I was wondering whether I could for example calibrate my Inspire at ground level, take it up to a parking lot and then fly it from there? After making sure the IMU readings are fine and all.

compass and steel in concrete=bad idea.
  if you are not moving too far the compass cal. should be ok..i have friends with beta units that drive all over and don't calibrate.
i would not myself..but then i am just a poor boy with a rich toy.
  if you are near metal rebar,cars etc. you could have trouble. not sure if flying low using sensors would be ok though..afraid to try myself.

i would do it where you plan on taking off from.  i calibrated my bird in my basement and had to do the compass in the front yard again.  

s.s.gibbs1.emai Posted at 2015-1-20 12:53
compass and steel in concrete=bad idea.
  if you are not moving too far the compass cal. should be o ...

Its literally the following:

Calibrate my bird on ground level.

Walk 10 metres to garage elevator. Go to 7th floor. Walk 5-7 metres. Check for compass readings. Check sensor readings. Take off.

I don't want to calibrate it on a parking structure with reinforced steel but does my plan sound like a good plan? I ask because parking structures represent a great number of tall buildings with a wide roof that I have access to.

I've calibrated and flown on the 4th floor of a subterranean parking garage without issue. DJI also flew inside of the LVCC during CES. It's a very large steel building. There's more steel in that building than rebar in a concrete parking garage. I don't know where they calibrated but you're supposed to calibrate at the location you're flying.

Joola Posted at 2015-1-20 13:52
I've calibrated and flown on the 4th floor of a subterranean parking garage without issue. DJI also  ...

I assume there is a "give or take"?