Holding exact height low above water..

[phigun]

Hey guys I just tried to get a specific Video shot yesterday flying over a river at maybe 2meters height and the 4Pro was not able to hold the height at all. It constantly lowered or raised its height rapidly and I could not get this sorted out and was worried that it will even hit the trees above and in the end I had to go home without the shot I was looking for.
As I had never experienced something like that before I am curious for any experience flying low above Water, any ideas what I could try out next time, is it even a normal behaviour ?

Here is a still of the exact scenery:

 

[msinger]

If you turn off the downward sensors, the hover might be a bit steadier. However, it's never going to be as steady in scenarios like this where the downward sensors are not able to accurately detect the ground.

 

[phigun]

If you turn off the downward sensors, the hover might be a bit steadier. However, it's never going to be as steady in scenarios like this where the downward sensors are not able to accurately detect the ground.

Thanks will sure try that out interested to see how much more stable it will be without them if still save enough to fly in such a narrow space.

 

[MaxHam]

Switching off downward sensors over water seems to be a must. If phigun has enough satellite reception in this forest environment - would P-GPS be available and solve his problem? Somewhere I've read that below a certain height GPS (below 3 meters or so) is no more active and VPS kicks in.

 

[Roamer105]

Hmm... no problem doing this with my P3P....(with ground sensor turned on)

 

[DanMan32]

VPS isn't recommended over water though that's mainly for horizontal stability since vision is used for that. Think of an optical mouse on a glass table. Ultrasounic is mainly used to determine height.

 

[jmy7213]

You are never going to get completely stable flight if you are low near the water. Even if you have all the sensors off, the barometer sensor is still going to go nuts due to it reading moisture which is constantly changing, as water is never completely still. You just have to be quick on the stick when you fly low to water.

 

[Roamer105]

No problem here: check the middle part of this video:

 

[alokbhargava]

It's true that ground sensors should be disabled if there is no steady pattern below or if the water has wavy pattern due to the wind. Problem gets worst if there is no GPS satellites locked. If you are not taking the shots directly below and if you can reach the point below the craft, a floating mat or something like that could be placed there to let AC control horizontal and vertical positions correctly.

 

[arnok9010]

No problem here: check the middle part of this video:

Awesome video. When I tried to do similar at the beach with my P4 it constantly tried to suck itself into the water. It almost required full up stick to stop it crashing. Did you turn the downward sensors off ?

 

[phigun]

No problem here: check the middle part of this video:

Mhm did you turned the downward Sensors off or are they all on ? Indeed yours looks quite stable over Water in this flight..

 

[Roamer105]

Sensors on. Never had a problem over water. I have another video where I am chasing water birds, really close to water and surprisingly stable height over the surface.

 

[KevMo Photog]

Sensors on. Never had a problem over water. I have another video where I am chasing water birds, really close to water and surprisingly stable height over the surface.

Fabulous location your flying there Roamer! Didn't look like you were really that close to the water in this one though. Still looked like you were at least 15ft if not more. But I get down to about 5 or 6ft without too much prob. If I want closer I def have to turn off VPS!

 

[Roamer105]

You are correct I was between 10 to 15 feet above the water. Awesome lake - so clear it is amazing.