对于地图坐标偏移，以leaflet为例，有如下解决办法
方法1、修改leaflet源码，解决地图坐标偏移问题
方法2、将点位真实的经纬度经过偏移算法，添加到加密的地图上
方法3、直接对离线地图瓦片进行纠偏
方法1需要修改源码
方法2有缺陷，地图依然是偏移的，如果把地图经纬度显示出来，经纬度也是不对的
我使用的是方法3，原理是：虽然偏移不是线性的，我也不知道纠偏算法，但是在市级或者县级区域，偏移近似线性的，所以对于市级或县级地图应用，可以对地图瓦片进行简单的纠编，优点是得到的地图瓦片可以认为是没有偏移的。
我用C#写了一个高德地图瓦片纠偏程序，代码如下：
1、配置文件
xml version="1.0" encoding="utf-8" ?>
<configuration>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
startup>
<appSettings>
<add key="inputPath" value="D:\_临时文件\GISMap\1818940751"/>
<add key="outputPath" value="D:\_临时文件\GISMapOutput\1818940751"/>
<add key="deltaPixcelX" value="1031"/>
<add key="deltaPixcelY" value="421"/>
<add key="fromMapZoom" value="1"/>
<add key="toMapZoom" value="16"/>
appSettings>
configuration>
deltaPixcelX和deltaPixcelY根据不同城市而不同，单位是像素，在太乐地图下载器上，开启网络，放大到18级，使用下载器的纠偏计算，定位点位和纠偏后的点位，基本用眼可以看出来，差一个格就是256像素，不足一格的自己算一下，就把deltaPixcelX和deltaPixcelY参数算出来了。
2、纠偏代码
using System; using System.Collections.Generic; using System.ComponentModel; using System.Configuration; using System.Data; using System.Drawing; using System.Drawing.Imaging; using System.IO; using System.Linq; using System.Text; using System.Text.RegularExpressions; using System.Threading; using System.Threading.Tasks; using System.Windows.Forms; using Utils; namespace TileProcess { public partial class Form1 : Form { private int _count = 0; private int _deltaPixcelX; private int _deltaPixcelY; private string _inputPath; private string _outputPath; private int _fromMapZoom; private int _toMapZoom; private DateTime _startTime; private int _lastCount; private object _lock = new object(); public Form1() { InitializeComponent(); _deltaPixcelX = Convert.ToInt32(ConfigurationManager.AppSettings["deltaPixcelX"]); _deltaPixcelY = Convert.ToInt32(ConfigurationManager.AppSettings["deltaPixcelY"]); _inputPath = ConfigurationManager.AppSettings["inputPath"]; _outputPath = ConfigurationManager.AppSettings["outputPath"]; _fromMapZoom = Convert.ToInt32(ConfigurationManager.AppSettings["fromMapZoom"]); _toMapZoom = Convert.ToInt32(ConfigurationManager.AppSettings["toMapZoom"]); } private void btnTileProcess_Click(object sender, EventArgs e) { this.btnTileProcess.Enabled = false; Task.Factory.StartNew(() => { LogUtil.Log("开始处理"); Process(); }); Thread thread = new Thread(new ThreadStart(() => { int sleepInterval = 1000; while (true) { Thread.Sleep(sleepInterval); this.BeginInvoke(new Action(() => { double totalSeconds = DateTime.Now.Subtract(_startTime).TotalSeconds; int avg = (int)(_count / totalSeconds); lblMsg.Text = string.Format("已处理 {0} 张瓦片图", _count); if (_count - _lastCount > 0) { lblSpeed.Text = string.Format("当前速度：{0} 张/每秒，平均速度：{1} 张/每秒", (_count - _lastCount) * 1000.0 / sleepInterval, avg); } _lastCount = _count; })); } })); thread.IsBackground = true; thread.Start(); } ////// 瓦片纠偏处理 /// private void Process() { _startTime = DateTime.Now; Regex regex = new Regex(@"\\(\d+)\\(\d+).png", RegexOptions.IgnoreCase); for (int i = _fromMapZoom; i <= _toMapZoom; i++) { int deltaPixcelX = (int)Math.Round(_deltaPixcelX / Math.Round(Math.Pow(2, 18 - i))); int deltaPixcelY = (int)Math.Round(_deltaPixcelY / Math.Round(Math.Pow(2, 18 - i))); string[] fileArr = Directory.GetFiles(_inputPath + "\\" + i, "*.