we have a very large difference in altitudes in a mission, we were told to do the flight parallel to the surface but we dont know how to pragram that kind of flight if anyone knows how to do it we will be very grateful
You need to have a read of this article as it helps you plan a project beforehand. Enjoy!
What kind of UAV are you using? The manufacturer might know. With something like the Pixhawk you can manually change the altitude of the mission waypoints to fly parallel to the surface. It also has “terrain following” but it is very coarse. I think because it is based on Google Earth terrain data so the manual waypoint altitude is best.