While I was working on tweaking some configuration settings in the DJI Go App (while inside my house) to prepare for my next (outdoor flight), I noticed the following once the Mavic had completed its initialization procedures: (1) The Forward Vision System Status icon is red (2), The clearance is listed as 0.3ft (and is red) (3) The Obstacle Detection Status bars are not visible (4) The craft is in ATTI mode.  

Now, while I'm not intending to take off indoors any time soon, I was curious why the craft wasn't in OPTI mode, and why the vision sensors seemed to be unhappy (although they all report normal in the system status, and have seemed to be operating correctly in outdoor flight).

So I played around a little bit, and I noticed that as soon as I lift the craft (it was not armed) about 18 inches off the ground, the Vision System Icon will return to normal status, the Obstacle Detection Status bars will appear and report correctly, the clearance will listed as 1 ft (instead of probably 18 inches) and not be red, and the aircraft will switch into OPTI mode.  Moreover, as I slowly lower the craft towards the ground, when I get to about 1-2 inches above the ground, everything will revert (Forward Vision Status Icon Red, Obstacle Detection Bars disappear, 0.3ft clearance in red, ATTI mode).

So with this setup, I can only conclude that I would not be able to take off in OPTI mode, but would possibly achieve it once airborn.  As I haven't flown the aircraft too many times, I haven't noticed whether the vision system has indicated red on the ground outdoors before - I've always had strong GPS, so no ATTI mode to really alert me to this.  I usually scan the instruments fairly carefully before taking off, so if I had to bet, I would say the vision system icon was not red.

Finally, I was inside with what I consider reasonable lighting, over a wood floor that obviously has a reasonbly textured, non-repeating pattern.

Any thoughts on why I am seeing this behavior?  I don't like to calibrate things unless they need it, but I wonder if a downward vision system calibration might be the root cause here (aircraft thinks its below the ground).

My plan is to check if I see the same behavior outdoors, and wait to see what the DJI folks on this channel this with respect to Vision System calibration.

Adding pictures (they are in reverse order, the top one is after I lift the Mavic off the ground).

Have you attempted to calibrate both your imu and vision positioning sensors? That could solve your problem.

DJI LA Support Posted at 2016-11-19 12:49
Have you attempted to calibrate both your imu and vision positioning sensors? That could solve your  ...

I have not attempted to calibrate the IMU or positioning sensors yet.  As above, I didn't want to calibrate anything other than the compass if not necessary.  I'll take a look at calibrating the Vision sensor next.  The manual mentions being able to perform a "Quick Calibration", but I can't find that anywhere in the DJI Go App (iOS 3.1).  Can you confirm if this manual is accurate and, if so, where in the App I can find the quick calibration for the Vision system.