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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  


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.  


> 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


QGIS Training Manual

QGIS User Guide

GIS OpenCourseWare

Ujaval Gandhi (QGIS Tutorials and Tips website)

TOI-pedia

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. 

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