Observer Mode is a special type of hunting experience developed by DinoHunt Corp.. It allows hunters to learn as much about their targets' behavior as possible. It is also possibly used by harmless tourists visiting the planet on safari.
Observer Mode does have its flaws though. At very, very close range, most herbivores will detect the hunter and flee, while the ceratopsiandinosaurs are able to kill the hunter if he gets too close. In later years, Observer Mode becomes less and less reliable, culminating with all Ice Age animals (excluding the Diatryma) being able to detect the hunter at a very close range and killing him if he gets too close.