*", SearchOption.AllDirectories); foreach (string file in fileArr) { ThreadData data = new ThreadData(); data.File = file; data.I = i; data.DeltaPixcelX = deltaPixcelX; data.DeltaPixcelY = deltaPixcelY; ThreadUtil.Run((obj) => { ThreadData d = obj as ThreadData; Match match = regex.Match(d.File); if (match.Success) { int x = Convert.ToInt32(match.Groups[1].Value); int y = Convert.ToInt32(match.Groups[2].Value); string pathTarget = string.Format(string.Format(@"{0}\{1}\{2}\{3}.png", _outputPath, d.I, x, y)); if (!File.Exists(pathTarget)) { if (!Directory.Exists(Path.GetDirectoryName(pathTarget))) { Directory.CreateDirectory(Path.GetDirectoryName(pathTarget)); } Bitmap bmpNew = new Bitmap(256, 256, System.Drawing.Imaging.PixelFormat.Format32bppArgb); bmpNew.SetResolution(96, 96); Graphics graph = Graphics.FromImage(bmpNew); int deltaX = data.DeltaPixcelX / 256; int deltaY = data.DeltaPixcelY / 256; //临时变量定义 string pathSource = null; FileStream fs = null; byte[] bArr = null; MemoryStream ms = null; Bitmap bmpSource = null; //起始 pathSource = string.Format(@"{0}\{1}\{2}\{3}.png", _inputPath, d.I, x + deltaX, y + deltaY); if (File.Exists(pathSource)) { fs = new FileStream(pathSource, FileMode.Open, FileAccess.Read); bArr = new byte[fs.Length]; int readCount = fs.Read(bArr, 0, bArr.Length); ms = new MemoryStream(bArr, 0, readCount); bmpSource = new Bitmap(ms); bmpSource.SetResolution(96, 96); graph.DrawImage(bmpSource, 0, 0, new RectangleF(data.DeltaPixcelX % 256, data.DeltaPixcelY % 256, 256 - data.DeltaPixcelX % 256, 256 - data.DeltaPixcelY % 256), GraphicsUnit.Pixel); graph.Flush(); fs.Close(); fs = null; ms.Close(); ms = null; bmpSource.Dispose(); bmpSource = null; } //右 pathSource = string.Format(@"{0}\{1}\{2}\{3}.png", _inputPath, d.I, x + deltaX + 1, y + deltaY); if (File.Exists(pathSource) && (data.DeltaPixcelX > 0 || data.DeltaPixcelY > 0)) { fs = new FileStream(pathSource, FileMode.Open, FileAccess.Read); bArr = new byte[fs.Length]; int readCount = fs.Read(bArr, 0, bArr.Length); ms = new MemoryStream(bArr, 0, readCount); bmpSource = new Bitmap(ms); bmpSource.SetResolution(96, 96); graph.DrawImage(bmpSource, 256 - data.DeltaPixcelX % 256, 0, new RectangleF(0, data.DeltaPixcelY % 256, data.DeltaPixcelX % 256, 256 - data.DeltaPixcelY % 256), GraphicsUnit.Pixel); graph.Flush(); fs.Close(); fs = null; ms.Close(); ms = null; bmpSource.Dispose(); bmpSource = null; } //下 pathSource = string.Format(@"{0}\{1}\{2}\{3}.png", _inputPath, d.I, x + deltaX, y + deltaY + 1); if (File.Exists(pathSource) && (data.DeltaPixcelX > 0 || data.DeltaPixcelY > 0)) { fs = new FileStream(pathSource, FileMode.Open, FileAccess.Read); bArr = new byte[fs.Length]; int readCount = fs.Read(bArr, 0, bArr.Length); ms = new