(image taken from https://www.pgc.umn.edu/data/arcticdem/)
I would like to say a big thanks again to ArcticDEM project (https://www.pgc.umn.edu/data/arcticdem/). Using their elevation data it is possible to fly drones safely in parts of the globe not covered by "standard" sources of maps and elevation data. ArcticDEM covers a huge area north of 60°.
Look at this Google Earth view - a random point somewhere in Norway, with coordinates 69°45'31.73"N 19°52'0.85"E. According to Google data, the elevation here is ~335m.
Here is the same point in UgCS (without ArcticDEM)
Lets do 5 seconds of magic in UgCS:
That's all. Now in the same point we have an elevation of 352m.
It may not seem like a big difference (~17 meters), but even such a small error can be disastrous if you fly a route like that with a magnetometer attached to a rope.
It is totally worth spending those 5 extra seconds and have a bit more confidence...
In some areas I have observed a difference of up to tens meters (Greenland, Svabald, etc).
Very important: this online source of ArcticDEM data for UgCS was build using a 32m grid. It is enough for most missions and is much better compared with SRTM, but you should be careful in case of very low altitude flights.
Another important note: in same places ArcticDEM can have voids and processing artifacts, especially over water near the shore lines. So please check your routes carefully...