Design And Application Of Isoline Spatial Analysis System Based On Delaunay Triangulation Network

In the visualization analysis of fishery resources,CPUE(Catch Per Unit Effort)is usually represented by point radius,which lacks correlation between data and is difficult to distinguish the details with naked eyes when there is a large amount of data.When visual superposition analysis is performed with raster data of other factors,the relationship between them can only be obtained by visual qualitative observation because data operation is not involved,which is easy to produce human error.From the perspective of GIS,CPUE is the non-spatial attribute value of fishery point data.It is of great significance to improve data visualization,realize polygon spatial analysis and multidimensional operation to build contour model of non-spatial attribute value of point entity and obtain plane shape range.Therefore,starting from the CPUE data expression,this paper focuses on the two-dimensional visualization and analysis of non-spatial attribute values of point data.Based on the spatial distribution characteristics of CPUE,this paper focuses on two-dimensional visualization and analysis of non-spatial attribute values of point data.According to the characteristics of random point group distribution of fishery data,a general scheme of constructing isoline polygons and conducting polygon superposition analysis based on Delaunay triangular network was proposed.Using Visual Studio 2017 development environment and Arc GIS Engine secondary development component,the isoline spatial analysis system based on Delaunay triangulation network is designed and developed,including data management,isoline polygon construction,spatial overlay analysis,layer display management four functional modules.(1)Data management:Read Excel table data to realize data loading and display,including fishery site data and electronic chart,etc.You can also save,scale,move,globalize,select,and query data from property sheets.(2)Contour polygon construction: Delaunay triangulation network of point data was constructed.Contour lines were tracked according to contour distance to generate contour boundaries.Contour polygon surface data were generated after topology reconstruction.(3)Spatial superposition analysis: perform spatial superposition analysis on isoline polygons of different factors,visualize the superposition result area,and output the data result attribute table.(4)Layer display management: results display and query,layer color setting for isoline polygons,layer removal,addition,movement and editing.Taking the fishery data of Autumn saury in The Northwest Pacific Ocean in October 2019 as an application case,the system functions were tested and verified,and the distribution of fishery resources of Autumn saury in October 2019 was analyzed.The main research contents are as follows:(1)The contour map and contour polygons of CPUE,sea surface temperature(SST)and sea surface height(SSH)of Autumn saberfish in The northwest Pacific Ocean in October 2019 were automatically constructed.The results show that the system can quickly complete the visual expression of point data attribute values in two-dimensional plane.Improve data visualization;(2)the CPUE SST of the high seas and ocean environment factors and the SSH contour polygon in vector spatial overlay analysis of polygon,the results show that the system is preliminary realized the digital output vector polygon overlay analysis,can effectively reduce the observation error,accelerate the process of data analysis,provide convenience for the fishery resources visualization analysis.