Altitude for RTH if I set a new Home Point during flight

[Meta4]

Ok after thinking about it im either learning something today or everyone is lol. I didnt know the recorded RTH position took in consideration of ground level. I mean I know it has to know the the ground level in order to climb to the height you have it set at but I guess I assumed that was 2 seperate things. I assumed that GPS locations was just longitude and and latitude. Ive never heard of GPS being a 3 position thing. I thought it just added in your start off ground level to the GPS coordinates. Because if that were the case that its a 3 part coordinate then why wouldn't it tell you the 3rd part of ground level when you use "find my drone" it only gives you lat and long. I had my drone stuck in a tree once and it doesnt say whether its on the ground or 50 ft in the air off from home point. Because that would come in handy if find my drone did do that. You'd know if you should be looking on the ground or up in a tree and I feel if GPS had that ability it should certainly let you utilize wouldnt you think? Why would purposesly leave that out of the equation. I just assumed it used the the ground level at first to rise to the altitude you set it at then changed over to GPS location to get it above HP and then just started to decend until the sensors picked up ground level no matter how far it was or close it was. That would also explain why it doesnt take into consideration of height when determining if you're far enough from HP to activate RTH. What is it 30 meters away from home point correct? If it took in consideration of your ground point height then If you were 31 meters up youre technically more than 30 meters away from HP. Im thinking it only knows ground point to go to preset altitude for RTH only using how far the it has calculated your upward rise from zero when you started the flight. Which would also explain why you can reset HP at anytime during your flight and it doesn't need to calculate ground level. When you reset HP during flight you arent giving it a height just long and lat. You move the image 2d not 3d. Am I right here or have I had to much to drink tonight lol

Boy .. that's a complicated question
It made my head hurt.
I'll try to simplify the answer.
1. GPS is a three dimensional thing
2. DJI drones use GPS for horizontal position (2D) and use the barometric sensor in the IMU for height.
3. The recorded home point has no height, it's just lat & long coordinates.
4. Find my drone is a blunt instrument of only limited value.
If you investigate the actual flight data for a drone lost in a tree, you get the GPS location and the height data

And in case it helps understand ..
The zero height is separate from the home point.
The zero height is established on powering up while the home point isn't recorded until later when the drone gets good GPS location data.

 

[FlyBackOU812]

Boy .. that's a complicated question
It made my head hurt.
I'll try to simplify the answer.
1. GPS is a three dimensional thing
2. DJI drones use GPS for horizontal position (2D) and use the barometric sensor in the IMU for height.
3. The recorded home point has no height, it's just lat & long coordinates.
4. Find my drone is a blunt instrument of only limited value.
If you investigate the actual flight data for a drone lost in a tree, you get the GPS location and the height data

And in case it helps understand ..
The zero height is separate from the home point.
The zero height is established on powering up while the home point isn't recorded until later when the drone gets good GPS location data.

Everything you said about RTH being only 2d and doesn't consider height is exactly what I thought and said whether I was clear enough on how I said it lol. What I didnt know was that normal GPS was 3d and thats why I didnt believe RTH recorded it that it used some other way when it calculates your height which again I was right about if you are correct which I believe you sound like you know what you're talking about about. At least it sounds that way lol. Now as far as the other part of with find my drone coordinates is where im a little unsure of but will most definitely have another look into it cuz ive used it many times and ive never seen anything that that tells you its height. Only Lat long but im not saying you're wrong just that I've never seen it and ive studied it pretty closely. But im about to look into that right now cuz tgat would have helped me a a couple times and I cant see me missing something like that so I hope you're correct and im wrong. Id rather be wrong and know that it has it if I ever need it again than be right and not have it. You can bet ill be back to report on that ?

 

[DanMan32]

Everything you said about RTH being only 2d and doesn't consider height is exactly what I thought and said whether I was clear enough on how I said it lol. What I didnt know was that normal GPS was 3d and thats why I didnt believe RTH recorded it that it used some other way when it calculates your height which again I was right about if you are correct which I believe you sound like you know what you're talking about about. At least it sounds that way lol. Now as far as the other part of with find my drone coordinates is where im a little unsure of but will most definitely have another look into it cuz ive used it many times and ive never seen anything that that tells you its height. Only Lat long but im not saying you're wrong just that I've never seen it and ive studied it pretty closely. But im about to look into that right now cuz tgat would have helped me a a couple times and I cant see me missing something like that so I hope you're correct and im wrong. Id rather be wrong and know that it has it if I ever need it again than be right and not have it. You can bet ill be back to report on that [emoji1787]

I read half through this and got dizzy.

Altitude by GPS is NOT used AT All for flight control. Really GPS altitude can't be used since GPS altitude is AMSL, not AGL. Unless it's in VPS range there's no way for the AC to know how high the ground is. No matter if barometer or GPS is used (it's barometer), it has to be relative to takeoff since that's all it knows. If it used GPS, it would take current AMSL and subtract takeoff AMSL.

