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How to use Terrain Following to your advantage on Discovery 2

Brief explanation how what terrain following does and doesn't do on Discovery 2

Intro

Terrain following is an excellent and helpful feature we leverage on our Discovery 2 platform. This allows us to fly in challenging terrain, avoiding the tops of hills and maintaining range to the ground in the valleys.

 

Note: Terrain following is not currently utilized when flying to or returning from the mission. If you would like to learn more about how to plan with this in mind, please go to the bottom of this guide for the instructions

How to enable Terrain Following

  1. Make sure your Herelink controller or laptop is connected to the internet
  2. Plan your mission, as usual, using this guide: Planning your flights in QGroundControl
  3. Once you are happy with the area you are covering, check the "Vehicle follows terrain" box
  4. This will enable the terrain following. The settings can be left at their default.
  5. Save your flight. This will keep the altitudes assigned to the waypoints and be ready to use in the field.

How Does Terrain Following work?

Our terrain following pulls from an online database of ground altitudes. When making your missions, it downloads this data and uses it to assign altitudes to the waypoints on the flight. With extreme terrain change, it will add intermediate waypoints with altitudes for the drone to be at upon crossing.

 

How to use Terrain Following Properly

Terrain following is not a replacement for maintaining line of sight. The diligence in planning the launch locations and areas of flight is still critical. 

 

There is no terrain following on the leg to the flight area and on the returning leg. On the first leg, it will climb to the initial waypoint altitude as it flies. On the return leg, it will stay at the final waypoint's altitude and fly directly back home. Because of this, we recommend launching from the highest point of the site. This will accomplish two things:

  1. You are more likely to maintain radio communication
  2. You are more likely to maintain line of sight

This drawing shows the Yellow leg to the mission (not terrain following), the Green flight path of the mission(terrain following), and the Red return leg (not terrain following).

In this example, you can see that the drone has flown into the side of the hill. The good news is that we can prevent this with a straightforward step.

To prevent this from happening:

  1. Click the "B" button on the controller when the drone has finished the flight. This puts the drone in loiter mode, which is a GPS hold. 
  2. Move the left stick up to gain altitude. If the drone goes into a battery failsafe while in loiter mode, it will take control back. Click the "B" button again, and you will regain control
  3. The controller will display your altitude relative to takeoff. I recommend raising the drone's altitude until the displayed altitude reaches your desired height over your takeoff location.
    1. Ex: if I had programmed the mission to maintain 50 meters above the ground, I would raise the drone's altitude until it reads "50 meters relative to takeoff". 
    2. Because I launched from the highest point on sight, I know I will clear any trees on the site.
  4. Lastly, click the Return to Home button (it looks like a house). This will bring the drone back at a constant altitude 

 

This diagram shows what it looks like if you raise altitude and initiate the return to launch button.