A new hybrid culling scheme for flight simulator

In flight simulator, real-time rendering system processes most of scenarios at high altitude. Therefore, overload process of real-time rendering system tends to ignore altitude distinction through applying only view-frustum culling. However, even though the flight of the aircraft operates at high altitude, but dynamic culling according to altitude is demanded because of several situations such as takeoff, landing and flight at low altitude. According to this problem statement, in this paper, we propose how to adjust dynamic culling in case of low altitude. To achieve this goal, first, we classify high altitude and low altitude depending on the height of the aircraft motion simulation. Moreover, we apply fuzzy logic into classifies for ambiguous altitude state. If altitude state is low, we use both view-frustum and back-face culling at once in order to reduce complexity of the operations caused by the visibilitytest to dynamically generate the resolution of the ZMap for back-face culling at low altitude state. We use OSG(Open Scene Graph) graphic library and test real world terrain data. Through test results, our proposed algorithm decreases triangles of 15~80% in real-time rending, and improves frame per second of 8~73% as compared to existing one.