depthTestAgainstTerrain
True if primitives such as billboards, polylines, labels, etc. should be depth-tested against the terrain surface, or false if such primitives should always be drawn on top of terrain unless they're on the opposite side of the globe. The disadvantage of depth testing primitives against terrain is that slight numerical noise or terrain level-of-detail switched can sometimes make a primitive that should be on the surface disappear underneath it.