Since sports mode disables GPS would that be the safest way to fly where GPS signal is hit or miss? Control is not my worry it is the drone going in and out of GPS and possibly doing wacky things. There is a concrete building I would like to film in but there is some obstacles and my only worry is that GPS will go on and off and make the MP act erratic. Also is there a way to disable the automatic landing the MP does from 2 or so feet?
Personally, unless I were in a
very spacious environment - like filming a monster-truck rally kind of indoor event inside a large stadium-like setting - I would not consider flying the Mavic indoors in Sport mode ever. Too much power/speed at the sticks, much greater braking room needed in Sport mode plus, as you mentioned no GPS to help you out with aircraft control or positioning. All things to be considered. However, when considering you want to film
inside a concrete building - which probably has metal rebar rods, wire mesh, etc., within the concrete, all of which are GPS signal blockers - not to mention the signal-blocking nature of concrete itself, it's doubtful if you will get much in the way of GPS input anyhow. Best way to find out is to take your gear to the desired film location, power up everything, and see exactly what GPS signals you receive there.
I would fly in an average indoor environment in Tripod mode only, giving you slower aircraft speeds to contend with; less prop backwash to deal with during a confined indoor flight; much smoother flight and camera action for better images; plus the additional aid of having Optical Guidance engaged. When using Optical Guidance (the encircled icon will appear on your controller when it is engaged) the Mavic's bottom cameras and sensors detect the floor patterning and will maintain position relative to that realtime input being received instead of using GPS. However - and I may be wrong about this - I think a general concern when flying the Mavic indoors is IF GPS kicks in suddenly and overrides your flight control, which would be a bad thing. I don't
think there is a way to lock in on Optical Guidance, but if I am wrong someone please correct me so I will know, too.
But as far as I understand, provided there is adequate lighting, the floor surface being read by the Mavic's undercarriage cameras and sensors is not too shiny and has enough patterning to stimulate the sensors, and Optical Guidance is engaged, indoor flying with the Mavic is doable. I've read and seen videos that attest to this, one video, I believe, from DJI itself. One of the reasons I purchased the Mavic was because of my desire to capture indoor images (I have very high ceilings in my house with a very open, spacious floor plan and envisioned interesting camera shots during Christmas, birthdays, family gatherings, etc.); however, I haven't quite gotten up the nerve yet to try it. When I do I think I'll install the prop guards I bought for my Mavic but have never used just in case I do bump into a wall or something and a silly crash could be avoided.
Other folks with more experience than I have may have better answers for you. Good luck with your planned project. Sounds interesting. Consider posting some of the footage here you come up with to give all of us something different to see and learn from. Safe flying, good filming and photography.