Mapbar地图切片的抓取和拼接算法

转自：http://blog.csdn.net/mygisforum/article/details/7022860

1.MapBar 地图瓦片抓取算法

此地图瓦片抓取算法是根据Mapbarapi里的绘图算法写出来的，使用PHP编写，将代码保存为一个PHP文件后，然后使用命令行运行: $ php -f filename.php。

注：cmd>cd "x:\...\php.exe"。

 <?php
 /**
  * 抓取mapbar切片的算法 by CrossYou at 2011/01/22
  *
  * @version 1.0.0
  * @link    http://crossyou.cn/
  */
 $mapbarImgRoot = './mapbar/';

 //每层地图切片的文件夹名称
 $levelFolder = array('W','0','1','2','3','4','5','6','7','8','9','10','11','12','13','16');

 //每层地图切片所跨的经度数
 $cutImgLonRange=array(90,40,20,10,5,2,1,0.5,0.2,0.1,0.05,0.02,0.01,0.005,0.002,0.001);

 //每层地图切片所跨的维度数
 $cutImgLatRange=array(90*0.8,40*0.8,20*0.8,10*0.8,5*0.8,2*0.8,0.8,0.5*0.8,0.2*0.8,0.1*0.8,0.05*0.8,0.02*0.8,0.01*0.8,0.005*0.8,0.002*0.8,0.001*0.8);

 $blockSize=array(10,10,10,10,10,10,10,10,10,10,50,50,50,50,50,50);

 for($zoomLevel=0;$zoomLevel<16;$zoomLevel++){

     $clipXNum=ceil(360/$cutImgLonRange[$zoomLevel]);
     $clipYNum=ceil(90/$cutImgLatRange[$zoomLevel]);

     $clipLonRange = $cutImgLonRange[$zoomLevel];
     $clipLatRange = $cutImgLatRange[$zoomLevel];

     $clipXGap = -180-$clipLonRange/2;

     //从缩放级别5开始，只抓取中国范围内的地图，因为此级别以后的，非国内的都是背景图，抓了无意义。
     if($zoomLevel>3){

         //--------中国范围的地图
         $west = 73;
         $east = 136;
         $north = 54;
         $south = 3;

         $chinaLonRange = 63;//中国经度跨度
         $chinaLatRange = 51;//中国维度跨度

         $chinaClipXNum = ceil($chinaLonRange/$clipLonRange);
         $chinaClipYNum = ceil($chinaLatRange/$clipLatRange);

         for($i=0;$i<$chinaClipXNum;$i++){
             $lon = $west+$clipLonRange*$i;

             for($j=0;$j<$chinaClipYNum;$j++){
                 $lat = $south+$clipLatRange*$j;

                 $clipXNo =  floor($lon/$cutImgLonRange[$zoomLevel]);
                 $clipYNo =  floor($lat/$cutImgLatRange[$zoomLevel]);

                 $clipXNo=($clipXNo)%$clipXNum;
                 if($clipXNo>=$clipXNum/2)$clipXNo-=$clipXNum;
                 if($clipXNo<-$clipXNum/2)$clipXNo+=$clipXNum;

                 echo "\n新的切片... => \n";
                 echo '经纬度：'.$lon.' , '.$lat."\n";
                 echo "-------------------------------\n";
                 echo '切片序号：'.$clipXNo.' , '.$clipYNo."\n";
                 echo "-------------------------------\n";

                 //切片分文件夹存放位置
                 $folderXNo = (int)floor($clipXNo/$blockSize[$zoomLevel]);
                 //切片分文件夹存放位置
                 $folderYNo = (int)floor($clipYNo/$blockSize[$zoomLevel]);

                 if($folderXNo<0){
                     $folderXNo+=1;
                 }

                 if($folderYNo<0){
                     $folderYNo+=1;
                 }

                 $fileXNo =($clipXNo)-$folderXNo*$blockSize[$zoomLevel];
                 $fileYNo =($clipYNo)-$folderYNo*$blockSize[$zoomLevel];

                 $imgPre = 'http://img.mapbar.com/maplite/mapbank/mapbar/';

