Overview of using DEMs
In recent years, terrain follow missions using commercial drones to acquire high quality data has become commonplace. Drones equipped with the correct sensors and following an accurate flight path have made this possible. However, one challenge in conducting terrain follow flights, is to acquire an accurate Digital Elevation Model of the target area. The DEM can be used to better understand the area's terrain and create a terrain-following flight path for the drone.
Whilst high-resolution DEMs are generally available from local mapping agencies such as EASA, Ordnance survey, etc, one good place to start is to use NASA's global SRTM data which is accurate to 30m.
What's the best way to download and use NASA SRTM data? We'll break it down in the post below.
Steps
Here's a list of steps you can follow to download and use NASA SRTM data for free. If you prefer watching a video instead, here's one below:
Step 1. Create an account with USGS Earth Explorer
The USGS Earth Explorer is a web tool that allows you to find and download NASA SRTM datasets for your target area. Before you can use this tool, you will have to create an account with USGS Earth Explorer if you wish to download and use the data.
Step 2. Set your area of interest in the “Search Criteria” tab
Once you have created an account with USGS Earth Explore, you can now search for your target area in the search criteria tab. You can do this by marking the coordinates of your target area on the map.
Step 3. Select your data to download in the “Data Sets” tab
You can now use the datasets tab to download the DEM data. The USGS Earth Explorer offers a number of different datasets - aerial imagery, AVHRR, commercial imagery, digital elevation models, Landsat, LiDAR, MODIS, Radar and more. Obviously, in our case, we would select the digital elevation models and continue.
Step 4. Filter your data in the “Additional Criteria” tab
You can then filter your search criteria to really narrow down to the data you need. You should be able to display the data as tiles on the map as shown below.
Step 5. Download free Landsat imagery in the “Results” tab
Once you're happy with the dataset you can then view it on the map and hit download to start the download process.
Step 6: Plan a Drone Mission in Hammer Missions
Once you've got the data downloaded on your computer, you can then split it into smaller chunks using GIS tools like QGIS or ArcGIS. You can then transfer this data to your iPad and start planning your drone mission!
To learn more about using terrain follow and digital elevation models in Hammer, please visit our guide on Terrain Follow Missions.
Conclusion
We hope this guide helped you search and download the appropriate DEM data from the NASA SRTM dataset. If you have any questions on terrain following for drone missions or using DEM data, please feel free to get in touch with us at team@hammermissions.com.
If you are planning to fly terrain follow drone missions in the upcoming year, feel free to get started with Hammer with our 14-Day Free Trial.
We wish you the very best for your upcoming missions!
- The Hammer Team