| With the advances of earth observation, data processing and other technology, the digital earth technology has developed very rapidly in recent years and been applied rapidly in various fields, especially in the virtual battlefield and combat simulation. In these fields, it plays important part in the true feeling of system to model and render the ocean surface which covers about 70% of the entire earth surface. In some applications, the ocean surface itself is the emphases of visualization and the basal environment of other applications. This paper aims to render the ocean surface rapidly and realistically based on studying ocean wave model and ocean surface grid generation.The main results and innovation are:1. Improve the ocean wave model based on Perlin noise. The improved model may be applied to render ocean surface on digital earth, which solves many problems such as huge computation quantity and compression phenomenon in the high latitude.2. Propose a viewpoint correlation spherical highly field grid generation algorithm. It adopt Projection Plane Division Algorithm because of the difficulty of computing spherical visible region. According to the point of intersection of the line through viewpoint and projection plane sampling point and earth's surface, it generates the earth's surface visible region multi-resolution grid, then, according to the sea and land judgement algorithm, generates ocean surface visible region multi-resolution grid. This method can generate dynamic spherical surface multi- resolution grid according to the change of viewpoint position and direction, moreover, can transit between the different levels of detail continuously.3. Simulate the ocean surface illumination effect and the sky. It adopts simplified illumination model to simulate the ocean surface illumination effect, and adopts spherical method to sumulate the sky.4. Realize a ocean surface modeling and rendering prototype system which confirms the feasibility and accuracy of the algorithms. |
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