Just got the Mini 3 a couole of weeks ago. Was going to shoot some waterfalls when i fly over the pool to get shots of the waterfall the drone starts decending. Takes a good bit of upward stick pressure to keep it from going in to the water. Is this normal?

No, it's not normal.
Post flight data and it might help explain what's causing the issue.

Go to http://www.phantomhelp.com/LogViewer/Upload/
It has instructions to find the .txt file from your phone or tablet which you can upload to that site
Upload it and it gives you a summary of the flight data.
Post a link to that summary.

Or just post the .txt file

Labroides Posted at 4-6 07:30
No, it's not normal.
Post flight data and it might help explain what's causing the issue.

Thanks. I dont use a phone or tablet. Use the RC controller. Can I access the logs using it?

It's normal with these drones

All DJI drones come equipped with VPS, a technology that maps the surface below to help position the drone. When flying over water, however, light reflecting off of the surface can cause issues with this technology. Because of this, it’s best to maintain a height of at least two meters above the water. If you have to fly below this height for a special shot, we recommend you turn off the VPS to avoid any unstable actions by the drone. Caution: When you disable the VPS of your aircraft and the distance between water surface and drone is smaller than 2 meters, you should fly the drone with a low speed in your FOV (field of view). Also, the height needs to be adjusted frequently since the aircraft could possibly drift downwards. Be aware that the minimum height has to be above 1 meter when flying over water.

https://store.dji.com/guides/how-to-fly-safely-over-water/

But you can still share your flight log it will always be interesting because there may be another problem. Labroides is the right man for this kind of analysis.

HOW TO: Copy TXT flight logs from DJI RC remote controller | DJI Mavic, Air & Mini Drone Community (mavicpilots.com)

Be wary when low over water and watch the drone's height carefully, preferrably eyes on the drone itself. Be ready to give it some throttle if you think it is descending, better to lose the shot than the drone..

robnor1 Posted at 4-6 08:57
Thanks. I dont use a phone or tablet. Use the RC controller. Can I access the logs using it?

Your RC controller is an Android tablet with joysticks.
Yes, you can access the data.
https://mavicpilots.com/threads/ ... -controller.127069/

LV_Forestry Posted at 4-6 10:02
It's normal with these drones

All DJI drones come equipped with VPS, a technology that maps the surface below to help position the drone. When flying over water, however, light reflecting off of the surface can cause issues with this technology. Because of this, it’s best to maintain a height of at least two meters above the water. If you have to fly below this height for a special shot, we recommend you turn off the VPS to avoid any unstable actions by the drone. Caution: When you disable the VPS of your aircraft and the distance between water surface and drone is smaller than 2 meters, you should fly the drone with a low speed in your FOV (field of view). Also, the height needs to be adjusted frequently since the aircraft could possibly drift downwards. Be aware that the minimum height has to be above 1 meter when flying over water.

It's normal with these drones

No ... it's not normal at all.
DJI's "guide" is quite misleading.
They make good drones but are very poor on documentation.

robnor1 Posted at 4-6 08:57
Thanks. I dont use a phone or tablet. Use the RC controller. Can I access the logs using it?

As well as the suggestions posted above you might like to have a look at post #7 in the thread
https://forum.dji.com/forum.php? ... p;page=1#pid3014166
If the link doesn't work the thread has the name "Can anyone help me retrieve my flight logs?" and is in the "DJI Mini 3 Pro" section

Hi, robnor1. Thank you for reaching out. It is not recommended to fly an aircraft within 10 meters above the water. The aircraft flies by visual positioning. Be careful to avoid areas with specular reflection such as water or snow. We recommend that you not fly the aircraft close to the water, as flying on the water's surface will affect the normal function of visual positioning, and the aircraft may fall into the water due to the impact on positioning accuracy.

Thanks for all the info. I have been a photographer for many years. Thought I try the drone thing. I have always done a lot of  waterfall photography so that’s what I wanted to shoot with the drone. Bad idea. I lost my first Mini 2 in a waterfall pool. Thought it was all pilot error. Then I got my second drone, a Mini 3 and it started to do some strange things when I flew over water. Guess I’ll have to concentrate on other subject matter with the drone. RN waterfalls on YouTube shows some of my first attempts at making a vid.