You can overall exceed 500m up a mountain, but you'd have to land at higher altitudes to reset the altimeter to zero. That of course would also reset your HP, though you can set it back to RC location if your you have GPS on your mobile or change HP from the map.

 

[Meta4]

Only Lat long but im not saying you're wrong just that I've never seen it and ive studied it pretty closely.

FMD doesn't give you any height reference or much else that could be useful except a lat/long location..
But I don't have any faith in FMD or use it at all because it can only show where the app last had contact with the drone.
And that's no use at all if the drone was still flying when it lost contact.

I use the actual recorded flight data to find lost drones.
The data is what gives the height, not FMD.

 

[FlyBackOU812]

I read half through this and got dizzy.

Altitude by GPS is NOT used AT All for flight control. Really GPS altitude can't be used since GPS altitude is AMSL, not AGL. Unless it's in VPS range there's no way for the AC to know how high the ground is. No matter if barometer or GPS is used (it's barometer), it has to be relative to takeoff since that's all it knows. If it used GPS, it would take current AMSL and subtract takeoff AMSL.

You can overall exceed 500m up a mountain, but you'd have to land at higher altitudes to reset the altimeter to zero. That of course would also reset your HP, though you can set it back to RC location if your you have GPS on your mobile or change HP from the map.

I read half through this and got dizzy.

Altitude by GPS is NOT used AT All for flight control. Really GPS altitude can't be used since GPS altitude is AMSL, not AGL. Unless it's in VPS range there's no way for the AC to know how high the ground is. No matter if barometer or GPS is used (it's barometer), it has to be relative to takeoff since that's all it knows. If it used GPS, it would take current AMSL and subtract takeoff AMSL.

You can overall exceed 500m up a mountain, but you'd have to land at higher altitudes to reset the altimeter to zero. That of course would also reset your HP, though you can set it back to RC location if your you have GPS on your mobile or change HP from the map.

Talk about getting dizzy reading mine? Atleast I'm speaking English lol. Not everyone, no, most don't know what all those abbreviations mean. Maybe if you live and breath daily in the drone communities and thats all you do but most of us don't. Sounds cool and like you're smart and all but most could care less how smart we sound, just that we know what we're talking about when giving advice and it seems you do but what good does knowing everything if normal people don't know how to translate. Just a thought

 

[John235]

Ok after thinking about it im either learning something today or everyone is lol. I didnt know the recorded RTH position took in consideration of ground level. I mean I know it has to know the the ground level in order to climb to the height you have it set at but I guess I assumed that was 2 seperate things. I assumed that GPS locations was just longitude and and latitude. Ive never heard of GPS being a 3 position thing. I thought it just added in your start off ground level to the GPS coordinates. Because if that were the case that its a 3 part coordinate then why wouldn't it tell you the 3rd part of ground level when you use "find my drone" it only gives you lat and long. I had my drone stuck in a tree once and it doesnt say whether its on the ground or 50 ft in the air off from home point. Because that would come in handy if find my drone did do that. You'd know if you should be looking on the ground or up in a tree and I feel if GPS had that ability it should certainly let you utilize wouldnt you think? Why would purposesly leave that out of the equation. I just assumed it used the the ground level at first to rise to the altitude you set it at then changed over to GPS location to get it above HP and then just started to decend until the sensors picked up ground level no matter how far it was or close it was. That would also explain why it doesnt take into consideration of height when determining if you're far enough from HP to activate RTH. What is it 30 meters away from home point correct? If it took in consideration of your ground point height then If you were 31 meters up youre technically more than 30 meters away from HP. Im thinking it only knows ground point to go to preset altitude for RTH only using how far the it has calculated your upward rise from zero when you started the flight. Which would also explain why you can reset HP at anytime during your flight and it doesn't need to calculate ground level. When you reset HP during flight you arent giving it a height just long and lat. You move the image 2d not 3d. Am I right here or have I had to much to drink tonight lol

I believe GPS positioning is indeed only two dimensional. The bird has no way of knowing altitude (asl), unless it would refer to a map, which I believe it does not. It finds "height" (agl) by comparing barometric pressure with take off location pressure, so that is an estimate value. Once at the home point in rth, I believe it uses visual sensors and sonar to sense the ground. Mine shows a display indicating distance to an obstacle (the ground).
Guys, am I correct?

 

[Zbip57]

I didn't know the recorded RTH position took in consideration of ground level.

The drone measures height via a barometric altimeter. Whatever the actual local barometric pressure reading is, at takeoff the drone registers and records that value as zero altitude. It then calculates its altitude in flight relative to that inital zero height based on how much the air pressure changes as the drone climbs or descends.

You can select and record a new Home Point while in flight but, as you've noted, the GPS location is only ever recorded in 2 dimensions, latitude & longitude. The drone's current height continues to be referenced back to the zero altitude recorded at its takeoff location.

