QGIS | Digitizing map data, geometries and actions
> Objective
The students will learn how to convert physical and scanned geographical data into digital data
The section covers geometries
The section covers actions
> Index / Table of Contents
Introduction
Tutorial(s)
Digitizing map data
Create, edit and remove geometries
Snapping
Vector overlay tools
Other tools and methods related to geometries
Actions
QGIS installation
> Summary and Highlights
Introduction
Geographical data can be created by drawing geometries on scanned maps or images. The process of converting these data into a digital format is called digitizing. First, the section explains how to convert physical or scanned maps into digital ones. Then, the section covers how to work with geometries and how to deal with some problems that can be encountered while working with them. The last part addresses actions, which is something that happens when a feature is clicked.
Tutorial(s)
Digitizing map data
Physical or scanned maps can be converted into digital ones.
Digitize a raster topographic map to several vector layers Ujaval Gandhi: “Digitizing Map Data (QGIS3)”/”Kaartgegevens digitaliseren (QGIS3)” Language(s): English, Dutch Chapters: overview of the task, get the data, procedure EN: https://www.qgistutorials.com/en/docs/3/digitizing_basics.html NL: https://www.qgistutorials.com/nl/docs/3/digitizing_basics.html
Digitize a raster map image, using an example from TU Delft campus TOI-pedia: “Creating vector data” Language(s): English Chapters: introduction, procedure (basic digitising, digitising specific shapes) http://wiki.bk.tudelft.nl/toi-pedia/Creating_vector_data
Digitize a raster layer QGIS Training manual: “Creating a New Vector Dataset” Language(s): English Chapters: follow along: the layer creation dialog, follow along: data sources, try yourself: digitizing polygons, follow along: using vertex editor table, try yourself: digitizing lines, in conclusion, what’s next https://docs.qgis.org/3.10/en/docs/training_manual/create_vector_data/create_new_vector.html
Advanced digitizing tools: drawing circles and rectangles Stefan van der Spek “MScU QGIS Q1 Advanced Digitizing” Language(s): English Time: 4min 23s https://www.youtube.com/watch?v=3Mgi17T-O-c
Digitizing tools Mariëlle Geers-Plasmans (Geojuffie): “G04 Geavanceerd digitaliseren” Language(s): Dutch Time: 19min 7s https://www.youtube.com/watch?v=iBeeVV3LifI
Digitize and store points, lines and polygons including their style Hans van der Kwast: “Digitizing vectors in a GeoPackage in QGIS” Language(s): English Time: 19min 36s Chapters: introduction (start-0:12), creating a GeoPackage (0:12-1:30), adding points (1:30-2:28), editing points (2:28-4:33), editing lines (4:33-10:10), digitizing polygons (10:10-13:00), editing the attribute table (13:00-end) https://www.youtube.com/watch?v=H0Vy2NJl0O8
Digitize points and add attributes Hans van der Kwast: “Digitize Point Vector Layers in QGIS” Language(s): English Time: 4min 3s https://www.youtube.com/watch?v=zPv-TIsqUqI
Digitize line vector layers, work with the snapping toolbar and dissolve features with the same attribute Hans van der Kwast: “Digitize Line Vector Layers in QGIS” Language(s): English Time: 5min 22s Chapters: intro (start-0:15), create a new layer (0:15-4:00), dissolve a layer (4:00-end) https://www.youtube.com/watch?v=LYRk0eQGS54
Digitize polygons Hans van der Kwast: “Digitize Polygon Vector Layers in QGIS” Language(s): English Time: 3min 9s Chapters: intro (start-0:10), create a new layer (0:10-0:50), start digitizing (0:50-1:40), close the polygon (1:40-2:15), add a ring (2:15-end) https://www.youtube.com/watch?v=QKQOKw2qzIY
Digitizing points to the exact coordinates Erik Meerburg (Geogoeroe): “Punten digitaliseren op exacte coördinaten” Language(s): Dutch Time: 3min 42s https://www.youtube.com/watch?v=VV71KjvlTWQ
Create, edit and remove geometries Geographical data can be created by using geometries.
