JTS（Geometry）表示圆形_jts polygon

作者：人工智能uu | 2024-08-07 05:18:52

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jts polygon

在平时工作中会涉及一些空间范围的操作，比如两个面求交集，求一个多边形的面积等等，一般都会用到JTS。JTS支持点线面的很多操作，关键字为point、linestring、polygon。

JTS没有直接表示圆的关键字，一般用一个多边形表示圆：

1，确定边数

2，画一个环线

3，根据环线生成面


public class JtsTest {
 
	private static GeometryFactory geometryFactory = new GeometryFactory();
 
	public static Polygon createCircle(double x, double y, final double RADIUS) {
		final int SIDES = 32; // 确定边数
		Coordinate coords[] = new Coordinate[SIDES + 1];
		for (int i = 0; i < SIDES; i++) {
			double angle = ((double) i / (double) SIDES) * Math.PI * 2.0;
			double dx = Math.cos(angle) * RADIUS;
			double dy = Math.sin(angle) * RADIUS;
			coords[i] = new Coordinate((double) x + dx, (double) y + dy);
		}
		coords[SIDES] = coords[0];
		LinearRing ring = geometryFactory.createLinearRing(coords); // 画一个环线
		Polygon polygon = geometryFactory.createPolygon(ring, null); // 生成一个面
		return polygon;
	}
 
	public static void main(String[] args) throws ParseException {
		Polygon p = createCircle(116.45224995263672, 39.988073630126955, 1);
		System.out.println(p);
 
	}
}

接下来用openlayers看一下生成的polygon长什么样子。


<!DOCTYPE html>
<html>
  <head>
    <title>WKT</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v4.6.5/css/ol.css" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
   <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <script src="https://openlayers.org/en/v4.6.5/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      var raster = new ol.layer.Tile({
        source: new ol.source.OSM()
      });
 
 
      var wkt = '';// 把上面生成的polygon复制到这里
      var format = new ol.format.WKT();
 
      var feature = format.readFeature(wkt, {
        dataProjection: 'EPSG:4326'
      });
 
      var vector = new ol.layer.Vector({
        source: new ol.source.Vector({
          features: [feature]
        })
      });
 
      var map = new ol.Map({
        layers: [raster, vector],
        target: 'map',
        view: new ol.View({
          center: [108.560121,36.364153],
		  projection: 'EPSG:4326',
          zoom: 4
        })
      });
    </script>
  </body>
</html>

结果如下图：

说明：

1，第一段代码来自网络其他博客，出处忘记记录，抱歉。

2，第二段代码来自openlayers官网示例，出处：http://openlayers.org/en/latest/examples/wkt.html?q=wkt

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