                 $imgDir = $levelFolder[$zoomLevel].'/'.$folderXNo.'_'.$folderYNo.'/';
                 $imgName = $fileXNo.'_'.$fileYNo.'.png';
                 $imgUrl = $imgPre.$imgDir.$imgName;
                 $localImgDir = $mapbarImgRoot.$imgDir;

                 $localImgName = $localImgDir.$imgName;
                 if (!is_file($localImgName)){
                     createdir($localImgDir);
                     if(copy($imgUrl,$localImgName)){
                         echo '图片:=> '.$imgDir.$imgName." 成功下载到本地\n\n";
                     }
                 }
             }
         }
     }else{
         for($i= -$clipXNum/2;$i<=$clipXNum/2;$i++){
             $lon = $clipLonRange*$i;
             if($i<0)$lon+=$clipLonRange/2;
             if($i==0)continue;
             if($i>0)$lon-=$clipLonRange/2;

             for($j=-$clipYNum;$j<=$clipYNum;$j++){

                 $lat = $clipLatRange*$j;

                 if($j<0)$lat+=$clipLatRange/2;
                 if($j==0)continue;
                 if($j>0)$lat-=$clipLatRange/2;

                 $clipXNo =  floor($lon/$cutImgLonRange[$zoomLevel]);
                 $clipYNo =  floor($lat/$cutImgLatRange[$zoomLevel]);

                 $clipXNo=($clipXNo)%$clipXNum;
                 if($clipXNo>=$clipXNum/2)$clipXNo-=$clipXNum;
                 if($clipXNo<-$clipXNum/2)$clipXNo+=$clipXNum;

                 echo "\n新的切片... => \n";
                 echo '经纬度：'.$lon.' , '.$lat."\n";
                 echo "-------------------------------\n";
                 echo '切片序号：'.$clipXNo.' , '.$clipYNo."\n";
                 echo "-------------------------------\n";

                 //切片分文件夹存放位置
                 $folderXNo = (int)floor($clipXNo/$blockSize[$zoomLevel]);
                 //切片分文件夹存放位置
                 $folderYNo = (int)floor($clipYNo/$blockSize[$zoomLevel]);

                 if($folderXNo<0){
                     $folderXNo+=1;
                 }

                 if($folderYNo<0){
                     $folderYNo+=1;
                 }

                 $fileXNo =($clipXNo)-$folderXNo*$blockSize[$zoomLevel];
                 $fileYNo =($clipYNo)-$folderYNo*$blockSize[$zoomLevel];

                 $imgPre = 'http://img.mapbar.com/maplite/mapbank/mapbar/';

                 $imgDir = $levelFolder[$zoomLevel].'/'.$folderXNo.'_'.$folderYNo.'/';
                 $imgName = $fileXNo.'_'.$fileYNo.'.png';
                 $imgUrl = $imgPre.$imgDir.$imgName;
                 $localImgDir = $mapbarImgRoot.$imgDir;

                 $localImgName = $localImgDir.$imgName;
                 if (!is_file($localImgName)){
                     createdir($localImgDir);
                     if(copy($imgUrl,$localImgName)){
                         echo '图片:=> '.$imgDir.$imgName." 成功下载到本地\n\n";
                     }
                 }

             }
         }
     }
 }

 /**
  * 创建多级目录 摘自网络
  * 如有好的建议，请到 http://crossyou.cn/给我留言 谢谢！
  *
  * @since 1.0.5
  * @param string $dir
  */
 function createdir($dir){

     $array_dir=explode("/",$dir);//把多级目录分别放到数组中

     $depth = count($array_dir);
     $path = '';
     for($i=0;$i<$depth;$i++){

         $path .= $array_dir[$i]."/";

         if(!is_dir($path)){
             mkdir($path);
         }
     }
 }
 ?>

2.MapBar地图瓦片拼接算法

作者制作的一个Demo：http://www.crossyou.cn/attachments/2011/03/mapbar.html。下面的源代码可能用到了一小点的jQuery。

 var divId = 'map';
 var imgWidth        = 300;
 var imgHeight       = 300;
 var imgExt          = 'png';
 var centerpoint     = '120.15689,35.96333';
 var point           = centerpoint.split(',');
 var _centerLon      = point[0];
 var _centerLat      = point[1];
 var zoomlevel       = 8;
 var $map            = $('#'+divId);

