The Visualization Method Of Spherical Hexagonal Grid For Local Multi Resolution

Compared to other grid system, the Latitude and longitude grid has characteristics that the adjacent relation is not unique, space area is uneven, etc., which will inevitably result in data redundancy and neighborhood calculation accuracy deficiency while the Latitude and longitude grid is introduced as the underlying structure of global data visualization. In contrast, the hexagonal grid is better with advantages that homogeneous distribution, compact structure and unique adjacent relation. However, its multi-resolution visualization has been the difficulty of the research field. To solve this problem, a new multi-resolution method of hexagonal grid that spherical hexagon grid local multi-resolution visualization was proposed. It combines the characteristics of hexagonal and rhombic mesh, so the hexagonal grid can use quadtree to conduct the level management, some common quadtree algorithm can also be applied on the hexagonal grid.The main work includes the following three aspects. Firstly, a new coding scheme of the hexagonal grid was present; Use the rhombus quadruple to encode the spherical hexagon grid,of which the aperture is 4. And introduce the quadtree to manage the grid level, which greatly improved the grid level management efficiency. The method is simple with clear hierarchy. And compared with the algorithm of Xiaochong Tong et al, the grid level index algorithm is more simple and understandable.Secondly, cracks between hexagonal grid blocks with different levels were solved;Considering that it would inevitably appear cracks between grid blocks with different levels, the triangle strip method was employed to solve the crack problem, which makes the rhombus grid blocks with different levels achieve seamless joint on the sphere.Finally, a complete set of algorithms of spherical hexagon grid real-time LOD was realized; In order to render the spherical hexagon grid with multi-resolution in real time, a view-dependent LOD scheduling algorithm based on the quadtree was designed. The algorithm can update the rendering of the hexagonal grid with proper resolution in realtime and realize the crack mending according to the change of the viewpoint position. The frame rate is at 500 frames per second, which can meet the requirement of real-time rendering.The experimental results show that the multi-resolution visualization method of the spherical hexagon reaches the design requirement in the rendering efficiency and it can also achieve the local multi-resolution visualization, the average frame rate can reach 500 frames per second.