Vision and radio communication obscured?

[bronzeo]

I haven't flown yet, but have a desire to take a drone up some bends in waterways (creeks, rivers, etc) a few feet off of the water and under overgrowth tree canopies just for photos and explorations sake..... I have read the radio will communicate through some trees, but should it lose its signal, how does the drone RTH if there is a tree canopy above it 20 feet? Many of our streams in the Ozarks are like this. (Am I limited to line of sight?) I'm experienced with RC boats, but they don't have to fly out and can swim on their own......

 

[rjwmorrell]

This is about as high risk as you can get. Most DJI drones I'm familiar with warn against flying lower than 3m (about 10 feet) above water for good reason, the downward vision system has a hard time fixing position or detecting the surface to avoid a collision, and obstructed Control Station signals could result in an initiation of the auto RTH or auto land.

I'd recommend using extreme caution.

 

[Phantomrain.org]

You might consider getting the Rescue Jacket as there is going to be a learning curve and the Rescue Jacket can help you with staying low on the water and landing on it if need be.

Phantomrain.org
Gear to fly in the Rain. Land ont the water.

 

[Cafguy]

Yes you are limited to line of site without a spotter and even then, you still have to be able to see the drone once you look up from the screen or goggles. You can set your drone to hover rather than land BUT Then there's the water - that can confuse your drone sometimes you can fly over water just use some caution.

 

[Yorkshire_Pud]

You set the failsafe option to "hover", page 52 of the manual etc.
and pray that it
a) holds its height, and
b) you get close enough to regain control BEFORE the low battery RTH kicks in.

Otherwise most likely wave goodbye.

I wouldn't recommend such flights.

 

[mavic3usa]

DJI Avata is the right tool for the job, no worries:

 

[Mazdaman323lx]

Put a go pro or insta 360 on one of your RC boats . Job done

 

[bronzeo]

Put a go pro or insta 360 on one of your RC boats . Job done

have tried, but get some funky photos, kind of like taking photos from the ground laying on your back.

 

[Droning on and on...]

As @Yorkshire_Pud said, the technical solution is to set RTH to hover.

However, in a mission like this, planning more important. If you lose signal and it stops and hovers, you're going to need to get back in range and reconnect to get your drone back.

So, plan ahead of time exactly what you're route is going to be. Use a map. Plan how, along that route, you are going to move closer to where the drone is hovering, to reconnect. Consider the entire path, and several reconnect/recovery locations.

Just in dealing with the disconnent issue, a lot can go wrong. How long is it going to take you to get to where you reconnect? If it takes longer than your remaining battery, you're going for a bath.

That's all the stuff you can plan for, and reduce risk. Other stuff, like VPS confusion low over moving water, is just something you'll have to live with, and hope it doesn't drift into a tree branch or something while "hovering" disconnected.

To counter that, use an Avata, or fly with prop cages if available for your model... I think it's an available DJI accessory for all the Mini models. Example, the Mini 3:

 

[bronzeo]

I was under the assumption that at low speeds, the drones were very controllable like for hovering and slow maneuvering. Do they not judge off of water too well? Boats are hard to hold as they float in circles when not under power. I will be flying a Mavic 2S, so hopefully good controlability.

 

[rjwmorrell]

I was under the assumption that at low speeds, the drones were very controllable like for hovering and slow maneuvering. Do they not judge off of water too well? Boats are hard to hold as they float in circles when not under power.

They are not good at detecting water and computing it as a surface, it confuses their visual position sensors. That means it will drift, potentially, if the GNSS signal isn't great. As for altitude, water again is not great for detection and it will be relying on barometric pressure mainly.

The manual contains warnings about this.

The good news is, 3m off the water is sufficient for most shots, though I suppose that applies better to wide open water when, say, zooming towards a beach or coast... following a river at 3m may not be as impressive. But for my money, the stability is worth it, even at 3m altitude. You can't get stable shots like that from a boat without expensive rigs.

 

[bronzeo]

DJI Avata is the right tool for the job, no worries:

Yes, this is exactly what I hope to do, in not so tight of quarters..... These Vids are amazing.....

 

[Droning on and on...]