 //每层地图切片的文件夹名称
 var levelFolder     = new Array('W','0','1','2','3','4','5','6','7','8','9','10','11','12','13','16');
 //每层地图切片所跨的经度数
 var cutImgLonRange  = new Array(90,40,20,10,5,2,1,0.5,0.2,0.1,0.05,0.02,0.01,0.005,0.002,0.001);
 //每层地图切片所跨的维度数
 var cutImgLatRange  = new Array(90*0.8,40*0.8,20*0.8,10*0.8,5*0.8,2*0.8,0.8,0.5*0.8,0.2*0.8,0.1*0.8,0.05*0.8,0.02*0.8,0.01*0.8,0.005*0.8,0.002*0.8,0.001*0.8);
 //地图区块大小 将不同区块的放在不同的文件夹下面进行管理
 var blockSize       = new Array(10,10,10,10,10,10,10,10,10,10,50,50,50,50,50,50);

 //纬度的偏移
 var latOffset       = new Array(0,0,0,0,0,0,0,0,75,0,0,-150,0,0,0,0);

 function drawMap(){
     var LatLon          = coordOffsetDecrypt(_centerLon,_centerLat);//解密Mapbar坐标
     centerLon           = LatLon[0];
     centerLat           = LatLon[1];

     var mapwidth        = $map.width();
     var mapheight       = $map.height();

     var halfNum5clipX   = Math.ceil(mapwidth/imgWidth/2);
     var halfNum5clipY   = Math.ceil(mapheight/imgHeight/2);

     var _blockSize      = blockSize[zoomlevel];
     var clipLonRange    = cutImgLonRange[zoomlevel];
     var clipLatRange    = cutImgLatRange[zoomlevel];
     var multiple        = 100000;

     var clipXNum=(360/clipLonRange);
     rotationCosVal=1.0;
     rotationSinVal=0.0;

     var Clip = [];
     clipNo5X=Math.floor((centerLon)/clipLonRange);
     clipNo5Y=Math.floor((centerLat)/clipLatRange);
     if(clipNo5X<0)clipNo5X+=1;

     var mapX=mapwidth/2-Math.round(((centerLon*multiple)%(clipLonRange*multiple))*imgWidth/(clipLonRange*multiple));
     if(centerLat>=0) {
         mapY=mapheight/2-imgHeight+Math.round(((centerLat*multiple)%(clipLatRange*multiple))*imgHeight/(clipLatRange*multiple));
     }else {
         mapY=mapheight/2+Math.round(((centerLat*multiple)%(clipLatRange*multiple))*imgHeight/(clipLatRange*multiple));
     }
     $map.html('');
     // -- 真正给力的开始
     for (var _clipXNo = -halfNum5clipX - 1; _clipXNo <= halfNum5clipX; _clipXNo++) {
         for (var _clipYNo = -halfNum5clipY - 1; _clipYNo <= halfNum5clipY; _clipYNo++) {
             try {
                 var clipXNo = parseInt(clipNo5X + _clipXNo);//地图横向切片序列号
                 var clipYNo = parseInt(clipNo5Y + _clipYNo);
                 clipXNo = (clipXNo) % clipXNum
                 if (clipXNo >= (clipXNum / 2))
                     clipXNo -= clipXNum;
                 if (clipXNo < (-clipXNum / 2))
                     clipXNo += clipXNum;
                 var folderX = parseInt(Math.floor((clipXNo) / _blockSize));
                 var folderY = parseInt(Math.floor((clipYNo) / _blockSize));

                 if (folderX < 0)
                     folderX += 1;
                 if (folderY < 0)
                     folderY += 1;

                 var fileXNo = (clipXNo) - folderX * _blockSize;
                 var fileYNo = (clipYNo) - folderY * _blockSize;

                 var _strImgUrl = 'http://img.mapbar.com/maplite/mapbank/mapbar/' + levelFolder[zoomlevel] + '/';
                 if (zoomlevel >= 14)
                     _strImgUrl += folderX + "/";

