3. Download DEM

For the Rur study area, we will download the tiles from the SRTM 1 Arc-Second global data set. Since the end of 2014 a 1-arc second global digital elevation model (approximately 30 meters at the equator) has been released as open data. Most parts of the world have been covered by this dataset ranging from 54 degrees south to 60 degrees north latitude. A description of the SRTM data products can be found here.

The following steps explain how to download the SRTM DEM tiles for the study area using the OpenTopography DEM Downloader plugin. With the plugin you can download DEMs from OpenTopography.org for a user-selected extent.

1. Start QGIS Desktop. We’ll start with a new project. In the Browser panel, add the folder with the data for this lesson to the Favorites as you learned in the previous lesson.

2. Drag the boundingbox.shp layer from the Browser panel to the map canvas.

This polygon defines the boundary of our initial analysis. Normally you have to create such a polygon yourself or use the map canvas coordinates. We need this to clip the DEM to the study area. Note that the projection of the project (on-the-fly reprojection) is now set to the projection of the boundingbox layer. You can check it in the lower right corner of the screen.


We will work in this projection during this exercise.

3. Install the OpenTopography DEM Downloader plugin from the Plugins Manager. Go to the main menu and choose Plugins | Manage and Install Plugins....


4. In the Plugins Manager search for OpenTopography and install the plugin.


5. Click the OpenTopography DEM Downloader  button in the toolbar.

6. In the OpenTopography DEM Downloader dialog, choose SRTM 30m from the drop-down menu under Select DEM to download.

Note that you can choose 12 different global DEM data products. The one that works best for your study area, depends on its size and landscape. For larger areas you might want to choose a coarser spatial resolution.

7. At Define extent to download, click the little arrow and choose Calculate from Layer | boundingbox. It will fill in the coordinates of the extent of the boundingbox layer.



Now you need to Enter your API key.

8. Go to your web browser and navigate to https://opentopography.org/.


9. There click on MyOpenTopo.

10. Click Create new account and fill in the form to register. Check your e-mail (also spam folder) for the activation steps.

11. Login to MyOpenTopo and click on Get an API Key.

12. Next, click on the button, Request API key and you will be assigned an API key. Click  to copy the API key.

13. Go back to QGIS and past the API key in the OpenTopography DEM Downloader dialog.

14. Click  to browse to a folder where you want to store the data for this project. Remember to stick to the good practice instructions for file and folder names (no spaces, accents, -, etc.). Always use the  button in QGIS dialogs to choose the output location! Name the file SRTM.tif. 

The dialog should now look like this:




15. Click the Run button.

16. After completion, click Close to close the OpenTopography DEM Downloader dialog.

17. Right-click on the SRTM.tif layer and choose Properties to review the metadata under the Information tab.



  • What is the projection?
  • What are the map units?

Watch this video to check the steps: