Hey Tobias!
I’m playing with your terrain system, and it seems that there is some sort of problem in the way it is computing the mesh inside/outside of the field of view:
Investigating a bit, i reach the conclusion (I can be completely wrong, by the way) that it is some sort of precision problem. It seems to be related with the absolute position of the camera
Bye!
Pepe
P.S. You can check it with the following example:
github.com/sanguinariojoe/panda3d-mapzen
(It is integrating the terrain system with mapzen)