Yesterday, when I started the drone, these sentences continue to appear.
“Terrain: clamping offset 28 to 15”
a scene of first sightings
When the wind blows while hovering, it goes down to the floor.
What is problem?
Hi Park !
I encountered to this problem too, and so confused.
If you already solved this problem, Im so happy to know the method of solving.
did you solve? I am getting trouble same problem
NOT YET 
But it doesnt occur every time.
HC-SR04 Ultrasonic does the same thing. I’m struggling too, I’ll write if it gets fixed.
Wind can skew your barometer readings, especially if it’s not well shielded behind some foam or other physical barrier.
Have a look here for software compensation:
https://ardupilot.org/copter/docs/airspeed-estimation.html
Whatever the cause, the TERRAIN_OFS_MAX parameter is being exceeded, causing the messages to occur.
TERRAIN_OFS_MAX:0
If parameter setting is made, this warning should not be received.
What Version you using?