OcclusionPrecision

Triangle-accurate, through Ava3DView.Pick — the same test a click uses, so a marker hides exactly when a click at that pixel would hit something nearer. The default.

Bounding boxes only. Cheaper by roughly the cost of the triangle pass, and wrong in one direction: a marker inside another object's box hides while it is still visible through a gap. Worth having when there are many markers, or when the geometry in front is dense and solid anyway.