MemoryStream(bArr, 0, readCount); bmpSource = new Bitmap(ms); bmpSource.SetResolution(96, 96); graph.DrawImage(bmpSource, 0, 256 - data.DeltaPixcelY % 256, new RectangleF(data.DeltaPixcelX % 256, 0, 256 - data.DeltaPixcelX % 256, data.DeltaPixcelY % 256), GraphicsUnit.Pixel); graph.Flush(); fs.Close(); fs = null; ms.Close(); ms = null; bmpSource.Dispose(); bmpSource = null; } //右下 pathSource = string.Format(@"{0}\{1}\{2}\{3}.png", _inputPath, d.I, x + deltaX + 1, y + deltaY + 1); if (File.Exists(pathSource) && (data.DeltaPixcelX > 0 || data.DeltaPixcelY > 0)) { fs = new FileStream(pathSource, FileMode.Open, FileAccess.Read); bArr = new byte[fs.Length]; int readCount = fs.Read(bArr, 0, bArr.Length); ms = new MemoryStream(bArr, 0, readCount); bmpSource = new Bitmap(ms); bmpSource.SetResolution(96, 96); graph.DrawImage(bmpSource, 256 - data.DeltaPixcelX % 256, 256 - data.DeltaPixcelY % 256, new RectangleF(0, 0, data.DeltaPixcelX % 256, data.DeltaPixcelY % 256), GraphicsUnit.Pixel); graph.Flush(); fs.Close(); fs = null; ms.Close(); ms = null; bmpSource.Dispose(); bmpSource = null; } bmpNew.Save(pathTarget); //bmpNew.Save("d:\\_临时文件\\1234.png"); //测试用 bmpNew.Dispose(); bmpNew = null; graph.Dispose(); graph = null; } //end if (!File.Exists(pathTarget)) lock (_lock) { _count++; } } //end if (match.Success) }, data, (ex) => { this.BeginInvoke(new Action(() => { lblErrorMsg.Text = "出错：" + ex.Message + "\r\n" + ex.StackTrace; LogUtil.LogError(ex, "出错"); })); }); //end ThreadUtil.Run } //end foreach (string file in fileArr) } //end for (int i = _fromMapZoom; i <= _toMapZoom; i++) } } }
辅助类ThreadUtil：
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading; using System.Threading.Tasks; namespace Utils { ////// 线程工具类 /// public class ThreadUtil { /// /// 使用的逻辑处理器数 /// private static int _ProcessorCount; private static Semaphore _semaphore; private static List _TaskList = new List (); private static object _lock = new object(); static ThreadUtil() { _ProcessorCount = Environment.ProcessorCount * 2 / 4; //使用的逻辑处理器数 if (_ProcessorCount < 1) _ProcessorCount = 1; _semaphore = new Semaphore(_ProcessorCount, _ProcessorCount); } public static void Run(Action<object> doWork, object arg, Action errorAction) { Task task = null; task = Task.Factory.StartNew((obj) => { _semaphore.WaitOne(); try { doWork(obj); } catch (Exception ex) { errorAction(ex); } _semaphore.Release(); lock (_lock) { _TaskList.Remove(task); } }, arg); lock (_lock) { _TaskList.Add(task); } } public static void WaitAll() { Task.WaitAll(_TaskList.ToArray()); } } }
辅助类ThreadData：
using System; using System.Collections.Generic; using System.Linq; using System.Text; using System.Threading.Tasks; namespace TileProcess { public class ThreadData { public int I { get; set; } public string File { get; set; } public int DeltaPixcelX { get; set; } public int DeltaPixcelY { get; set; } } }
写日志工具类就不贴了，可以用其它日志工具代替
处理速度大约每称300张瓦片，具体根据电脑性能不同，一个城市的瓦片大约1个小时左右能处理完。
纠偏后的地图做最佳路径分析，显示的路径和道路基本吻合，略有误差。