Quality Evaluation And Data Representation Of Lunar Discrete Grid Model Based On Regular Icosahedron

With the deepening of lunar exploration around the world,various precision instruments and equipment carried by lunar exploration satellites have collected massive,high-resolution remote sensing images of multiple scales and types,digital elevation models,and other lunar spatial data.How to better organize,manage,express,and utilize these massive amounts of data is a widespread concern among scholars.Currently,the global discrete grid model is considered to be one of the effective solutions to this problem.By dispersing the lunar surface into grids,it can more accurately describe the characteristics of the lunar surface,and facilitate data processing and analysis.In the global discrete grid model system,the spherical discrete grid generation method based on regular polyhedron is a hot research topic.The basic subdivision shapes of regular polyhedrons include triangles,quadrangles,and hexagons.Using different apertures for the same subdivision method will produce completely different discrete grid models.This requires evaluating the quality of discrete grid models to determine their reliability and applicability.The evaluation criteria for grid models are generally based on the classic Goodchild criterion.At the same time,the organization and storage methods of lunar spatial data are generally divided into raster data and vector data.Visualization of these two forms of data grids is a key step in representing spatial data in a discrete grid model.In view of the lack of research on the representation of lunar surface spatial data in spherical discrete grid models,this article has conducted in-depth research on the icosahedral spherical discrete grid model,and the main work carried out is as follows:(1)Aiming at the construction of the lunar discrete grid model,a comprehensive analysis is made of the construction principles of the spherical discrete grid model based on the regular icosahedron.Firstly,the regular icosahedron is positioned and oriented relative to the moon,using the midpoint of one side of the regular icosahedron to pass through the north and south poles of the moon,and making it symmetrical about the moon’s equator to determine;Secondly,determine the combination of the shape and aperture of the regular icosahedral foundation,including hexagonal grids with an aperture of 3,triangular and quadrilateral grids with an aperture of 4,and hexagonal type I and type II grids with an aperture of 4;Finally,Schneider isoproduct projection is used to complete the projection conversion between spherical and planar surfaces,and the construction of five types of regular icosahedral lunar discrete grid models is completed.(2)To evaluate the quality of several lunar discrete grid models constructed based on regular icosahedron,based on the classic Goodchild criterion and referring to different scholars’ evaluation criteria for ideal grid models,five evaluation indicators were selected,namely,cell number,cell area,cell isosphere crown diameter,and cell circumference mean square deviation and area mean square deviation.Using the same dissection method,different basic dissection shapes and apertures were compared,Evaluate the segmentation efficiency,cell geometry,and size uniformity of several combined lunar discrete grid models.Based on the analysis of experimental results,it is concluded that the lunar discrete grid model with a regular icosahedral triangular aperture of 4 is optimal when only considering the efficiency of the mesh division.When comprehensively considering the mesh division efficiency,cell adjacency consistency,angular resolution,and spatial coverage,the type I discrete grid model with a regular icosahedral hexagonal aperture of 4 is optimal,The discrete grid model based on a regular icosahedral hexagon with an aperture of 3 is the worst.(3)Summarize the gridding methods of spherical discrete grid for grid and vector data.For grid data,the gridding method based on pixel center is adopted,and the lunar grid data is gridded and integrated based on the regular icosahedral lunar hexagon discrete grid model,achieving the discrete gridding of global and local morphological images.With the increase of the level of division of the discrete grid model,the better the data expression and fitting effect is,Discrete grids at different levels of segmentation can cover data at different resolutions and are positively correlated;For vector data,the method of data spatial connection is used to establish a spatial connection between a discrete grid model and vector data,to achieve discrete gridding of the entire lunar geological boundary and local geological boundary.The higher the division level,the more accurate the grid fits the geological boundary in all directions,verifying the excellent characteristics of the hexagonal grid in terms of angular resolution and spatial coverage.Finally,a discrete grid data visualization system is developed based on the Cesium map engine to achieve unified integration of the segmented grid data and vector data visualization.