I was under the assumption that at low speeds, the drones were very controllable like for hovering and slow maneuvering. Do they not judge off of water too well? Boats are hard to hold as they float in circles when not under power.

The VPS system is reliable, even low over moving water, most of the time, but can be fooled.

It's gotten better over generations, seems to get out of the way better these days when there is control input. Years ago people now and then had wild responses to stick movements.

We used to be able to turn it off, which helped a lot in situations like this.

 

[bronzeo]

DJI Avata is the right tool for the job, no worries:

How is this Avata model not losing radio contact? It looks like it would be blocked badly according to info I'm reading....

 

[Mazdaman323lx]

Personally would'nt risk it , 10 feet above water , 10 feet under tree canopy , no signal to RC .Not a good place to be .Plus with the tree canopy above you you may even go into atti mode which will cause the drone to drift in the breeze rather than hold its position . Could be a expensive project purely for exploration sake. Be cheaper to hire a canoe ?

 

[Yorkshire_Pud]

I was under the assumption that at low speeds, the drones were very controllable like for hovering and slow maneuvering. Do they not judge off of water too well? Boats are hard to hold as they float in circles when not under power. I will be flying a Mavic 2S, so hopefully good controlability.

That depends on what is controlling the drone's position holding.
There are two systems that DJI drones commonly use when low. One is GPS, the other is the VPS system.
Under a tree canopy the drone may not see sufficient GPS satellites to establish its position. If that happens then the drone has to rely on VPS.
VPS position holding is, under suitably conditions, actually better than GPS position holding but VPS needs good light and a suitable surface over which to fly/hover.
If the lighting is too poor and the GPS insufficient then the drone will switch to ATTI mode where the drone will NOT hold position and, unless you give suitable commands via the joysticks, it will be blown about by any wind. I do not know what happens if the lighting is good but the surface is inappropriate.
Additionally,
1) there are stories of drones following water flow patterns or foam or debris on/in the water, presumably via VPS.
2) It has just occurred to me that you should check the drone's manual to see what happens if the drone loses connection when it does not have a GPS lock, I think some LAND.
3) That I know of, there is no such DJI drone as a Mavic 2S. There is a Mavic 2 Pro/Zoom, a Mavic Air 2 and a DJI Air 2s. Some or all of those have an auxiliary light on the bottom of the drone which can aid VPS but I have no idea what will happen if the drone is relying on VPS and the light switches on over water.

I will say it again ...... I would not fly such a flight. I think you stand a significant chance of losing the drone.


I have seen Avatar videos and to be honest I have no idea how the drones do so well in such conditions.

 

[bronzeo]

all good info, thanks.

 

[Droning on and on...]

The formula for how DJI drones do positioning is pretty simple... If there is sufficient ambient light, the VPS system is used below 30 or 45 feet AGL, depending on the model, and with GPS above that.

VPS uses a technique called "Optical Flow" analysis of an image stream to detect horizontal movement. It's very precise compared to GPS, and is the only way your drone hovers in front of you rock solid without moving.

 

[mavic3usa]

How is this Avata model not losing radio contact? It looks like it would be blocked badly according to info I'm reading....

Just get DJI care refresh and take your chances. I'm not a risky flyer but the distances I have achieved are amazing to me so I can only imagine if I pushed it hard. To be fair, about videos, there *could* be some movie magic happening. If you stand in one spot and you fly a far as you can in one direction, when you turn around and come back towards yourself and start recording at that point, you can probably go *twice* that distance (when you pass by and keep going in the other direction). So there's that. But still, the penetration is amazing.

For example, a big circle or mostly wandering like these:

Pretty cool:

My all-time favorite FPV video:

 

[Torque]

How is this Avata model not losing radio contact? It looks like it would be blocked badly according to info I'm reading....

I fly the Avata, the DJI FPV, Mavic 3, Air 3 and Mini 3 Pro on a regular basis. Of all my drones, the Avata is the one to lose video feed at the shortest distance. It is the perfect drone for the job, but once out of sight of your controller (i.e. a forest between the two because you followed the bend of the river) I would not trust it. For close exploring you should be ok.