The Research Of Three-dimensional Visualization Based On Electronic Navigation Chart

As an important equipment of ship navigation, Two-dimensional electronic navigation chart has a great influence on the automation and intelligence development of maritime.However, the real world is three-dimensional, two-dimensional electronic charts can only use depth and contour to describe the topography of the seabed, there are many problem such as lacking of intuitive expression and completely information, having no benefit for terrain analysis, etc.With the rapid development of Geographic Information System and Computer Graphics,Terrain Visualization is a new technology. The research on Terrain Visualization focuses on land in the present, which means there is little study on seabed topography. Three-dimensional visualization of seabed topography, with flexible operation, intuitive, vivid expression and a very large amount of information, is much more easier to accept, perceive and understand. A Terrain Visualization solution consist of a digital elevation model (DEM), which is constucted based on discretely depth data extracted from two-dimensional electronic chart and realization of terrain three-dimensional modeling is proposed in the paper.Firstly, analysis the data model and package structure of S-57 format electronic chart,write code to extract discrete bathymetric data, and then construct digital elevation model with both traditional interpolation algorithm and fractal interpolation algorithm.Secondly, import the data which has been interpolated and gridded to three-dimensional terrain software MultiGen Creator,select an appropriate method to build terrain model. In order to enhance the readability of the terrain, the terrain needs to add texture. Choose and add texture, comparing the advantages and disadvantages of several terrain textures. With the increasing of terrain area and improvement of texture resolution, the general modeling tool,Creator, can not meet the demand. With the key technologies to solve in large area terrain simulation, use CTS(Creator Terrain Studio) to achieve large area, high-resolution three-dimensional terrain modeling.Thirdly,use Vega Prime, a virtual-reality software,to achieve three-dimensional terrain visualization, and use a variety of enhancement modules (such as Vega Prime Marine, special effects, Path Tool) and other techniques to enhance the rendering power and realism of three-dimensional topographic map. With the introduction of virtual instrument technology,the objects in Vega Prime can interact with virtual instrumentation we designed.Finally,introduce a simple application based on the designed three-dimensional electronic chart. An AHRS display system and Vega Prime program are designed to show inertial information such as attitude and speed, which is provided by MEMS AHRS, in three-dimensional electronic chart.