Very nice, btw there have been suggestions that the drone's VPS can sometimes lock onto and 'follow' foam etc. on the water's surface. I wouldn't necessarily let "over water" concerns put you off attempting to get waterfall photos via drone, just be wary and ready to give it throttle if you think it is descending. If a large waterfall also be aware the falling water may create air currents.

LV_Forestry Posted at 4-6 10:02
It's normal with these drones

All DJI drones come equipped with VPS, a technology that maps the surface below to help position the drone. When flying over water, however, light reflecting off of the surface can cause issues with this technology. Because of this, it’s best to maintain a height of at least two meters above the water. If you have to fly below this height for a special shot, we recommend you turn off the VPS to avoid any unstable actions by the drone. Caution: When you disable the VPS of your aircraft and the distance between water surface and drone is smaller than 2 meters, you should fly the drone with a low speed in your FOV (field of view). Also, the height needs to be adjusted frequently since the aircraft could possibly drift downwards. Be aware that the minimum height has to be above 1 meter when flying over water.

Hi,

Your link to that nice DJI video   is nice but ot correct for a MINI3PRO drone.

DJI FLYAPP drones cannot disable VPS botten sensor !

cheers
JJB

robnor1 Posted at 4-7 00:01
Thanks for all the info. I have been a photographer for many years. Thought I try the drone thing. I have always done a lot of  waterfall photography so that’s what I wanted to shoot with the drone. Bad idea. I lost my first Mini 2 in a waterfall pool. Thought it was all pilot error. Then I got my second drone, a Mini 3 and it started to do some strange things when I flew over water. Guess I’ll have to concentrate on other subject matter with the drone. RN waterfalls on YouTube shows some of my first attempts at making a vid.

Great picture.

Flying low over water is not a problem, will say it again it is not a problem.
I fly a lot above water and real low....
DJI remark about safe distance of 10 meter is.....BS.

BUT flying low over streaming water can be a issue, drone gets confused and difficult to keep horizontal positioning (driftin away with the water flow) and sometimes it will lower its height.

SO always keep a good eye on your drone, not watching the screen on the RC or device!

Plus be aware that if you fly real low and the VPS height sensor measures 0.5 meter (true or false reading *) AND you apply down stick : it will enter autolanding!  be very quick to UP stick to cancel this landing...   

* FALSE reading :  if the actual height drone <> water surface > 0.5 meter but the sensor 'measures' 0.5 meter.


Cheers
JJB

JJB* Posted at 4-7 02:44
Hi,

Your link to that nice DJI video   is nice but ot correct for a MINI3PRO drone.

It's not really the video that's interesting, it's mostly the text that explains the behavior of the VPS above water.

The adhesive tape technique no longer works?

robnor1 Posted at 4-7 00:01
Thanks for all the info. I have been a photographer for many years. Thought I try the drone thing. I have always done a lot of  waterfall photography so that’s what I wanted to shoot with the drone. Bad idea. I lost my first Mini 2 in a waterfall pool. Thought it was all pilot error. Then I got my second drone, a Mini 3 and it started to do some strange things when I flew over water. Guess I’ll have to concentrate on other subject matter with the drone. RN waterfalls on YouTube shows some of my first attempts at making a vid.

I lost my first Mini 2 in a waterfall pool. Thought it was all pilot error. Then I got my second drone, a Mini 3 and it started to do some strange things when I flew over water.
Flying over water is not a problem or the cause of drones ending up in the water.
Most of my flying (thousands of kilometres) is done over water.
The moderator's advice above is nonsense.

There are a number of other things that could have caused your issues.
Rather than giving up, you should find out what actually caused those problems and how to ensure that it doesn't happen again.
Analysis of of the recorded flight data is the way to do that.

Then why does the User Manual for the mini 3 and Pro say the same things the moderator said above? In fact the manual goes into even more detail. I find it hard to believe that DJI would just randomly make up stuff like that.