                 _strImgUrl += folderX + "_" + folderY + "/";
                 _strImgUrl += fileXNo + "_" + fileYNo + "." + imgExt;

                 var clipLeft = (_clipXNo * imgWidth) + parseInt(mapX);
                 var clipTop = (-(_clipYNo * imgHeight) + parseInt(mapY));

                 clipTop = clipTop + latOffset[zoomlevel];

                 var isClearImgUrl = false;

                 if ((clipLeft < -imgWidth || clipLeft > mapwidth || clipTop > mapheight || clipTop < -imgHeight))
                     isClearImgUrl = true;

                 if (isClearImgUrl)
                     continue;

                 var clipId = ((zoomlevel).toString(16) + (clipNo5X + _clipXNo).toString(16) + 'l' + (clipNo5Y + _clipYNo).toString(16)).toLowerCase();

                 if (_strImgUrl && _strImgUrl.indexOf("NaN") < 0) {
                     if (Clip[clipId] == null) {
                         Clip[clipId] = new Image();
                         Clip[clipId].id = clipId;
                         Clip[clipId].name = clipId;
                         Clip[clipId].unselectable = "on";
                         Clip[clipId].style.position = "absolute";
                         Clip[clipId].style.MozUserSelect = "none";
                         Clip[clipId].src = _strImgUrl;

                     }

                     var p2 = (clipLeft + imgWidth / 2 - mapwidth / 2) * rotationCosVal - (clipTop + imgHeight / 2 - mapheight / 2) * rotationSinVal + mapwidth / 2;
                     var p5 = (clipLeft + imgWidth / 2 - mapwidth / 2) * rotationSinVal + (clipTop + imgHeight / 2 - mapheight / 2) * rotationCosVal + mapheight / 2;

                     Clip[clipId].style.top = parseInt(p5 - imgHeight / 2) + "px";
                     Clip[clipId].style.left = parseInt(p2 - imgWidth / 2) + "px";
                     //var interval = parseInt($('#interval').val());

                     $map.append(Clip[clipId]);
                 }
                 _strImgUrl = null;
             }
             catch (e) {
                 throw (e);
             }
         }
     }
 }

 // The follow is two helper functions

 /**
  * 将真实地理坐标加密为Mapbar经纬度坐标
  *
  * @param x 经度值
  * @param y 维度值
  * @returns [x,y]
  */
 function coordOffsetEncrypt(x,y){
     x = parseFloat(x)*100000%36000000;
     y = parseFloat(y)*100000%36000000;

     _X = parseInt(((Math.cos(y/100000))*(x/18000))+((Math.sin(x/100000))*(y/9000))+x);
     _Y = parseInt(((Math.sin(y/100000))*(x/18000))+((Math.cos(x/100000))*(y/9000))+y);

     return [_X/100000.0,_Y/100000.0];
 }

 /**
  * 将Mapbar经纬坐标解密为真实地理坐标
  *
  * @param x 经度值
  * @param y 维度值
  * @returns [x,y]
  */
 function coordOffsetDecrypt(x,y){
     x = parseFloat(x)*100000%36000000;
     y = parseFloat(y)*100000%36000000;

     x1 = parseInt(-(((Math.cos(y/100000))*(x/18000))+((Math.sin(x/100000))*(y/9000)))+x);
     y1 = parseInt(-(((Math.sin(y/100000))*(x/18000))+((Math.cos(x/100000))*(y/9000)))+y);

     x2 = parseInt(-(((Math.cos(y1/100000))*(x1/18000))+((Math.sin(x1/100000))*(y1/9000)))+x+((x>0)?1:-1));
     y2 = parseInt(-(((Math.sin(y1/100000))*(x1/18000))+((Math.cos(x1/100000))*(y1/9000)))+y+((y>0)?1:-1));

     return [x2/100000.0,y2/100000.0];
 }

 

原文出自 CrossYou'Blog ：

抓取算法：http://www.crossyou.cn/an-algorithm-to-crawl-mapbar-map.htm 

瓦片拼接算法：http://www.crossyou.cn/a-simple-map-of-the-source-code-mapbar.htm

注：以上内容仅供学习，在此严重感谢作者分享。

后记：经验证，百度使用的MapBar的地图，算法相同，其url前缀为：

 http://img.mapbar.com/maplite/mapbank/baidu/