I came across a web service called Litchi - flylitchi.com - where you can plan waypoint missions, mainly for doing site shots and videos - but it appears not so much for mapping a polygon.
Cool ting is you can plan your mission in a browser on a PC, save it, then execute it from the Litchi ap (do cost around 20 USD).
During planning, you can export a 3D KML model and view it in Google Earth - ensuring you are free of obstacles. A lot nicer than pecking at a smartphone screen - especially if out in the cold. Example 3D model. Look for Litchi demo’s on youtube or phantomfilmschool.com
You can assign multiple actions to each waypont, like:
- Wait 5 secs to stabilize
- Take 3 photos at POI 1
- Start Recording
Then drone proceeds to WP 2 and executes assigned actions etc.