Hello guys,

What would you consider as best settings to fly over water ?

- For instance, because of the MM camera viewing the ground even at higher altitude, I wonder if a polarized lens ( not on the gimball camera, but on the ground camera ) , could make the camera more able to see rocks and algaes through water, thus would fly safer ?

- Would atti mode ( a piece of tape over the ground sensor  ) prevent the MM camera to stop viewing the ground and therefore messing up the MM brain  ?

- Is GPS mode the best mode over water ?

Cheers

Generally I try to fly higher than the downward facing sensors are able to work. If I am low and the bird starts to get away I will generally raise altitude asap.

If your flying over water that has little to no movement or it is
reflecting don't hover to low. There are no best settings, just smart flying
when it comes to flying over water. Try flying the shoreline first and gradually
fly farther out over water to build your confidence.

Why is flying low above the water is dangerous for the drone if it is in P-mode so the GPS is the master?

Just don't fly low and you should be fine.

Just remember if your within 20m of home point RTH will land without attempting to return

Just fly, as long as you have plenty of sats.

Dr. Alex Posted at 5-5 08:08
Why is flying low above the water is dangerous for the drone if it is in P-mode so the GPS is the master?

GPS is actually never the master of altitude. The IR sensors are below a certain height, and then the barometer sensor is after that. The GPS is the master of location, unless your drone is underwater, and then it is the master of nothing. It sleeps with the fishes. Also, the downward camera is the master of position when you are below a certain height as well.

It isn't the camera, it is the two IR sensors. About the only thing you can do is put tape over them. Let us know how that works out. I fly over water, but at 100 feet+.

Using an CPL filter above the camera is surely tricky, not only there's the two IR diodes on the sides but the PL will only work for certain orientations, and if it worked (canceling the surface reflections) it might make things much worse... it might end up picking the bottom of the water body you're flying over, not the surface, thus providing a false (increased) reading of the altitude, quite dangerous stuff...

Settings don't matter so much. If you are moving you won't have any issues. If you stop the drone can just lower itself into the water by itself. It's because the downward sensors used to maintain position cannot work with surfaces such as water. I flew at a boat dock. I was hovering just under 5m near some boats adjusting the exposure when I noticed the image dropping. I quickly lifted the drone to a height where it would maintain position. You just have to be careful. If you are flying forward or backward it isn't an issue. If you stop low and hover you can find it lowers automatically sometimes. The other option is to not fly lower than 5 or so metres. Above that it hovers fine I have found. It's just close hovers that it struggles with. All DJI drones have the same issue, it's not unique to the mini.

Keep in mind that there are two systems on the bottom, a camera and the downward sensors. They do different jobs. The down sensors work by reflecting their IR light off the surface to determine close altitude. It may be that clear water would be worse for detection and polarized filters might cut through that surface. Being 10 feet over very clear water 20 feet deep might read as 30 feet altitude. All major guesswork here ;-)

Interesting conversation.

So if I understand correctly, to fly safe, I should try to force the IR sensor to comprehend water surface as if it woud be land, so totally the opposite effect of a CPL.

But then most of you here say that flying higher are giving the best results. But by flying higher, that 's how you see the sea bottom better.

Any engineers around ?