Terrain Following on walnut trees

Hi. I want to follow the terrain with Benewake TF 02 Pro. But it is a walnut land that contains 8x8 or 8x4 walnut trees. Copter should fly 2 meters above walnut trees. The problem is when copter sees the ground from between trees it will fly 2 meters above from the ground. It can cause a crash But I want to fly copter 2 meters above from trees.

You could try lidar come avoidance with bendy ruler. OA_BR_TYPE = 2: Vertical BendyRuler

See here:

https://ardupilot.org/copter/docs/common-oa-bendyruler.html

I don’t understand clearly that what are the differences between terrain following and bendy ruler.

The bendy ruler should “jump” the obstacle