处理WKT面数据自相交问题

一、引入terraformer

Terraformer 是一个几何工具包，用于处理不同的几何格式和构建地理数据库。
Terraformer 是Esri的一个开源项目，功能如下：

<script src="https://unpkg.com/terraformer@1.0.8"></script>
<script src="https://unpkg.com/terraformer-arcgis-parser@1.0.5"></script>
<script src="https://unpkg.com/terraformer-wkt-parser@1.1.2"></script>

//WKT格式测试数据
var wktData =
      "POLYGON((118.48859787838352 37.466855887587926,118.48377465024234 37.44892970037951,118.50637309434643 37.448117310665495,118.50691167095988 37.448054561187064,118.50671711924377 37.4538244183002,118.50667363936907 37.4572565405026,118.51339469876487 37.45753381461357,118.51330829093396 37.45970018196293,118.50023196806373 37.45963985156324,118.50257883055443 37.47144541012767,118.51207915768441 37.47080863641392,118.51199204477498 37.47906744882793,118.50402135503961 37.47895797487516,118.5030309092051 37.47427843413634,118.50294475156741 37.47414946318135,118.48952348689284 37.47297242899381,118.48861941218955 37.46694175571052,118.48861939994451 37.46702756470185,118.48866249318695 37.46696333780628,118.48859787838352 37.466855887587926))";

二、处理流程

1. WKT数据转GeoJson

var geojson = Terraformer.WKT.parse(wktData);

2. GeoJson数据转ArcGIS数据

var arcgis = Terraformer.ArcGIS.convert(geojson);

3. ArcGIS数据使用ArcGIS API 操作
   （1）使用simplify()将自相交面分成不自相交的多面；
   simplify()对几何图形执行简化操作，该操作会更改给定的几何图形，以使其在拓扑上合法。

var geometry = geometryJsonUtils.fromJson(arcgis);
var geo = geometryEngine.simplify(geometry);

（2）判断每个面的端点个数，点数最多的为结果面，展示到地图上：

var geoRing = null;
        for (let i = 0; i < geo.rings.length; i++) {
          geoRing = geo.rings[0];
          if (geo.rings[i].length > geoRing.length) {
            geoRing = geo.rings[i]
          }
        }
        var polygon = new Polygon([geoRing]);
        var gh = new Graphic(polygon, symbol);
        ghLayer.add(gh)
        map.setExtent(polygon.getExtent().expand(1.5)); //定位并放大1.5倍

（3）或者判断每个面的面积，面积最大的为结果面，展示到地图上：

var geoRing = null;
        var geoAreas = [];
        var area = 0;
        for (let i = 0; i < geo.rings.length; i++) {
          var poly = new Polygon([geo.rings[i]]);
          geoAreas[i] = geometryEngine.geodesicArea(poly, "acres");
          geoRing = geo.rings[0];
          if (area < geoAreas[i]) {
            area = geoAreas[i];
            geoRing = geo.rings[i]
          }
        }
        var polygon = new Polygon([geoRing]);
        var gh = new Graphic(polygon, symbol);
        ghLayer.add(gh)
        map.setExtent(polygon.getExtent().expand(1.5)); //定位并放大1.5倍

4.ArcGIS数据转GeoJson

var geojson2 = Terraformer.ArcGIS.toGeoJSON(polygon);

5.GeoJson数据转WKT

var result = Terraformer.WKT.convert(geojson2);

三、处理结果

1. 处理前：
   

2. 处理后：
   

标签：polygon,geoRing,处理,rings,相交,var,geo,WKT,Terraformer
来源： https://blog.csdn.net/ahappyday222/article/details/115401806