so this is partly venting and partly trying to figure out if i did something wrong or if this is just one of those things. was doing a post-storm insurance inspection on a commercial flat roof today, big warehouse maybe 400 feet long, and everything was going fine. had my mini 3 pro up doing a grid pattern at about 80 feet, overlap was set to 75% for the photogrammetry model the adjuster wanted.

about halfway through the battery the aircraft just starts drifting toward the rooftop HVAC units on the north end, like the positioning just got mushy. wind was maybe 8-10mph nothing crazy. i took manual control and got it back no problem but i was pretty close to one of those units before i reacted, closer than i was comfortable with.

im wondering if it was the interference from all the HVAC equipment or maybe GPS was degraded because of cloud cover, it was pretty overcast. the visual positioning wouldnt do anything useful at 80ft anyway. just felt weird because ive done probably 30 of these roof jobs and never had that happen. the mini 3 has been solid for me. maybe i got complacent with it.

yeah large metal rooftops with a bunch of HVAC units running are basically an interference nightmare. those compressors and motors can mess with your compass readings more than people expect and on a flat featureless surface GPS multipath from the roof itself can cause some weird positioning behavior. 80 feet is also kind of in that awkward zone where VPS is useless but youre not high enough to have a really solid GPS lock in a degraded environment. not saying thats definitely what happened but id bet on some combination of that.

i've started doing flat commercial roofs at closer to 120-150ft for the grid and then doing a lower manual pass for close-up detail shots separately. takes longer but the aircraft behaves more predictably at altitude.

this is why i moved off the mini series for commercial inspection work tbh. the smaller aircraft just have less authority when things get weird. got a phantom 4 RTK for mapping jobs now and even though its older the positioning accuracy and the way it holds in marginal conditions is just more confidence inspiring. mini is great for what it is but thats not really its intended use case imo