The vertical coordinates of mesh nodes which are located in the dynamic area can be calculated by formula (6). If the nodes are located in the static area, for the reason of getting high speed calculation, let the vertical coordinates of these nodes equal to tide height.

　

 Because the mesh moves with ownship, it is not necessary to simulate a very large range of sea for real-time simulation. In marine simulator, an area with 6000X6000 m² chosen and the dynamic area is 600X600 m² with 20 meters interval. The interval can also be adjusted according to the hardware performance of image generating system to satisfy the requirement of real-time.

　

　

(2) Texture mapping technology

　

 In visual system, it is impossible to simulate each particle of water in the sea surface directly. Until now, any CGI system can not implement this, so texture mapping technology is adopted mostly in real-time system. An image of certain sea condition is used as texture source and mapped to each mesh to improve the fidelity and speed of simulation. Fig. 5 shows the simulated wave scale No.8 with different wave spectrum.