I see almost no need to follow the terrain uphill. Downhill, now that would be fantastic. Why is this not an option? Are the bottom sensors not capable? Is it a safety concern of some sort? Flying downhill chasing action is extremely difficult, but oh so cool. Downhill terrain follow would make this type of shot so much easier. I did hear somewhere that after you set the terrain follow height, if you then fly over downhill terrain while pushing the left stick all the way down it will never go lower than than the height you set. Is this true? If so, I could probably make that work, but I am currently in flat Florida and cannot test this theory. Anyone know?

The Mavic user manual (v1.8) seems to be very particular about stating that downhill Terrain Follow Mode will not work, which is a shame, as you say.  Quite why, I do not know, but some of the experienced Mavic/DJI operators here may have the answer.

"Terrain Follow Mode
The Downward Vision System is utilized in Terrain Follow Mode to maintain a height above ground between 1 and 13 meters. This mode is designed for use on grassland sloped at no more than 20 degrees.
Enable the Terrain Follow Mode by tapping the Intelligent Flight Mode icon in the DJI GO 4 app. When this mode is enabled, the aircraft’s current height will be recorded. The aircraft will maintain the recorded height during flight and ascend when the slope rises. However, the aircraft will not descend in downward slopes.

• It is important that you only fly in conditions where the Vision Position System can function correctly; otherwise the Terrain Follow Mode will not work."
  

My Mavic will fly downhill following the terrain, as long as you pull the pitch stick back, it should not fly lower than the set height.

willcub Posted at 2017-11-5 11:25
My Mavic will fly downhill following the terrain, as long as you pull the pitch stick back, it should not fly lower than the set height.

Sweet. Glad to hear that’s true.

The aircraft will not descend in downward slopes in the concern of flight safety. And like 3# mentioned, the user can pull down the throttle stick and push the pitch or roll stick to fly the aircraft.

DJI Thor Posted at 2017-11-6 01:03
The aircraft will not descend in downward slopes in the concern of flight safety. And like 3# mentioned, the user can pull down the throttle stick and push the pitch or roll stick to fly the aircraft.

I fly where there are no people or structures. What is unsafe about this? Dji needs to stop catering to the safety of beginner flyers. There are situations where autonomous downhill flight is perfectly safe even if things go wrong.

Use Active Track Profile mode for downhill action shot