Research On Large Scale Circular Ocean Modeling And Rednering

The area of the ocean is approximately 360 million square kilometers, accounting for 71% of the surface area of the earth, is an important part of the natural world. The movement of the ocean is expressed in the way of waves, tides, currents, affecting the climate change, biological distribution, the development of seafaring, which is closely related to human life. In addition, the ocean has abundant mineral resources, biological resources. It also plays an dramatically important role in terms of strengthening national defence and the military deployment, which is a highly concerned strategic field by every country. Therefore, the ocean has wide application in the field of simulation of virtual battlefield, digital earth, marine training, computer game, movie, animation, weather forecast, marine fishery and so on. However, due to the irregularity of the motion of the waves, the large-scale feature of the ocean area, the complexity of the light effect between the ocean and sunshine, sky, it requests high demand to render the ocean in real-time and realistic aspect. Consequently, it is very necessary and challenge to simulate the ocean.In this regard, this thesis sets out from real-time and realistic two aspects, combined with previous research in kinematic oceanography and water simulation, according to the actual project requirements, reorganizes and combines the previous work. Using GPU-based fast fourier transform, viewpoint-based projective grid and other techniques, our system has achieved great effect in both real time and reality. The main research content includes:research on large scale ocean wave modeling technology, research on the light effect of the water body, research on the rendering of the circular ocean grid.The main work of this thesis are as follows:In research of wave modeling technology, we compare several different models, including:physical model based on Navier-Stokes equation, fluid dynamic model based on smooth particles, geometry model based on addition of sine and cosine waves, Gerstner model, perlin noise model, spectrum analysis model based on observation and statistics. In this thesis, in order to achieve better realistic rendering effect and acceptable real time, uses Fast Fourier Transform based on the Phillips spectrum analysis to produce the height of the ocean surface.In research of rendering light effects of the sea water, first introduces the light model of the circular ocean, analyzes the reflection and refraction happened at the ocean surface, and then applies the fresnel law to combine the reflection part and the refraction part. To make up the gap between the color range that computer can render and that of the nature, we employ high dynamic range technique. In order to realize the water color changing with the depth of the water, we render the depth of the ocean to the texture, and then according to the texture values to gradually change the water body’s color. In addition, through the foam texture and caustic texture respectively to achieve the water bubbles and underwater caustics. Finally, we use the godray technique to demonstrate the effect of sunbeam projecting into the water body.In research of rendering of the ocean grid, we first introduce the basic concept of LOD, combined with the previous technique of rendering unlimited flat ocean, compare LOD-based square grid, radioactive circular and elliptic grid. Then we introduce the projection plane division algorithm, coordinates transform and judgment algorithm on ocean visible area so as to only render the part that we can see, to further enhance the real time of ocean rendering.In the end, from the concrete implementation of large-scale circular ocean simulation system, we provide the the problems and deficiencies in this system, and look forward to the development of future technology.