I cannot find any how to's on the Hangar site for using the app with the Spark. Should it be in Sport mode or not, how does one halt a mission if things go awry? Any input would be greatly appreciated.
The controller should be on normal flight mode / P, you slide the switch to Sport mode if you need to take control in an emergency.
Basically you close DJI GO 4, load the app, once it says you are good to fly (GPS mode etc) you can launch by pressing the 360 Photo button, it will fly to 300 feet and take the pictures. You will then be asked whether you want to continue flying or land.
Alternatively you can load the app, take off, fly to the location and altitude you want to start from, press the button '360 Photo' and you will be asked whether you want to remain at current altitude or go to 300 feet.
You can also switch to the app mid flight, leave the Spark in a hover, close DJI GO 4 fully, load Hangar 360, take your pictures. Close Hangar 360, load DJI GO 4 and continue flying.
Whatever option you use once the images are taken you will be prompted to download the pictures from the Spark to the application, once downloaded you are then prompted to upload them to the internet so that Hangar 360 can process the images. This can be done later.
I posted an example in less than ideal lighting conditions here
Hangar 360 App - 360 Photos with Spark?