS?

    Digitize shapes, define attributes, and save edits.

  • How to enhance map quality in QGIS?

    Use print layout feature for presentation.

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Summary

00:00

"QGIS Tutorial: Open-Source Alternative for Beginners"

  • QGIS is presented as an open-source alternative to Esri's ArcGIS, offering similar functionalities without requiring a costly subscription.
  • The tutorial aims to provide an introductory guide to QGIS for beginners, highlighting its flexibility and capabilities.
  • The major topics covered in the tutorial include installing QGIS, navigating the interface, working with vector and raster data, installing plugins like OpenStreetMap, and creating publishable quality maps.
  • To download QGIS, visit the website www.qgis.org, select the appropriate version based on your operating system, and follow the installation process.
  • The tutorial demonstrates how to add shapefiles to QGIS by dragging and dropping them into the interface, allowing users to visualize and manipulate geographic data.
  • Users can customize the appearance of shapefiles by changing colors, markers, and sizes through the properties and symbology options.
  • Accessing the attributes table of a layer provides detailed information about the data associated with each point or polygon in the shapefile.
  • The tutorial introduces essential panels in QGIS, such as the browser panel for data navigation, the layers panel for managing imported layers, and the processing toolbox for geoprocessing tasks.
  • Toolbars in QGIS, like the data source manager toolbar, can be activated or deactivated based on the user's preferences to streamline workflow.
  • Understanding the functionality of panels, toolbars, and tool options is crucial for efficiently working with vector data in QGIS.

13:57

Mapping Features and Functions in GIS Software

  • Shape files from various sources may contain corresponding attributes, such as hospital names and cities.
  • Clicking on attributes in the file highlights the corresponding points on the map.
  • Multiple attributes can be selected simultaneously by holding down the control key.
  • Deselecting all selected attributes can be done using the "deselect all features" button.
  • Attributes table displays ID numbers, descriptions, and locations like cities.
  • Importing a new shape file, like major roads, involves dragging and dropping it into the interface.
  • Zooming in and out can be done using the mouse wheel or the zoom in/out buttons.
  • Adjusting the appearance of lines in shape files can be done through properties and symbology settings.
  • Labels displaying names of hospitals can be added to the map by selecting the layer, going to properties, and choosing the name column.
  • Adding a base map, like an OpenStreetMap, can be achieved through the Quick Map Services plugin, enhancing geographical context.

28:23

Creating Polygon Shape Files for Water Bodies

  • To create polygon shape files for water bodies near Height Bark, go to Layer, create a new shapefile layer, name the file, and save it in the desired location.
  • Select the geometric type based on what you are digitizing - point for pinpointing, lines for roads, and polygons for areas like ponds.
  • Define attributes for the shapefile, such as adding a name attribute with a text data type and specifying the length of characters.
  • Include additional attributes like location and item number, selecting appropriate data types and lengths for each.
  • After setting attributes, proceed to digitize by toggling editing mode, selecting the add polygon feature, and drawing the shape on the map.
  • Add attributes for each digitized feature, ensuring accuracy in names, locations, and item numbers.
  • Save the edits to make them permanent and view the attributes in the attributes table.
  • Correct any errors in digitizing by toggling editing mode, selecting the attribute to modify, and adjusting the vertices as needed.
  • Check the accuracy of the digitized shapefile by adjusting the opacity to overlay it on the base map for comparison.
  • Save the shapefile, ensuring all necessary files are created, and understand the difference between vector data (shapefiles) and raster data (digital elevation models).

43:59

Raster Data: Functions, Features, and Visualization

  • Geospatial raster data is composed of individual pixels, each representing a specific area when zoomed in.
  • Land use or cover types can be accurately depicted using raster data due to the detailed distribution.
  • The tutorial focuses on basic functions with raster data, preparing users for advanced features exploration.
  • Changing the color distribution of a raster involves accessing properties, selecting symbology, and choosing color ramps.
  • By identifying pixels on a digital elevation model, users can determine precise elevation values.
  • Clipping a raster by a polygon boundary allows users to focus on specific areas of interest.
  • Contour lines can be extracted from the clipped raster using QGIS, with intervals set manually.
  • Contour lines can be labeled with elevation values for easy interpretation on the map.
  • Saving contour shapefiles permanently involves exporting them in formats like shapefile or KML for Google Earth.
  • Creating a visually appealing map can be done through QGIS's print layout feature, enhancing the presentation of data.

59:07

Creating High-Quality Maps for Publishing

  • To improve the map quality for publishing, start by adding a map item and drawing a rectangle on the mapping canvas to transfer geospatial data.
  • Adjust the map extent by selecting the drawn box, going to item properties, and interactively editing the map extent to move items and change the scale.
  • Use the scroll wheel or the scale value to zoom in or out on the map, ensuring precise adjustments.
  • Add a legend by selecting add legend, then customize it by removing unwanted items and adjusting decimal points for clarity.
  • Rename layers for a more presentable map, updating changes to reflect in the mapping canvas.
  • Enhance the map with a border, a north arrow, and a scale bar, adjusting their positions for optimal display.
  • Finally, add a title label to the map, adjust its alignment and font size, and consider adding a background like OpenStreetMap with reduced transparency for a polished finish.
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