Do you think DJI is lying or just making stuff up or do they not know how these systems work?


Thats a serious question. Im brand new to drones and DJI, so I would kind of like to know. If you do - Id appreciate some links to hard facts if you have them. Thanks for your time.

LV_Forestry Posted at 4-6 10:02
It's normal with these drones

All DJI drones come equipped with VPS, a technology that maps the surface below to help position the drone. When flying over water, however, light reflecting off of the surface can cause issues with this technology. Because of this, it’s best to maintain a height of at least two meters above the water. If you have to fly below this height for a special shot, we recommend you turn off the VPS to avoid any unstable actions by the drone. Caution: When you disable the VPS of your aircraft and the distance between water surface and drone is smaller than 2 meters, you should fly the drone with a low speed in your FOV (field of view). Also, the height needs to be adjusted frequently since the aircraft could possibly drift downwards. Be aware that the minimum height has to be above 1 meter when flying over water.

LV_Foresry:
can we turn off the VPS with Mini 3? OR why did you recommend?

Larry3215 Posted at 4-7 22:37
Then why does the User Manual for the mini 3 and Pro say the same things the moderator said above? In fact the manual goes into even more detail. I find it hard to believe that DJI would just randomly make up stuff like that.

Do you think DJI is lying or just making stuff up or do they not know how these systems work?

Then why does the User Manual for the mini 3 and Pro say the same things the moderator said above? In fact the manual goes into even more detail. I find it hard to believe that DJI would just randomly make up stuff like that.
Unfortunately DJI documentation isn't great.
It's very sparse on important details and even has misinformation in some areas.

Do you think DJI is lying or just making stuff up or do they not know how these systems work?
I don't know but after 8 years, I'm used to the lack of quality in their documantation and moderators who seem to have no knowledge or experience actually flying drones themselves.
They just give the same cut and paste responses to questions.
Someone at DJI obviously knows, but things get lost in translation or low grade communications departments.

Thats a serious question. Im brand new to drones and DJI, so I would kind of like to know. If you do - Id appreciate some links to hard facts if you have them. Thanks for your time.
Just listen to the experienced users in forums.
The problem is being able to tell who knows what they are talking about from those that don't.
After a while you'll have a better idea.

relaxosmo Posted at 4-7 23:12
LV_Foresry:
can we turn off the VPS with Mini 3? OR why did you recommend?

It's not possible to disable VPS on any DJI drone that uses the DJI Fly app.

"DJI Fly app does not allow to deactivate the sensor."

Yes and so ? Be inventive guys, outdo yourself.


I don't even see what video you're talking about in the link I posted. There is a text and a GIF. Ah, maybe that's what you call a video. Then There is nothing I can do for you.

I rewrite it so that all the haters can understand:
What is interesting is in the text, "When flying over water, however, light reflecting off of the surface can cause issues with this technology. Because of this, it's best to maintain a height of at least two meters above the water."

On previous firmwares, hiding the sensor still allows takeoff. On the more recent ones, I don't know. Instead of insisting on crying that DJI Fly app doesn't allow deactivation, try it and we'll discuss it again. I don't have the mini 3 available to try right now.

And for the most haters, here is the link, all you have to do is order. If you need a tutorial for cutting and sticking the adhesive tape, go to Youtube.

https://www.aliexpress.com/item/1005001959233879.html?spm=a2g0o.productlist.main.27.240e6fdepd9cuA&algo_pvid=e1848f3e-5824-4a47-be20-0c6ba0c94f8a&algo_exp_id=e1848f3e-5824-4a47-be20-0c6ba0c94f8a-13&pdp_npi=3%40dis%21EUR%216.74%212.04%21%21%21%21%21%40212250c216809405993742167d0707%2112000030444837098%21sea%21LV%210&curPageLogUid=eVkdTH5yqEzs

Larry3215 Posted at 4-7 22:37
Then why does the User Manual for the mini 3 and Pro say the same things the moderator said above? In fact the manual goes into even more detail. I find it hard to believe that DJI would just randomly make up stuff like that.

Do you think DJI is lying or just making stuff up or do they not know how these systems work?