Draw scaled circles Stefan van der Spek: “MScU QGIS Q1 Making Circles” Language(s): English Time: 3min 24s https://www.youtube.com/watch?v=_w4_-dp-VIk
Using Scratch layers to draw points, lines and polygons Stefan van der Spek: “MScU GIS Q1 Sketching and Drawing” Language(s): English Time: 18min 50s Chapters: Introduction (start-1:20), finding the area (1:20-2:38), scratch layer (2:38-6:54), lines layer (6:54-11:46), areas layer (11:46-16:28), improvements (16:28-17:56), summary (17:56-end) https://www.youtube.com/watch?v=5DmWgiltHWc
Add and delete geometry Mariëlle Geers-Plasmans (Geojuffie): “G01 geometrie toevoegen en verwijderen” Language(s): Dutch Time: 4min 44s https://www.youtube.com/watch?v=WATnJt-iaso
Edit geometries Mariëlle Geers-Plasmans (Geojuffie): “G02 geometrie editen” Language(s): Dutch Time: 4min 50s https://www.youtube.com/watch?v=DM0Csd8bhNo
Snapping
Snapping can be used to match two polygons in case they do not.
Snapping Mariëlle Geers-Plasmans (Geojuffie): “G03 Snappen” Language(s): Dutch Time: 9min 44s https://www.youtube.com/watch?v=BuH5keMuqGc
Topology editing QGIS Training manual: “5.2. Feature Topology” Language(s): English Chapters: follow along: snapping, follow along: correct topological features, follow along: simplify feature, try yourself tool: add ring, try yourself tool: add part, follow along: reshape features, try yourself tool: split features, try yourself tool: merge features, in conclusion, what’s next https://docs.qgis.org/3.10/en/docs/training_manual/create_vector_data/topo_editing.html
Snap pour points and delineate iteratively the catchments of those points Hans van der Kwast: “Snap pour points and delineate multiple catchments in QGIS” Language(s): English Time: 5min 33s https://www.youtube.com/watch?v=Hqc_1CMadhA
Vector overlay tools
These tools are useful when multiple vector layer need to be combined. Users can clip, intersect or unify these layers for example.
Clip, intersection, union and symmetrical difference Hans van der Kwast: “GIS vector overlay tools: clip, intersection, union, (symmetrical) difference” Language(s): English Time: 5min 2s Chapters: introduction (start-0:35), clip tool (0:35-1:14), difference tool (1:14-2:03), union tool (3:04-4:01), symmetrical difference (4:01-end) https://www.youtube.com/watch?v=QBVv7h2Jhvo
Other tools and methods related to geometry
Add dotted lines when two surfaces overlap Mariëlle Geers-Plasmans (Geojuffie): “Overlappende vlakken” Language(s): Dutch Time: 2min 27s https://www.youtube.com/watch?v=EL4RrSXtNGA
Fix a geometry error for a state polygon of an admin boundary layer for India Ujaval Gandhi: “Handling Invalid Geometries (QGIS3)”/”Ongeldige geometrieën afhandelen (QGIS3)” Language(s): English, Dutch Chapters: overview of the task, get the data, procedure EN: https://www.qgistutorials.com/en/docs/3/handling_invalid_geometries.html NL: https://www.qgistutorials.com/nl/docs/3/handling_invalid_geometries.html
Create valid geometries Erik Meerburg (Geogoeroe): “Rudifun: valide geometrie maken” Language(s): Dutch Time: 7min 50s https://www.youtube.com/watch?v=LSXixj94uUk
Actions
An action is something that happens when a feature is clicked. This could be a webpage that opens or a Python that starts to run for example.
How to add custom actions QGIS training manual: “5.4. Actions” Language(s): English Chapters: follow along: add a field for images, follow along: creating an action, follow along: searching the internet, follow along: open a webpage directly in QGIS, in conclusion, what’s next https://docs.qgis.org/3.10/en/docs/training_manual/create_vector_data/actions.html
> QGIS Installation
Do you still need to install QGIS? The QGIS installation and update section explains how to install QGIS on Windows and macOS.
Useful Links
Ujaval Gandhi (QGIS Tutorials and Tips website)
Stefan van der Spek YouTube channel
Mariëlle Geers-Plasmans (Geojuffie) YouTube channel
Hans van der Kwast YouTube channel
Erik Meerburg (Geogoeroe) YouTube channel
#QGIS, #Geometries, #Digitizing, #Vector data, #Raster data, #Snap, #Clip, #Intersection, #Union, #Actions
Stefan van der Spek (2022, August 24). MScU QGIS Q1 Advanced Digitizing [Video]. YouTube.