Obtaining elevation data for points using QGIS

Question

I am new to QGIS.

I have points uploaded to QGIS that were collected from a GPS, and I need to get elevations for each point (I don't trust the elevation estimations of my GPS).

What is the best way to do this?

Additionally, I realize I'll likely need an elevation raster, and I'm wondering if the Google terrain hybrid or Google satellite hybrid will work or if there's a better option?

Answer 1

Basic steps to get elevation data in GPS points:

1. Obtain an elevation raster for your area of interest. You'll need a DEM (Digital Elevation Model) raster, which is a raster of pure elevation data without any labels or additional features. (Google terrain is not an elevation raster, it's a combination of a "hillshade" or "shaded relief" raster with additional map features like roads, towns, labels, etc.)

   • You can download a DEM from various sources. In the US you can get one from the National Map Viewer. For Europe (and possibly other parts of the world) try opendem.info.

   • Or you can try to connect to a DEM through a web service, which will save you from having to download and store the data locally. Connecting to a web service in QGIS can be rather tricky, because sometimes the connection just fails and the error message doesn't really explain how to fix it. Here are a few sources where you may be able to connect to an online DEM:

     • https://www.sciencebase.gov/catalog/item/543e6b86e4b0fd76af69cf4c
     • https://openmaptiles.com/dem/
     • https://www.usgs.gov/news/new-elevation-map-service-available-usgs-3d-elevation-program
   • If you search around on this stackexchange and also on Open Data stackexchange, you'll find other resources where you can obtain downloadable and online DEM's.

2. Add the elevation values to your point layer. You can use the Sample Raster Values processing algorithm (shown below) or the Point Sampling Tool plugin.

   

Answer 2

• You'll need to search for a high resolution elevation raster for your area.
• Open it in QGIS along with your GPS points.
• Make a copy of your GPS points.
• Use the 'Drape' tool in the processing toolbox to add z values to the points using the elevation raster.

Google terrain/satellite is not going to work. You will have to source a high resolution elevation raster. If you're in the US, check out USGS 3dep for elevation rasters. You will need 1m resolution if you want improved accuracy over your GPS device (which are usually around 10m).