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] view plain copy

<?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。

[javascript] view plain copy

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/