The Application Research Of Marine Simulation And 3D Flow Visualization Based On I4Ocean2.0

Since China launched the strategy of developing the maritime silk road in the 21st century and marine power, the ocean has been an important economic engine for promoting science and technology progress. Ocean is the origin and cradle of life on earth and important for human survival and sustainable development. Facing the fierce competition in the ocean, it becomes an important issue for reasonable exploitation and scientific management of ocean. All the development and management of marine resources, the marine ecological environmental protection, the marine disaster early warning decision, the marine atmospheric environmental research and the marine public service need the support of marine information system. At present, the development of the marine information technology has made obvious progress, but it still face some problems. They mainly exist in the following aspects:Global marine virtual simulation and visualization fundamental platform construction is not mature enough; The method of storage, sharing, processing and analysis for marine big data cannot be effectively applied; The ability of data processing and information mining is weak; The marine data and marine process analysis application and multi-dimensional visualization are not good enough. These defects cause it cannot well meet the needs of the marine scientific research, management and decision making.Around the demands of marine virtual simulation and ocean atmospheric data visualization, this paper designs a virtual reality and visualization platform, called i40cean2.0, which is based on graphical rendering acceleration and hierarchical data scheduling. So the platform could better support the applications of ocean virtual simulation, scientific visualization and synthetical analysis. Taking virtual ocean environment simulation and flow field data visualization as an example, this paper introduces how the i40cean2.0 framework supports the marine applications in detail. Aiming at the space-time characteristics of the marine data, this paper presents a marine spatio-temporal hierarchy model, which can support visual analysis of both three-dimensional(3D) marine scalar field data and vector field data. For better meet the demands for marine operation simulation, marine sports simulation, marine environment simulation, the research work also designs a data structure to load external models. It can be used to support real-time rendering and behavior simulation for static or dynamic models. The geographic information is synchronously rendered in a certain scale at the same time. Visualizing the 3D flow field data dynamically in real time is one of the key problems during the process of marine data analysis and visualization. This paper proposes 3D streamline generating and rendering methods for the regular and irregular flow field data respectively.The innovative work of this paper mainly includes the following contents:(1) The development of virtual reality and visualization platform.An interactive virtual reality and visualization platform is designed. It can not only simulate various elements in marine environment such as water surface, marine effects, marine creatures et al., but also visualize the important information of the invisible features including ocean flow field, sea surface wind field, sea surface temperature and sea surface salinity dynamically. Using the home-developed programmable rendering engine based on GPU to accelerate rendering progress, it manages various visual effects reasonably to help the platform plays a hotter role in the 3D visualization and virtual reality technology in the marine environment analysis and scientific research. Basing on the global marine geographic information system(GIS) framework, this paper sets up a marine information integration, sharing and analysis platform through the spatio-temporal data hierarchy organization and scheduling policy. The platform provides a scientific, effective, convenient and intuitive 3D virtual environment and an analysis tool for marine scientific researchers.(2) The 3D streamline visualization of flow field data.In the marine visualization area,3D dynamic streamline visualization for flow field data is a challenging job. Taking the Princeton Ocean Model (POM) computing data and the Simple Ocean Data Assimilation (SODA) as research objects, this paper separately studies the 3D streamline visualization on the regular and irregular flow field data. For the regular marine data, this paper proposes a solution for the 3D flow visualization challenge based on particle tracking and GPU accelerated streamline generation and rendering algorithm. For the irregular marine data, this paper presents a tetrahedron-based method for generating 3D streamlines. Based on the seeding generating algorithm using the largest connected empty grid and runge-kutta integration algorithm, multi-resolution lines model is achieved to observe different streamline detai Is. To enhance the perception of streamline visualization in virtual environment, animation and opacity strategies are also applied to the streamlines and finally realizes transparent expression of marine spatio-temporal data.(3) Interactive simulation of virtual marine environment.In the simulation of ocean scene, the real-time performance and fidelity are very important factors. This paper seamlessly integrates landscapes with marine scenes and guarantees better rendering efficiency and high quality effects. Combined with the GPU accelerated rendering technology and out-of-core scheduling technology, this paper adopts efficient scenery organization and management strategy to integrate many marine simulation process such as sea surface mesh modeling, sea wave modeling, sea surface optical phenomenon, etc. Both the virtual and visual scene can be interactively controlled based on user preference. The research in this paper can be widely used in many kinds of marine applications.