I've been flying drones for a while now, however, this is my first DJI. I recently tried to fly inside a small valley (under tree cover) and didn't have GPS. I was trying to fly "line of site" as I had complete visual of the device and the waterfall I was filming, however when I took off from a small cliff over looking the waterfall, I couldn't do anything but fly down as the device didn't "know" where it was and wouldn't go up. Any advice for flying in a wooded area or anywhere that has no location signals? Any help would be great, thanks.