Noticed last night flying around a friends well lit backyard at 6 to 10’ that the Mini will drift horizontally and climb when over the swimming pool. Once over solid ground it goes back to rock solid.
I don’t recall this behavior with any of my prior DJI aircraft.
Is this a known problem?
Btw I flew yesterday morning 3/4 of a mile out over the coast and no problem at 100’ over the ocean.

Could be too close to the pool. The MM has the same kind of setup as the Tello with the visual positioning sensors. I have flown my tello over small bodies of water, but I have noticed that if I am not very high over it, it is a little jittery. I've read it has something to do with it being able to see the water moving and having a hard time trying to focus on one spot to maintain position. May not be the case as I don't have my mini yet to try it out but just a thought.

JodyB Posted at 11-16 07:16
Could be too close to the pool. The MM has the same kind of setup as the Tello with the visual positioning sensors. I have flown my tello over small bodies of water, but I have noticed that if I am not very high over it, it is a little jittery. I've read it has something to do with it being able to see the water moving and having a hard time trying to focus on one spot to maintain position. May not be the case as I don't have my mini yet to try it out but just a thought.

Thanks Jody, that makes sense.

Alan E Posted at 11-16 07:25
Thanks Jody, that makes sense.

No worries man. Hopefully the info helps.

I had that also with the mavic platinum. The problem is that the bottom vision sensors cannot detect proper underground, like swimmingpool has a monoteous underground blue when flying low. Also for example snow or sometimes grass. If you check the manual its written in there that flying over monoteous underground can cause problems if flying low . So it can mixup the bottomsensors

dronie1965 Posted at 11-16 07:39
I had that also with the mavic platinum. The problem is that the bottom vision sensors cannot detect proper underground, like swimmingpool has a monoteous underground blue when flying low. Also for example snow or sometimes grass. If you check the manual its written in there that flying over monoteous underground can cause problems if flying low . So it can mixup the bottomsensors

Yep, the manual has a section for those surfaces, many to actually take in to consideration since if it cannot see with the bottom sensors it may try to go up. I place it here for a quick reference:

- The Vision System may not function properly when the aircraft is flying over water or snow-covered areas.
- Note that the Vision System may not function properly when the aircraft is flying too fast. Fly with caution when flying at over 10 m/s (32.8 ft/s) at 2 m (6.6 ft) or over 5 m/s (16.4 ft) at 1 m (3.3 ft).
- The Vision System cannot work properly over surfaces that do not have clear pattern variations.
- The Vision System cannot work properly in any of the following situations. Operate the aircraft cautiously.
a. Flying over monochrome surfaces (e.g., pure black, pure white, pure green).
b. Flying over highly reflective surfaces.
c. Flying over water or transparent surfaces.
d. Flying over moving surfaces or objects.
e. Flying in an area where the lighting changes frequently or drastically.
f. Flying over extremely dark (< 10 lux) or bright (> 40,000 lux) surfaces.
g. Flying over surfaces that strongly reflect or absorb infrared waves (e.g., mirrors).
h. Flying over surfaces without clear patterns or texture.
i.  Flying over surfaces with repeating identical patterns or textures (e.g., tiles with the same design).
j. Flying over obstacles with small surface areas (e.g., tree branches).
- Keep the sensors clean at all times. DO NOT tamper with the sensors. DO NOT use the aircraft in environment with dust and humidity. DO NOT obstruct the Infrared Sensing System

There is a similar problem with auto focus on cameras. If there aren't any contrasty targets, the autofocus can hunt backwards and forwards trying to establish distance. Similarly, a featureless surface, can confuse any visual rangefinder. I think most decent drones rise in the air if they are in doubt about what is underneath as a safety measure.

Hello and good day Alan E. I am sorry for the trouble and thank you for reaching out. It is not recommended to fly the aircraft close to the water. When flying above the water, the vision system of the said drone  will turn off automatically, if the vision system is affected an accident might happen. Thank you for your understanding and support. Please refer to Juliflash post #6 on how to utilize the vision system of your drone properly and for additional reference I will be posting a link where in you can check the User Manual for the DJI Mavic Mini. Thank you.

https://dl.djicdn.com/downloads/ ... _Manual_v1.0_en.pdf

Awesome support everyone, thanks!

Alan E Posted at 11-16 10:37
Awesome support everyone, thanks!

You are very much welcome Alan E. We are all glad to help you. if you have any other inquiries or concerns with DJI. Please feel free to post it here at DJI Forum. We are all here to help and assist you. Have fun and happy flying always.