I had my drone stuck in a tree once and it doesn't say whether its on the ground or 50 ft in the air off from home point. Because that would come in handy if find my drone did do that.

There is a clever, but not cheap, drone tracker called Marco Polo.
eurekaproducts.com/rc-model-tracking-and-recovery/

There are lots of Youtube videos showing how it works. Search for "Marco Pole drone tracker".

Hold the display screen positioned horizontally. The display then indicates a signal strength and points left or right in the direction to your downed drone. The signal strength increases as you home in to find the drone.

But the neat thing is that the tracker will also indicate up or down if you roll the display screen tilted on edge. Once you've tracked the drone to where you get 100% signal strength, when holding the tracker on its edge the arrow in the display will point up into the tree, or down into the hole.

Sadly the transceiver device that mounts on the drone weighs 12 grams, so that would put your Mini over the magic 250 gram limit.

 

[Zbip57]

I believe GPS positioning is indeed only two dimensional. The bird has no way of knowing altitude (asl), unless it would refer to a map, which I believe it does not.

There are aerial mapping apps that actually do this, i.e. refer to a map.

When planning the mapping flight route, to take multiple overlapping photos, you can set it to fly the entire plot in a flat plane at a single preset altitude, or you can set it to fly the plot in a terrain following height set to hold a predetermined height above ground.

The way it does this is the app uses something like Google Earth, which already knows the terrain height above sea level at each of the waypoints needed for the mapping flight. The app then automatically adjusts the drone's waypoint heights up/down to maintain the chosen height above ground along the way.

The drone itself still has no way of measuring its current height above ground at each point. It's still just measuring its own barometric altitude referenced to the spot it marked as zero upon takeoff. It's just responding to the wapoint instructions that were uploaded from the app.

 

[FlyBackOU812]

The drone measures height via a barometric altimeter. Whatever the actual local barometric pressure reading is, at takeoff the drone registers and records that value as zero altitude. It then calculates its altitude in flight relative to that inital zero height based on how much the air pressure changes as the drone climbs or descends.

You can select and record a new Home Point while in flight but, as you've noted, the GPS location is only ever recorded in 2 dimensions, latitude & longitude. The drone's current height continues to be referenced back to the zero altitude recorded at its takeoff location.



There is a clever, but not cheap, drone tracker called Marco Polo.
eurekaproducts.com/rc-model-tracking-and-recovery/

There are lots of Youtube videos showing how it works. Search for "Marco Pole drone tracker".

Hold the display screen positioned horizontally. The display then indicates a signal strength and points left or right in the direction to your downed drone. The signal strength increases as you home in to find the drone.

But the neat thing is that the tracker will also indicate up or down if you roll the display screen tilted on edge. Once you've tracked the drone to where you get 100% signal strength, when holding the tracker on its edge the arrow in the display will point up into the tree, or down into the hole.

Sadly the transceiver device that mounts on the drone weighs 12 grams, so that would put your Mini over the magic 250 gram limit.

Pretty sure I just seen a new RIF tracker that weighs little to nothing advertised somewhere here in the US but I was having conversation with someone and didn't get all the details but I was thinking it would be pretty nice to have for my Mini if it wasn't to much $ but I have a Mavic Pro also, I just dont fly it very often cuz

The drone measures height via a barometric altimeter. Whatever the actual local barometric pressure reading is, at takeoff the drone registers and records that value as zero altitude. It then calculates its altitude in flight relative to that inital zero height based on how much the air pressure changes as the drone climbs or descends.

You can select and record a new Home Point while in flight but, as you've noted, the GPS location is only ever recorded in 2 dimensions, latitude & longitude. The drone's current height continues to be referenced back to the zero altitude recorded at its takeoff location.



There is a clever, but not cheap, drone tracker called Marco Polo.
eurekaproducts.com/rc-model-tracking-and-recovery/

There are lots of Youtube videos showing how it works. Search for "Marco Pole drone tracker".

Hold the display screen positioned horizontally. The display then indicates a signal strength and points left or right in the direction to your downed drone. The signal strength increases as you home in to find the drone.

But the neat thing is that the tracker will also indicate up or down if you roll the display screen tilted on edge. Once you've tracked the drone to where you get 100% signal strength, when holding the tracker on its edge the arrow in the display will point up into the tree, or down into the hole.

Sadly the transceiver device that mounts on the drone weighs 12 grams, so that would put your Mini over the magic 250 gram limit.

I also have MP1. that was my first drone almost 5 years ago. Its been replaced twice since and doesn't have many flight hours on it cuz I'd rather put the miles and risk on the much cheaper mini not to mention people just dont seem to hassle me at all in public places like the beach which is where I live and fly most. I think when they see the mini its so small like a kids toy so maybe they don't think the camera is great and its just kid quality camera ?. Thats my best guess. But I seen a new RIF tracker advertised recently that I wanted to check out cuz it weighs little to nothing it seemed