GPS Correction 0.01 Precision Tool / Algorithm Case
Precision tool download: http://map.yanue.net/gps.html
This correction applies to Google map China, Microsoft map china, MapABC, etc., because these maps are the same as the offset.dat file, which is 0.01 precision correction data. If you need it, please contact the website, non-free version.
Algorithm demonstration:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 | <?php /* Code function: Correct the Chinese map latitude and longitude offset with the 0.01 precision correction library file. */ header("Content-Type:text/html; charset=utf-8"); define('__dat_db__' , 'offset.dat' );// DAT the file of data define('datmax' , 9813675 );// Number of data - end record
// # offset.php?lat=39.914914&lon=116.460633 $lon=$_GET['lon']; $lat=$_GET['lat']; $tmplon=intval($lon * 100); $tmplat=intval($lat * 100); //Longitude to pixel X value function lngToPixel($lng,$zoom) { return ($lng+180)*(256<<$zoom)/360; } //Pixel X to longitude function pixelToLng($pixelX,$zoom){ return $pixelX*360/(256<<$zoom)-180; } //Latitude to pixel Y function latToPixel($lat, $zoom) { $siny = sin($lat * pi() / 180); $y=log((1+$siny)/(1-$siny)); return (128<<$zoom)*(1-$y/(2*pi())); } //Pixel Y to latitudefunction pixelToLat($pixelY, $zoom) { $y = 2*pi()*(1-$pixelY /(128 << $zoom)); $z = pow(M_E, $y); $siny = ($z -1)/($z +1); return asin($siny) * 180/pi(); }
function xy_fk( $number ){ $fp = fopen(__dat_db__,"rb"); //■1■.將 r 改為 rb $myxy=$number;//#"112262582"; $left = 0;//Start recording $right = datmax;//end the record
//Use dichotomy to find data while($left <= $right){ $recordCount =(floor(($left+$right)/2))*8; //Take half //echo "Operation：left=".$left." right=".$right." midde=".$recordCount." @fseek ( $fp, $recordCount , SEEK_SET ); //Set cursor $c = fread($fp,8); //Read 8 bytes $lon = unpack('s',substr($c,0,2)); $lat = unpack('s',substr($c,2,2)); $x = unpack('s',substr($c,4,2)); $y = unpack('s',substr($c,6,2)); $jwd=$lon[1].$lat[1]; //echo "Latitude and longitude found:".$jwd; if ($jwd==$myxy){ fclose($fp); return $x[1]."|".$y[1]; break; }else if($jwd<$myxy){ //echo " > ".$myxy." $left=($recordCount/8) +1; }else if($jwd>$myxy){ //echo " < ".$myxy." $right=($recordCount/8) -1; }
} fclose($fp); }
$offset =xy_fk($tmplon.$tmplat); $off=explode('|',$offset); $lngPixel=lngToPixel($lon,18)+$off[0]; $latPixel=latToPixel($lat,18)+$off[1];
echo pixelToLat($latPixel,18).",".pixelToLng($lngPixel,18);
?> |
c#algorithm
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 | using System; using System.Collections.Generic; using System.Linq; using System.Text;
namespace MapDigit.GIS { public class GeoLatLng {
public GeoLatLng(double latitude, double longitude) { this.latitude = latitude; this.longitude = longitude; } public double latitude; public double longitude; }
public class GeoPoint { public GeoPoint(int x, int y) { this.x = x; this.y = y; } public int x; public int y; }
public class OffsetInChina { //Used to convert from GPS coordinates to post-offset coordinates public static GeoLatLng fromEarthToMars(GeoLatLng earth) { GeoPoint ptOffset = getOffset(earth.latitude, earth.longitude); if (ptOffset.x != 0 || ptOffset.y != 0) { int pixelX, pixelY; TileSystem.LatLongToPixelXY(earth.latitude, earth.longitude, 18, out pixelX, out pixelY); GeoPoint pt = new GeoPoint(pixelX, pixelY); pt.x += ptOffset.x; pt.y += ptOffset.y; double latitude, longitude; TileSystem.PixelXYToLatLong(pt.x, pt.y, 18, out latitude, out longitude); return new GeoLatLng(latitude, longitude);
} else { return new GeoLatLng(earth.latitude, earth.longitude); }
}
//Used to convert the post-offset coordinates to true coordinates public static GeoLatLng fromMarToEarth(GeoLatLng mars) { GeoPoint ptOffset = getOffset(mars.latitude, mars.longitude); if (ptOffset.x != 0 || ptOffset.y != 0) { int pixelX, pixelY; TileSystem.LatLongToPixelXY(mars.latitude, mars.longitude, 18, out pixelX, out pixelY); GeoPoint pt = new GeoPoint(pixelX, pixelY); pt.x -= ptOffset.x; pt.y -= ptOffset.y; double latitude, longitude; TileSystem.PixelXYToLatLong(pt.x, pt.y, 18, out latitude, out longitude); return new GeoLatLng(latitude, longitude);
} else { return new GeoLatLng(mars.latitude, mars.longitude); } }
//This function is used to convert the latitude and longitude that needs to be queried into the nearest 0.01 division value, without interpolation. //You can also implement interpolation by yourself. private static GeoPoint getQueryLocation(double latitude, double longitude) { int lat = (int)(latitude * 100); int lng = (int)(longitude * 100); double lat1 = ((int)(latitude * 1000 + 0.499999)) / 10.0; double lng1 = ((int)(longitude * 1000 + 0.499999)) / 10.0; for (double x = longitude; x < longitude + 1; x += 0.5) { for (double y = latitude; x < latitude + 1; y += 0.5) { if (x <= lng1 && lng1 < (x + 0.5) && lat1 >= y && lat1 < (y + 0.5)) { return new GeoPoint((int)(x + 0.5), (int)(y + 0.5)); } } } return new GeoPoint(lng, lat); }
private static GeoPoint getOffset(double longitude, double latitude) { //This function is used to return the result of the query, which is to return the level 18, x, y offset from the corrected data. //Can be implemented by itself return null; }
} } |
