经纬度墨卡托互相转换-WGS84 and Mercator transfer each other

转自barry.z-
http://bbs.esrichina-bj.cn/ESRI/thread-78245-1-1.html


//经纬度转墨卡托
-(CGPoint )lonLat2Mercator:(CGPoint ) lonLat
{
    CGPoint  mercator;
    double x = lonLat.x 20037508.34/180;
    double y = log(tan((90+lonLat.y)M_PI/360))/(M_PI/180);
    y = y 20037508.34/180;
    mercator.x = x;
    mercator.y = y;
    return mercator ;
}
//墨卡托转经纬度
-(CGPoint )Mercator2lonLat:(CGPoint ) mercator
{
    CGPoint lonLat;
    double x = mercator.x/20037508.34180;
    double y = mercator.y/20037508.34180;
    y= 180/M_PI(2atan(exp(yM_PI/180))-M_PI/2);
    lonLat.x = x;
    lonLat.y = y;
    return lonLat;
}