Because the forum is full of engineers who know better than the manufacturer what drones are made of.

The attitude of the drone above the water is normal in the sense that the design of the sensor causes this reaction.
What some users like Labroides mean is that it is not normal to deliver products with this kind of malfunction. And that's true.

You'll see many people say no it's not true because it's never happened to them. All waters are not alike, the reaction of the drone is obviously different depending on whether there is flow, waves...

Anyway, if you want the warranty to work in the event of damage, the only smart thing to do is to stick to the instructions in the manual.
Then if you really want you can try to hide the sensor and see if that corrects the fault. At your own risk !

LV_Forestry Posted at 4-8 00:20
Because the forum is full of engineers who know better than the manufacturer what drones are made of.

The attitude of the drone above the water is normal in the sense that the design of the sensor causes this reaction.

Because the forum is full of engineers who know better than the manufacturer what drones are made of.
The manufacturers know how drones work.
The manual is patchy and the moderators here, don't have any technical knowledge or flying experience.
They read from scripts and copy and paste "answers".

The attitude of the drone above the water is normal in the sense that the design of the sensor causes this reaction.
You have no idea what happened in the incident, or why, you can't say what happened or that something is normal.

What some users like Labroides mean is that it is not normal to deliver products with this kind of malfunction.
What I mean was what I said.
It's not at all normal for a DJI drone to descend when over water (unless the operator does something to cause it to).

Anyway, if you want the warranty to work in the event of damage, the  only smart thing to do is to stick to the instructions in the manual.
The manual has no useful information regarding flying over water.

Then if you really want you can try to hide the sensor and see if that corrects the fault. At your own risk !
Fault?
What fault?
No-one knows what caused the incidents mentioned.
No data has been supplied.
There's no fault that anyone knows of yet.

If the OP ever posts recorded flight data for his incidents, the actual cause es can be looked into.
Until then, further discussion is pointless.

Labroides Posted at 4-8 00:35
Because the forum is full of engineers who know better than the manufacturer what drones are made of.
The manufacturers know how drones work.
The manual is patchy and the moderators here, don't have any technical knowledge or flying experience.

Loss of altitude above water has been a known problem for several generations of drones equipped with this technology.  Of course it could be something else and the flight log could tell more.

It's visual positioning, real-time photogrammetry.  With surfaces such as water or even surfaces that are very uniform, the photogrammetry process has a hard time establishing enough points to estimate height.  The sensor works very well on standard surfaces like grass, asphalt... I'm sure that during the design nobody at DJI thought that someone would fly the drone close to the water.  

Afterwards, it's difficult to find a sensor that respects the size and power constraints of a device as small as a mini 3.

What DJI could do is implement the software deactivation of the sensor in the application,  and provide a guide to the scenarios with their associated settings as it exists on the M300 for the L1 payload in particular.  

LV_Forestry Posted at 4-8 00:59
Loss of altitude above water has been a known problem for several generations of drones equipped with this technology.  Of course it could be something else and the flight log could tell more.

It's visual positioning, real-time photogrammetry.  With surfaces such as water or even surfaces that are very uniform, the photogrammetry process has a hard time establishing enough points to estimate height.  The sensor works very well on standard surfaces like grass, asphalt... I'm sure that during the design nobody at DJI thought that someone would fly the drone close to the water.  

Loss of altitude above water has been a known problem for several generations of drones equipped with this technology.
The myth of altitude loss over water is due to misunderstanding of how the drone's systems work

It's visual positioning, real-time photogrammetry.  With surfaces such as water or even surfaces that are very uniform, the photogrammetry process has a hard time establishing enough points to estimate height.
That's an example of the misunderstanding.
The optical sensors of the VPS are for HORIZONTAL positioning.
They have nothing to do with altitude management.

Study the recorded flight data from over water incidents and find out what actually causes them.

Labroides Posted at 4-8 02:37
Loss of altitude above water has been a known problem for several generations of drones equipped with this technology.
The myth of altitude loss over water is due to misunderstanding of how the drone's systems work

Lab, I want to believe you, because what you write also makes sense. But I also want to believe what DJI tells us because when the drone approaches the ground, at least a vertical obstacle, something happens.  And this is completely independent of the barometer.  I don't know.  Once again if we could have access to the structure of the algorithm, things would be more understandable.

