Follow Terrain Beta - What Sensor Calculates Altitude?

I’m wanting to test the new follow terrain beta feature, at very low altitude ~15 feet AGL.

**Question:**I’m curious at low altitude, what sensor is used to determine height AGL? Does it use GPS or Object Avoidance Sensors (e.g. the underside ultrasonic range meter) to determine the height above ground level.

I’ve had issues with using GS Pro to fly low altitude missions (16.4 ft) and over time the drone ends up to be closer to 5 feet due to GPS errors. So it would be preferred if it uses relative sensors like ultrasonic range instead.


Terrain following in drone deploy? What are you flying?

I’m flying both Phantom 4 Pro V1 and V2.

I’m wanting to test the terrain following in drone deploy at 16 feet. However to ensure I get the image overlap I want, the drone must keep an accurate and consistent altitude of 16 feet AGL over variable elevation terrain.

It seems that accuracy would only be achievable with relative sensors.

There was a beta, but as far as I know it expired. @Jamespipe @Yusuf, Is it back?