将经度和纬度坐标转换为地图像素的图像X和Y坐标Java

Question

我有一张以色列地图。

我需要创建一个获得两个双参数（经度和纬度）的函数，该函数应该在地图图像中的那个区域上画一个小圆圈。

我有以下关于地图的信息：

null

public class MapRenderer extends JFrame {

    public static void main(String... args) throws IOException {

        new MapRenderer();

    }

    public MapRenderer() throws IOException {
        setSize(new Dimension(614, 1141));
        add(new TestPane());
        setVisible(true);
    }

}

class TestPane extends JPanel {

    private BufferedImage image;

    public TestPane() throws IOException {
        File file = new File("israel_map.jpg");
        BufferedImage image = ImageIO.read(file);
        this.image = image;
    }

    @Override
    public void paintComponent(Graphics g) {
        double lon = 34;
        double lat = 33;

        int mapW = 614;
        int mapH = 1141;

        double x = (lon + 180) * (mapW / 360);

        double latRad = lat * Math.PI / 180;

        double mercN = Math.log( Math.tan( (Math.PI  / 4) + (latRad / 2)) );

        double y = (mapH / 2) - (mapW * mercN / (2 * Math.PI));

        System.out.println("[lon: " + lon + " lat: " + lat + "]: X: " + x + " Y: " + y);

        g.drawImage(image, 0, 0, null);
        g.setColor(Color.RED);
        g.drawOval((int) x, (int) y, 5, 5);
    }
}

[lon: 34.0 lat: 33.0]: X: 214.0 Y: 510.3190109117399

截图：

https://gyazo.com/5a19dece37ebace496c6b8d68eb9ec3c

Answer 1

除了像素之外，还需要添加地图的经度/纬度偏移和长度。然后你就可以做一个转换。

static final int mapWidth = 614, mapHeight = 1141;
// offsets
static final double mapLongitudeStart = 33.5, mapLatitudeStart = 33.5;
// length of map in long/lat
static final double mapLongitude = 36.5-mapLongitudeStart, 
        // invert because it decreases as you go down
        mapLatitude = mapLatitudeStart-29.5;

private static Point getPositionOnScreen(double longitude, double latitude){
    // use offsets
    longitude -= mapLongitudeStart;
    // do inverse because the latitude increases as we go up but the y decreases as we go up.
    // if we didn't do the inverse then all the y values would be negative.
    latitude = mapLatitudeStart-latitude;

    // set x & y using conversion
    int x = (int) (mapWidth*(longitude/mapLongitude));
    int y = (int) (mapHeight*(latitude/mapLatitude));

    return new Point(x, y);
}

public static void main(String[] args) {
    System.out.println(getPositionOnScreen(33.5, 33.5).toString());
    System.out.println(getPositionOnScreen(35, 32).toString());
    System.out.println(getPositionOnScreen(36.5, 29.5).toString());
}

这将打印出以下内容：

java.awt.Point[x=0,y=0]
java.awt.Point[x=307,y=427]
java.awt.Point[x=614,y=1141]