A Key Technology Research On Patch Of Linear-Object In The Third National Land Survey

The third national land survey is a major survey of national conditions and national strength.It is necessary for social and economic development and land and resources management to master the real data of land use status.On October 16~thh 2017,the state council issued the notice on launching the third national land survey and decided to launch the third national land survey from 2017.The third national territorial survey clearly stipulates that linear-object shall be canceled in the form of line elements,and linear-object with a field width of more than 2m,(such as road land,railway land,river water surface,ditches)shall be shown in the form of patches on the survey.Under this background,this paper studies the key technology on patch of linear-object,and proposes the mathematical and geometric algorithm of patch of linear-object from the theoretical and technical level to provide reference basis for the data processing and area statistics of the third national land survey.This paper takes the 2017 Inner Mongolia Land Survey Key Technology Research Pilot Project as the support and uses Helinger County as the research area,the author uses salient-arc algorithm and angular bisectrix method to analyze the patch of linear-object.This study established a single patch of linear-object and a number of patch of liner-object.Based on the requirements of the third national land survey for linear-object and the actual situation of the research area,the author uses the mathematical geometry method to calculate the area loss value at the corner and vertex overlap of linear-object.In order to ensure the scientificity of the research results,this paper makes use of the virtual model of the linear-object and analyzes the influence factors of linear-object after patch.The following conclusions are obtained by studying the key technology on patch of linear-object:(1)For the single linear-object,the author uses salient-arc algorithm to achieve the area-free loss buffer patch when the corner is equal to pi.In other cases,there will be corner area loss in the buffer patch.The author uses the angular bisectrix method to achieve patch of a single linear-object and no loss of area at the corner,but when the corner is very small,it can not guarantee the equal width of the buffer line.(2)For a plurality of linear-object buffer patch,it can be decomposed into a plurality of single linear-object buffer patch.The author uses salient-arc algorithm to buffer only when a plurality of linear-object shares a vertice,and two linear-objects are collinear to ensure that these two linear-objects have no corners or overlaps.In other cases,there will be area loss in the buffer patch.The author uses angular bisectrix method to buffer the image spotting,so any area loss buffer patch can be realized.Moreover,the method can also verify the accuracy of the area of patch of linear-object in the national land survey database.However,when the corner is very small,the buffer line width cannot be guaranteed.(3)The verification results are consistent with the theoretical research results by verifying the example of patch linear-object.The author uses salient-arc algorithm of ARCGIS software platform to buffer zone of patch of linear-object in the study area.The relative error of the area(?_S(?_S=(S_?S_?)/S_?*100%))after the patch is smaller than that of the MAPGIS software platform.The results of this study can provide a reference for the statistics of patch of liner-object of the third national land survey in the study area.The results of this study can provide a reference for the third national land survey of patch of linear-object.