DJI Mavic, Air and Mini Drones
Friendly, Helpful & Knowledgeable Community
Join Us Now

Why can't the Mavic follow in the Z axis (Active Track)

gow7

Well-Known Member
Joined
Apr 23, 2017
Messages
50
Reactions
23
I'm curious, if it is capable of following both in X and Y axis why can't in the Z? What's the limitation?
It could do a mix of a threshold between the camera looking up and the drone gaining some vertical distance. Does the Mavic Pro 2 overcome this limitation (it has upward sensors, it should help)?

I ask because I'm a climber ?
Thanks.
 
I'm curious, if it is capable of following both in X and Y axis why can't in the Z? What's the limitation?
It could do a mix of a threshold between the camera looking up and the drone gaining some vertical distance. Does the Mavic Pro 2 overcome this limitation (it has upward sensors, it should help)?

I ask because I'm a climber ?
Thanks.

Something about it will if you have a device with a GPS or barometer in it. Don’t remember all the details but hopefully someone will.
 
The "problem":

While it’s been awhile since I’ve used active track like that I believe it should go out and at least use the gimbal to look up.

Try enabling +30 degree gimbal extension so it is able to look up. Also try playing with the different active track modes. I know there’s a minimum distance from an object to track it so make Shute you aren’t too close.
 
it's already enabled but it has a limit. The Mavic could understand that and move up vertically
 
The Mavic won't "follow" up and down but it _will_ maintain it's altitude above ground as long as it is within the downward sensor ranges.

Reason why it won't do otherwise... GPS altitude is not accurate.
 
as long as it is within the downward sensor ranges.

What happens if it is not? And if I disable the sensors?
I believe they only aid the smoothness and avoid collisions.

Reason why it won't do otherwise... GPS altitude is not accurate.

But why does it need the GPS to follow a "shape"? In the case of Mavic Pro 2 that has "360 sensors" shouldn't this be enough to avoid collisions and continue to follow a "shape" safely? ?

If we use the Active Track but in the Profile or Trace mode I don't believe the GPS is making any difference either, sensors may be helping the video stabilization and with the collisions, and Active Track can be used inside a garage without GPS or am I wrong?

Thanks :)
 
Last edited:
All of these sensors
- Only work at close range, and limited speed
- Are to be considered "helpers", they don't always work reliably so you can't rely on them to navigate. They likely consider they'd get too many crashes and complaints if they enabled such following.
 
What happens if it is not? And if I disable the sensors?
I believe they only aid the smoothness and avoid collisions.
It uses the sensor to change altitude. So if they are disabled, it won't adjust to the terrain.



But why does it need the GPS to follow a "shape"? In the case of Mavic Pro 2 that has "360 sensors" shouldn't this be enough to avoid collisions and continue to follow a "shape" safely?
I would guess that perhaps it is possible to use the _camera_ and software to determine if the object is going up or down but I suspect 1) this is very difficult and 2) would require even more processing power. Think about the software involved. How would it tell that the object is changing in altitude? Larger and smaller? This would happen the closer nd further it got as well. We know that the camera can move up and down and perhaps the Mavic could be programmed to sense this as altitude change but I suspect this is very difficult to do and then we might hit problem #2.

If we use the Active Track but in the Profile or Trace mode I don't believe the GPS is making any difference either, sensors may be helping the video stabilization and with the collisions, and Active Track can be used inside a garage without GPS or am I wrong?
Correct, GPS is not being used to track. What I was saying is that the Mavic does not use GPS to adjust altitude, it used the downward sensors only.
 
I would guess that perhaps it is possible to use the _camera_ and software to determine if the object is going up or down but I suspect 1) this is very difficult and 2) would require even more processing power. Think about the software involved. How would it tell that the object is changing in altitude? Larger and smaller? This would happen the closer nd further it got as well. We know that the camera can move up and down and perhaps the Mavic could be programmed to sense this as altitude change but I suspect this is very difficult to do and then we might hit problem #2.

Interesting thoughts. I agree with you.

And if we think about the Active Track (Trace) only in terms of X and Y, I guess the drone "knows" that it has to follow forward because the image is getting smaller. But it can get smaller in the top of the screen, so the drone could think "should I follow forward or up? or both?". Definitely not an easy algorithm.

I think it could start by following up if the size of the "shape" didn't change must (%), while the "shape" moved up to the top margins, and also the fact that the camera can go up and down as you've mentioned. But yeah, diagonals would be very hard to distinguish between "following forward" and "following up".

It would be cool if some official explanation would be given, maybe @msinger could help ^^
 
Last edited:
Oops did not see previous reply. [emoji33]

We know fc has concept of proximity to target given the behavior in Active Track. This is like based on size of Target as camera sees it. Modifying active track to consider upper and lower gimval limits as triggers to increase or decrease altitude dependant upon proximity to target change over time.

If subject proximity delta rate is LOW and gimbal limit reached, translate accordingly in Z plane.

Conversely if rate of proximity change is HIGH (subject rapidly approaching or moving away) proceed as usual and translate accordingly in the X and Y planes.

Seems simple once interaction between behaviors is tested and corrected for.
 
Last edited:
  • Like
Reactions: gow7