LV_Forestry Posted at 4-8 04:40
Lab, I want to believe you, because what you write also makes sense. But I also want to believe what DJI tells us because when the drone approaches the ground, at least a vertical obstacle, something happens.  And this is completely independent of the barometer.  I don't know.  Once again if we could have access to the structure of the algorithm, things would be more understandable.

what you write also makes sense.
That's because it's true and backed by evidence in the data.

But I also want to believe what DJI tells us because when the drone approaches the ground, at least a vertical obstacle, something happens.
Something happens ? .. and DJI told you that?

The optical sensors of the VPS are for HORIZONTAL positioning.
They have nothing to do with altitude management.

Are the 'cameras' in the VPS system not also the receptors for the IR emissions and, between the cameras and IR emitter, create/govern landing protection and descent speed when close to the ground? As per 4:28+ in

Labroides Posted at 4-8 04:52
what you write also makes sense.
That's because it's true and backed by evidence in the data.

when you approach a surface the drone hover at a certain height.  Then if you continue to input the Z- it will land on its own even when releasing the controls.  I'll try to find you a video or make one.

Sean-bumble-bee Posted at 4-8 05:30
The optical sensors of the VPS are for HORIZONTAL positioning.
They have nothing to do with altitude management.

thanks for the video Sean.  that's exactly what I had in mind, and tried to explain to Lab.

Sean-bumble-bee Posted at 4-8 05:30
The optical sensors of the VPS are for HORIZONTAL positioning.
They have nothing to do with altitude management.

Nice,

But he made a 'mistake'....

Put tape over both sensors, the downward vision sensor and the infra red sensor.
If he had only taped the infra red sensor (height measurement), drone was not in ATTI mode but using vision to horizontal stabilize, as the heigth sensor was 'disabled' he could fly under the table in a vision controlled way....

In the sofware the height sensor triggers at 0.5 meter. Pulling down from there drone will go into autoland.

If you hover at 30 meter height, apply full down and keep the stick down (do it sport mode!) ; you will see drone descent fast at first, within infra red sensor range it will start to slow down descent and will stop at 0.5 meter, while still keeping the stick down...after short delay it will autoland form there. (release stick, continue to autoland)

The question is if the downward vision is used when drone has good GPS reception. Text in various type manual write things down in a different way.....Flightlog shows vision "not used" if GPS "isUsed". But infra red sensor is always ON.


cheers
JJB

I recollect that a while back I selectively tried masking either the IR emitter or  the 'cameras' indoors, I seem to remember I did not like the results of either test indoors, I might be wrong and I am not going to try it again lol.

LV_Forestry Posted at 4-8 05:32
when you approach a surface the drone hover at a certain height.  Then if you continue to input the Z- it will land on its own even when releasing the controls.  I'll try to find you a video or make one.

What you tried to tell me was that the optical sensors are used to photogrammetrically detect height.
But they don't because they are used exclusively for horizontal position holding.
You never mentioned the infrared sensors which measure the height from reflected infrared light.

Now you are saying something about initiating landing by holding the left stick down long enough to overcome the resistance caused by low level flight as measured by infrared VPS sensors.
That's something that the operator does and not some known normal phenomenon as you suggested in your first post in this thread.

Hi all,

Who knows this ?

Does the infra red sensors 'signal' goes through thick black duct tape ??

Blocked the 2 infra red sensors on my MINI2 (not the 1 vision sensor)  and still got height info on the log.

cheers
JJB

Im not sure why there is all the arguing. Well, actually I am, but Im trying to be polite.

It obviously happened to the OP, and many others have reported the same behavior, apparently going way back, and on different models. Plus DJI says its true.

Maybe it would help to stop the arguing if a few of us go find a shallow puddle (or lake if you're brave) and just try this out under controlled circumstances. I thought about doing that today, but its raining way too hard. Around here puddles dont last long because the ground is so porous, but if I can find one - a puddle NOT a lake - I'll give it a go.

