Key Technology Study On Marine Hydrological Data Visualization

Ocean, containing rich minerals, energy, and fishery resources, is the principle area for national defense construction, economic development and military struggle. It has important economic and military significance, which is accumulated in the process of the ocean exploitation and military preparation. Marine hydrological data, the fundamental part of basic marine information data, is the important reference of studying the marine physical properties and analyzing the changing process and rules of the activities of wind, wave and current. How to effectively organize and manage these data, and then realize multidimensional dynamic visualization, and show the marine information behind the massive data to user intuitively, is an important aspect in marine visualization. This paper makes a research on the key technology in marine hydrological data visualization. The paper divides the data into scalar field data and vector field data, and then studies their visual implementation respectively. Finally, on the basis of the research, the paper constructs a prototype system for hydrological data visualization. The main works and results of this paper are described as follows:Firstly, this paper expounds the practical significance of marine hydrological data visualization, analyzes the research actuality of technology and platform on marine data visualization, and introduces the research contents and organization of this thesis.Secondly, this paper makes a comprehensive analysis on hydrological data from the aspects such as sources, acquisition, characteristics and the military value, introduces the data modeling and storage method based on NetCDF, and analyzes the interpolation and visualization method of hydrological data on the view of visual representation.Thirdly, this paper realizes the hydrological scalar field visualization by spherical volume rendering. It represents an improved Ray Casting algorithm. Considering the non-uniformity in depth direction, it puts forward the organization of volume data based on texture arrays. Then, it achieves the resampling operation on volume data by the use of coordinate transformation, and uses the virtual octree to accelerate rendering. Finally, it proposes the solution on the question of cone cutting in volume rendering process in order to achieve the freedom in observing the volume rendering results.Fourthly, this paper realizes visualization of the transient and dynamic hydrological vector field, using the method based on texture. In the transient vector field visualization, it puts forward the LIC algorithm based on GPU acceleration, in which it uses the adaptive streamline tracking method to improve the visual effect. In time-varying vector field, it proposes the background texture convolution method to improve the image-blurring problems generated in IBFV algorithm, and achieves the dynamic expression of time-varying vector field through the dynamic data schedule strategy. Finally, it puts forward the color mapping of vector magnitude based on histogram equalization, which enhances the visual effect greatly.Fifthly, this paper designs and realizes a prototype system for hydrological data visualization based on pre-existing 3D visualization platform. It provides the function of flexible analysis of the hydrological data query and interactive visualization, which can make support for comprehensive marine management and battlefield auxiliary decision.