QGIS | Digital Elevation Model (DEM)
> Objective
The students will learn more about digital elevation models (DEM)
This section shows how to create digital elevation models (DEM)
This section shows how to create hypsometric curves
The students will learn how to compute the volume under a certain location
The students will learn how to add hillshades to digital elevation models (DEM)
This section covers how to clip digital elevation models (DEM) by polygon
The section contains information on how to load and prepare DEM data from Shuttle Radar Topography Mission (SRTM) and OpenTopography
> Index / Table of Contents
Introduction
Tutorial(s)
Theory
Create Digital Elevation Models (DEM)
Create hypsometric curves
Volume computation
Add hillshades
Clip DEM by polygon
Load and prepare DEM data
QGIS installation
> Summary and Highlights
Introduction
Digital elevation models (DEM) are 3D models representing the elevation of a terrain and the objects placed on it. DEM can be modelled and visualised in QGIS. The first part of this section explains what a DEM is. The second one shows how to create a DEM. Then, tutorials are listed demonstrating different tools and operations that are related to DEM.
Tutorial(s)
Theory
Introduction to Digital Elevation Models (DEM) Hans van der Kwast: “Digital Elevation Models in GIS (theory) - updated” Language(s): English Time: 11min 56s Chapters: introduction (start-1:37), DEM acquisition (1:37-4:28), use of DEMs (4:28-6:01), example of French Alpes (6:01-7:27), hillshade (7:27-8:09), contour lines (8:09-8:52), 2.5D/3D (8:52-9:15), drape orthophoto over DEM (9:15-9:34), slope (9:34-9:56), aspect (9:56-10:34), viewshed (10:34-10:46), topographic wetness index (10:46-11:08), transects (profile tool) (11:08-end) https://www.youtube.com/watch?v=pnAdasqHxGk
Create Digital Elevation Models (DEM)
Create a DEM visualisation using vector lines Hans van der Kwast: “Visualisation of DEM as vector lines using QGIS” Language(s): English Time: 4min 55s Chapters: intro (start-0:15), creating the grid (0:15-1:47), translating the grid (1:47-3:19), visualisation (3:19-end) https://www.youtube.com/watch?v=uxMBdI3JEak
Create hypsometric curves
Hypsometric curves show the proportions of land area at different elevations.
Create a hypsometric curve (histogram or cumulative distribution functions of elevations) Hans van der Kwast: “Create Hypsometric Curve from a DEM using QGIS” Language(s): English Time: 9min 12s Chapters: introduction (start-0:37), calculate catchment area (0:37-1:10), divide model into classes (1:10-1:53), reclassification by table (1:53-2:55), polygon eyes (2:55-3:51), dissolve (3:51-4:32), area (4:32-5:54), export (5:54-6:20), edit in LibreOffice (6:20-7:15), save the file (7:15-7:33), open the table (7:33-7:55), create the plot (7:55-end) https://www.youtube.com/watch?v=RybzfbtqdLs
Quickly create a hypsometric curve (histogram or cumulative distribution functions of elevations) in a fast way Hans van der Kwast: “Create a Hypsometric Curve in QGIS, the fast way” Language(s): English Time: 3min 36s Chapters: introduction (start-0:20), create a hypsometric curve (0:20-1:06), results (1:06-1:55), plotting (1:55-end) https://www.youtube.com/watch?v=NKpfxdzoVcM
Volume computation
Determine the volume below a given elevation Hans van der Kwast: “Calculate volumes from a DEM in QGIS” Language(s): English Time: 8min 28s https://www.youtube.com/watch?v=sOj_IT8A4Bw
Add hillshades
Hillshades helps to visualise the relief of the terrain by using light and shadows.
Style DEM as a color hillshade Hans van der Kwast: “Style DEMs with Color Hillshade in QGIS” Language(s): English Time: 1min 57s https://www.youtube.com/watch?v=Y-M9y9eL0uM
Create contours and hillshades Ujaval Gandhi: “Working with Terrain Data (QGIS3)”/”Werken met gegevens over het terrein (QGIS3)” Language(s): English, Dutch Chapters: overview of the task, get the data, procedure EN: https://www.qgistutorials.com/en/docs/3/working_with_terrain.html NL: https://www.qgistutorials.com/nl/docs/3/working_with_terrain.html
Clip DEM by polygon
Clip the channels line vector and DEM to the catchment boundary polygon Hans van der Kwast: “Clip Channels and DEM to Catchment Boundary Polygon in QGIS” Language(s): English Time: 2min 41s Chapters: intro (start-0:15), channels (0:15-0:35), result (0:35-1:00), clip DEM (1:00-1:10), ruler catchment (1:10-1:20), rectangular raster (1:20-1:40), duotif (1:40-2:00), hillshade (2:00-end) https://www.youtube.com/watch?v=jVW-9FL55_Y
Clip a large DEM with a bounding box polygon Hans van der Kwast: “Clip Raster by Mask Layer in QGIS” Language(s): English Time: 1min 22s https://www.youtube.com/watch?v=M1PMzGYwAnQ
Load and prepare DEM data
Mosaic DEM tiles from Shuttle Radar Topography Mission (SRTM) Hans van der Kwast: “Mosaic DEM Tiles in QGIS by Creating a Virtual Raster” Language(s): English Time: 1min 55s https://www.youtube.com/watch?v=RSH_rAJXqa8
Mosaic a raster with the elevation values of Sri Lanka Ujaval Gandhi: “Raster Mosaicing and Clipping (QGIS3)”/”Mozaïeken en clippen (QGIS3)” Language(s): English, Dutch Chapters: overview of the task, get the data, procedure EN: https://www.qgistutorials.com/en/docs/3/raster_mosaicing_and_clipping.html NL: https://www.qgistutorials.com/nl/docs/3/raster_mosaicing_and_clipping.html
Add a DEM to a project using the OpenTopography DEM Downloader, which enables users to download topography data from OpenTopography.org. Hans van der Kwast: “Download DEMs in QGIS for a Specified Extent with the OpenTopography DEM Downloader” Language(s): English Time: 3min 59s https://www.youtube.com/watch?v=EMwPT7tABCg
> 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
Hans van der Kwast (YouTube channel)
Ujaval Gandhi (QGIS Tutorials and Tips website)
Hans van der Kwast. (2019, August 19). Visualisation of DEM as vector lines using QGIS [Video]. YouTube.