I wound up sending my Mini 3 back to DJI  to see if anything is wrong with it. Had several episodes over moving water. We will see what they say. Have only had it a week and a half.

Larry3215 Posted at 4-9 16:37
Im not sure why there is all the arguing. Well, actually I am, but Im trying to be polite.

It obviously happened to the OP, and many others have reported the same behavior, apparently going way back, and on different models. Plus DJI says its true.

Im not sure why there is all the arguing.
You're correct there.
Without knowing what actually happened, there's no point arguing about what people guess might have happened.

It obviously happened to the OP, and many others have reported the same behavior, apparently going way back, and on different models.
But there you go, arguing about what you imagine happened.
No-one has any idea what happened and no-one will until the OP posts the recorded flight data.
That goes for whatever others might have posted in the past.
The data I've seen from some incidents, didn't show drones mysteriously descending toward water.

Plus DJI says its true
What did DJI say is true?
Where/when?
I strongly doubt that DJI suggested anything of the sort
You have been taken in by misinformation.

robnor1 Posted at 4-9 17:30
I wound up sending my Mini 3 back to DJI  to see if anything is wrong with it. Had several episodes over moving water. We will see what they say. Have only had it a week and a half.

Are you interested to find out what happened and how to prevent it in future?
All it would take is to post the recorded flight data from the incidents and you could learn a lot.

DJI are very poor at explaining anything from flight data.
You will get much better data analysis and explanation from the users here that can read flight data.
If you want to learn from the incidents, you really should post data.
Not posting data is the way to learn nothing from the loss of two drones,

Labroides Posted at 4-9 18:05
Im not sure why there is all the arguing.
You're correct there.
Without knowing what actually happened, there's no point arguing about what people guess might have happened.

Plus DJI says its true
What did DJI say is true?
Where/when?
I strongly doubt that DJI suggested anything of the sort
You have been taken in by misinformation.

Seriously? More than one post - including one from me that you replied to - mentioned that its in the Owners Manual.


Ok one more time

Larry3215 Posted at 4-9 19:54
Plus DJI says its true
What did DJI say is true?
Where/when?

Seriously? More than one post - including one from me that you replied to - mentioned that its in the Owners Manual.

Yes, seriously.
This is the issue discussing with people with very limited understanding of how their drone works and come to invalid assumptions.
The optical sensors of the VPS are for horizontal position holding.
They have nothing to do with vertical stability.
That's what the DJI manual is referring to.
The VPS can't easily lock onto anything when the surface below is water.

Show me the flight data from just one of these incidents you are so sure about and I'll show you what actually happened.
One more time ... DJI drones don't have any problem maintaining height when above water.
Suggestions that they don't are uninformed misinformation.

robnor1 Posted at 4-9 17:30
I wound up sending my Mini 3 back to DJI  to see if anything is wrong with it. Had several episodes over moving water. We will see what they say. Have only had it a week and a half.

To be honest and I do not think the return to DJI was necessary.
Irrespective of the reason and whether or not VPS etc. is the culprit there are enough anecdotal threads about to suggest that care is needed when low over water.
I have flown a Mavic Mini down to probably 3ft, or less, over a salt water lagoon to look through the pipes that connect the lagoon to the sea. As I remember I had a couple of possibly false alarm " I think it's descending, give it full throttle" climb outs but in the end I got the look.

You just need to watch the drone like a hawk and be ready to respond, I'd suggest it would be better to watch the drone with your eyes not the screen view, if really low the and watching the screen the video lag and your reaction time might be 'fatal'.

There are also several threads which suggest that a drone with VPS can, in some unknown circumstances, follow foam, flotsam etc. and maybe even ripples etc. on the water's surface.
I have tried 'hovering' a Mavic mini low over a distinctive object on the ground and then, with my fingers nowhere near the joysticks, dragging or moving the object. Sometimes the drone follows the object, sometimes it does not, I can discern no pattern to whether or not it will follow the object.

All these suggest fly with additional care when low over water. Better safe than sorry.