org.opentripplanner.common.geometry.WebMercatorTile Maven / Gradle / Ivy

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The OpenTripPlanner multimodal journey planning system

There is a newer version: 2.6.0

package org.opentripplanner.common.geometry;

import org.geotools.geometry.Envelope2D;
import org.geotools.referencing.crs.DefaultGeographicCRS;

/* http://wiki.openstreetmap.org/wiki/Slippy_map_tilenames */
public class WebMercatorTile {

  public static String getTileNumber(final double lat, final double lon, final int zoom) {
    int xtile = (int) Math.floor((lon + 180) / 360 * (1 << zoom));
    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 ("" + zoom + "/" + xtile + "/" + ytile);
  }

  public static double tile2lon(int x, int z) {
    return x / Math.pow(2.0, z) * 360.0 - 180;
  }

  public static double tile2lat(int y, int z) {
    double n = Math.PI - (2.0 * Math.PI * y) / Math.pow(2.0, z);
    return Math.toDegrees(Math.atan(Math.sinh(n)));
  }

  public static Envelope2D tile2Envelope(final int x, final int y, final int zoom) {
    double maxLat = tile2lat(y, zoom);
    double minLat = tile2lat(y + 1, zoom);
    double minLon = tile2lon(x, zoom);
    double maxLon = tile2lon(x + 1, zoom);
    return new Envelope2D(
      DefaultGeographicCRS.WGS84,
      minLon,
      minLat,
      maxLon - minLon,
      maxLat - minLat
    );
  }
}