java-如何在geoTools中使用GeometricShapeFactory在地图上创建圆

我目前正在使用以下代码创建GeoJson多边形.这给了我一个不好的圈子,这是无效的…

在这种情况下RADIUS = 1609.34,以米为单位1英里.

        public  GeoJsonPolygon createRadiusPolygon(  Point point,double RADIUS) {       

              GeometricShapeFactory shapeFactory = new GeometricShapeFactory();
              shapeFactory.setNumPoints(32);
              shapeFactory.setCentre(new com.vividsolutions.jts.geom.Coordinate(point.getX(), point.getY()));
              shapeFactory.setSize(RADIUS * 2);
              com.vividsolutions.jts.geom.Geometry circle = shapeFactory.createCircle();
              List<Point> points = new ArrayList<Point>();
                for (com.vividsolutions.jts.geom.Coordinate coordinate : circle.getCoordinates()) {
                    Point lngLatAtl = new Point(coordinate.x, coordinate.y);
                    points.add(lngLatAtl);
                }
                Collections.reverse(points);
                return new GeoJsonPolygon(points);
            }

引用：
http://docs.geotools.org/stable/userguide/library/jts/geometry.html

当前如果我使用Point(-73.87,40.84)RADIUS = 1609.34,我会得到以下链接.
https://gist.githubusercontent.com/VanitySoft/56c4ce0f5c1c7e7fe0461ed46fd5ed11/raw/94544750a140d81780ebe9206395a21ab88bb1f7/circle

===已解决==来自@Ian答案：
在他的答案中使用方法. RADIUS以英里为单位,以获取用于创建GeoJson的Circle.

...
  com.vividsolutions.jts.geom.Point jtsPoint =  new GeometryFactory().createPoint(new com.vividsolutions.jts.geom.Coordinate(point.getY(), point.getX()));
                  javax.measure.Measure measure = Measure.valueOf(RADIUS, NonSI.MILE);
                  com.vividsolutions.jts.geom.Geometry circle = createCircleRadis(measure,CRS.decode("epsg:4326"),jtsPoint );
...

…

最佳答案

您的输出圆是有效的,它恰好超过了地球表面的直径,因此您的GIS可能无法绘制它！问题在于,您是在无差别地混合度和米,而GeoTools不知道您想做什么.

您需要向程序中添加有关该点的坐标参考系的一些信息,如果该投影是地理投影(即度),则将问题转换为以米为单位的投影.

public Geometry bufferPoint(Measure<Double, Length> distance, CoordinateReferenceSystem origCRS, Geometry geom) {
    Geometry pGeom = geom;
    MathTransform toTransform, fromTransform = null;
    // reproject the geometry to a local projection
    Unit<Length> unit = distance.getUnit();
    if (!(origCRS instanceof ProjectedCRS)) {

      double x = geom.getCoordinate().x;
      double y = geom.getCoordinate().y;

      String code = "AUTO:42001," + x + "," + y;
      // System.out.println(code);
      CoordinateReferenceSystem auto;
      try {
        auto = CRS.decode(code);
        toTransform = CRS.findMathTransform(DefaultGeographicCRS.WGS84, auto);
        fromTransform = CRS.findMathTransform(auto, DefaultGeographicCRS.WGS84);
        pGeom = JTS.transform(geom, toTransform);
        unit = SI.METER;
      } catch (MismatchedDimensionException | TransformException | FactoryException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }

    } else {
      unit = (Unit<Length>) origCRS.getCoordinateSystem().getAxis(0).getUnit();

    }


    // buffer
    Geometry out = pGeom.buffer(distance.doubleValue(unit));
    Geometry retGeom = out;
    // reproject the geometry to the original projection
    if (!(origCRS instanceof ProjectedCRS)) {
      try {
        retGeom = JTS.transform(out, fromTransform);

      } catch (MismatchedDimensionException | TransformException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
      }
    }
    return retGeom;
  }

AUTO：42001,x,y是一个特殊的投影,以点x,y为中心,以米为单位,它使我们能够使用JTS buffer方法,该方法比您使用的圆操作更容易.

对于您的输入,这使我对纽约有所了解,请注意,这是预期的,并且是由于在弯曲的地球上使用未投影的纬度/经度坐标造成的失真影响.

您可以使用以下方式调用它：

//Measure<Double, Length> dist = Measure.valueOf(50.0, SI.KILOMETER);
Measure<Double, Length> dist = Measure.valueOf(1.0, NonSI.MILE);
GeometryFactory gf = new GeometryFactory();
Point p = gf.createPoint(new Coordinate(-73.87,40.84));
buf.bufferPoint(dist, DefaultGeographicCRS.WGS84, p);

enter image description here