刘航：基于PostGIS的空间数据实时编辑与拓扑检查-企业GIS专场（35页）.pdf

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1、基于PostGIS的空间数据实时编辑与拓扑检查演讲人：刘航CONTENTS 目录01PART ONE 实时编辑实时编辑02PART TWO 空间拓扑空间拓扑03PART THREE 拓展拓展01 数据编辑与问题优化C/S数据编辑用户GIS软件SHP、GDBGeoJSONB/S数据编辑用户浏览器服务端DBDBDBSHP、GDBGeoJSON数据操作ST_SplitThe function supports splitting a line by(multi)point,(multi)line or(multi)polygon boundary,a(multi)polygon by line.Th

2、e returned geometry is always a collection.Think of this function as the opposite of ST_Union.Theoretically applying ST_Union to the elements of the returned collection should always yield the original geometry.切割前切割后ST_UnionOutput type can be a MULTI*,single geometry,or Geometry Collection.Comes in

3、 2 variants.Variant 1 unions 2 geometries resulting in a new geometry with no intersecting regions.Variant 2 is an aggregate function that takes a set of geometries and unions them into a single ST_Geometry resulting in no intersecting regions.合并前合并后成功了？存在问题：切割后合并存在短线问题优化方案：ST_Buffer(geometryg1,floa

4、tradius_of_buffer,textbuffer_style_parameters=)优化方案：ST_Snap(geometryinput,geometryreference,floattolerance)ST_BuffergeometryST_Buffer(geometryg1,floatradius_of_buffer,textbuffer_style_parameters=);geometryST_Buffer(geometryg1,floatradius_of_buffer,integernum_seg_quarter_circle);ST_BuffergeometryST_B

5、uffer(geometryg1,floatradius_of_buffer,textbuffer_style_parameters=);geometryST_Buffer(geometryg1,floatradius_of_buffer,integernum_seg_quarter_circle);ST_SnapgeometryST_Snap(geometryinput,geometryreference,floattolerance);SnapstheverticesandsegmentsofageometrytoanotherGeometrysvertices.Asnapdistance

6、toleranceisusedtocontrolwheresnappingisperformed.Theresultgeometryistheinputgeometrywiththeverticessnapped.Ifnosnappingoccursthentheinputgeometryisreturnedunchanged.Snappingonegeometrytoanothercanimproverobustnessforoverlayoperationsbyeliminatingnearly-coincidentedges(whichcauseproblemsduringnodinga