Question

我正在努力解决问题：我想通过我的Java应用程序访问openstreetmap。我写了一个JComponent，它能够显示从openstreetmap下载的磁贴。问题在于，在计算下载图片的y位置（参见源代码中的FIXME）的公式中，这是一个错误，我无法找到它。代码的某些部分是从http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames复制的。疯狂的是x-position是正确的。 goTo()方法用于确定地图的哪个位置应位于JComponent的中心 - 查看！

package ui;

import java.awt.Graphics;
import java.awt.Image;

import javax.swing.JComponent;

public class OSMViewer extends JComponent {

    private static final long serialVersionUID = 1L;
    protected ImageHandler imagehandler = null;
    protected int zoomlevel = 0;
    protected double center_deg_lon = 0.0;
    protected double center_deg_lat = 0.0;
    final double DEGY = 85.0511;
    final double DEGX = 180.0;

    public OSMViewer(ImageHandler imagehandler) {
        this.imagehandler = imagehandler;
        // TODO
        goTo(13, 30.0, 30.0);
    }

    public void goTo(final int zoom, final double lon, final double lat) {
        zoomlevel = zoom;
        center_deg_lon = lon;
        center_deg_lat = lat;
        repaint();
    }

    // deg
    public int getTileNumberX(final int zoom, final double lon) {
        int xtile = (int) Math.floor((lon + 180) / 360 * (1 << zoom));
        return xtile;
    }

    // deg
    public int getTileNumberY(final int zoom, final double lat) {
        int ytile = (int) Math
                .floor((1 - Math.log(Math.tan(Math.toRadians(lat)) + 1
                        / Math.cos(Math.toRadians(lat)))
                        / Math.PI)
                        / 2 * (1 << zoom));
        return ytile;
    }

    // deg
    public double getLonDegPx(final int zoom) {
        double deg_px = 2 * DEGX / (Math.pow(2, zoom) * 256);
        return deg_px;
    }

    // deg
    public double getLatDegPx(final int zoom) {
        double deg_px = 2 * DEGY / (Math.pow(2, zoom) * 256);
        return deg_px;
    }

    // deg
    public int getPxX(final int zoom, final double lon) {
        return (int) (((lon + DEGX) / (2 * DEGX)) * Math.pow(2, zoom) * 256);
    }

    // deg
    public int getPxY(final int zoom, final double lat) {
        return (int) (((DEGY - lat) / (2.0 * DEGY)) * Math.pow(2.0, zoom) * 256.0);
    }

    public void paintComponent(Graphics g) {
        int x = getTileNumberX(zoomlevel, center_deg_lon);
        int y = getTileNumberY(zoomlevel, center_deg_lat);
        String str = ("" + zoomlevel + "/" + x + "/" + y);
        System.out.println(str);
        int xpos = (x * 256) - getPxX(zoomlevel, center_deg_lon)
                + (getWidth() / 2);
        // FIXME
        int ypos = (y * 256) - getPxY(zoomlevel, center_deg_lat)
                + (getHeight() / 2);
        Image image = imagehandler.getImage(str);
        if (image != null) {
            g.drawImage(image, xpos, ypos, this);
        }
        g.drawLine(0, getHeight() / 2, getWidth(), getHeight() / 2);
        g.drawLine(getWidth() / 2, 0, getWidth() / 2, getHeight());
    }
}

Answer 1

很高兴听到您能够解决您的问题:) 另请注意，OSM在捐赠的资源上运行，并限制人们访问rendererd地图图块的方式：http://wiki.openstreetmap.org/wiki/Tile_usage_policy请注意您的应用尊重它，以避免给社区服务器带来压力。

Openstreetmap Viewer：坐标转换错误

1 个答案: