GPU-based Real-time Parallel Algorithm For Rendering Underwater Scenes

Modern computer technology has greatly facilitated the development of computergraphics, especially in virtual reality technology, and it is widely applied to variousareas in society, it has directly changed the way people observe and understand theworld. The21st Century is the century of the ocean, and China is a maritime country,the ocean plays an important role in the national economy. Therefore, oceanenvironment simulation becomes very important, which opens yet another window forthe people to understand the ocean.In the past few years, the graphics processing unit (GPU) has been developed ata rapid pace, and has a great potential of replacing the CPU, its scope of application ismore than just graphics rendering, but begin to get involved in the fields of generalpurpose computing. Especially after NVIDIA launched the CUDA parallel computingplatform, the GPU with its ultra-multi-core design, is able to solve complex problemsvery quickly, and has become a shinning star in the field of high performancecomputing. For graphics rendering, due to the complexity of the rendering scene, it ishard to render the scene in real time in the old days. But now we can leave the part ofdata calculation to the GPU, using its powerful parallel computation ability and getresults quickly.This paper is mainly about the realistic rendering of underwater optical effectsincluding underwater god rays, caustics and object shadows. This paper describes aninexpensive yet convincing technique to animate and render underwater god rays inreal-time. It first gives a geometrical model of underwater light shafts, then simulatesthe movement of the water, and finally renders the god ray.Next this paper presents the real physical model for rendering underwater scene,it yields a more realistic effect, but the illumination calculation is verytime-consuming, slows down the overall rendering speed. This paper uses the GPU parallel computing architecture to calculate the light intensity of each vertex, thusgreatly reduces the calculation time of CPU, rapidly improves the rendering speed,and makes the rendering effect more realistic and smooth. Experimental results showthat the proposed method can achieve real-time interactive experience without anysacrifice on image quality.This paper is organized as follows. In first section, the research background ismentioned. Next, the history of GPU computing and CUDA programming model areintroduced. Implementations of underwater god rays and the corresponding parallelalgorithm are elaborated in the next two sections. Then some experiments are doneand analyses of results are reported. Finally, it concludes the paper with some futureworks.The underwater scene rendering can get good results. In future work, the currentflow can be added to simulate and study the marine environment and a seamless wayto explore the land and the ocean is under research. It will take full advantage of GPUfunctionalities to make the underwater optical effects more authentic and natural.