These appear to only unlock when you are either snowboarding or skiing ie. on the ground. Wingsuits and paragaliding do not unlock these even if you are directly above them.
I found this easiest when after completing a race or freestyle event and just continuing on past the finish line. If you keep going you will undoubtedly unlock a Point of Interest almost straight away due to where the finish of most events end, near the little villages.
If you are still struggling go to mountain view and pick any drop zone. Then have a look around and head towards villages you can see or deep valleys. Most of these are Points of Interest and are unlocked by just travelling through them.
Hope this helps. Any feedback appreciated