高德离线地图瓦片坐标偏移纠偏

(地图瓦片纠偏最好的方法在这：https://www.cnblogs.com/s0611163/p/15606460.html)

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" />
  </appSettingsadd key="inputPath" value="D:\_临时文件\GISMap\1818940751"/>
    ="outputPath"="D:\_临时文件\GISMapOutput\1818940751"="deltaPixcelX"="1031"="deltaPixcelY"="421"="fromMapZoom"="1"="toMapZoom"="16">
>

View Code

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;
 System.Collections.Generic;
 System.ComponentModel;
 System.Configuration;
 System.Data;
 System.Drawing;
 System.Drawing.Imaging;
 System.IO;
 System.Linq;
 System.Text;
 System.Text.RegularExpressions;
 System.Threading;
 System.Threading.Tasks;
 System.Windows.Forms;
 Utils;

namespace TileProcess
{
    public partial class Form1 : Form
    {
        private int _count = 0;
        int _deltaPixcelX;
         _deltaPixcelY;
        string _inputPath;
         _outputPath;
         _fromMapZoom;
         _toMapZoom;

        private DateTime _startTime;
         _lastCount;

        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]);
        }

        void btnTileProcess_Click( 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 > )
                        {
                            lblSpeed.Text = 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 = ;
            thread.Start();
        }

        /// <summary>
        /// 瓦片纠偏处理
        </summary>
        void Process()
        {
            _startTime = DateTime.Now;
            Regex regex = new Regex(@"\\(\d+)\\(\d+).pngnoreCase);
            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( i)));

                string[] fileArr = Directory.GetFiles(_inputPath + \\" + i,1)">*.*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({0}\{1}\{2}\{3}.pngif (!File.Exists(pathTarget))
                            {
                                Directory.Exists(Path.GetDirectoryName(pathTarget)))
                                {
                                    Directory.CreateDirectory(Path.GetDirectoryName(pathTarget));
                                }
                                Bitmap bmpNew = new Bitmap(256,1)">256stem.Drawing.Imaging.PixelFormat.Format32bppArgb);
                                bmpNew.SetResolution(96,1)">96);
                                Graphics graph = Graphics.FromImage(bmpNew);

                                int deltaX = data.DeltaPixcelX / ;
                                int deltaY = data.DeltaPixcelY / ;

                                //临时变量定义
                                string pathSource = null;
                                FileStream fs = byte[] bArr = ;
                                MemoryStream ms = ;
                                Bitmap bmpSource = 起始
                                pathSource =  deltaY);
                                 (File.Exists(pathSource))
                                {
                                    fs =  FileStream(pathSource,FileMode.Open,FileAccess.Read);
                                    bArr = byte[fs.Length];
                                    int readCount = fs.Read(bArr,bArr.Length);
                                    ms = new MemoryStream(bArr,readCount);
                                    bmpSource =  Bitmap(ms);
                                    bmpSource.SetResolution();
                                    graph.DrawImage(bmpSource,0,new RectangleF(data.DeltaPixcelX % 256 - data.DeltaPixcelX % 256 - data.DeltaPixcelY % ),GraphicsUnit.Pixel);
                                    graph.Flush();

                                    fs.Close();
                                    fs = ;
                                    ms.Close();
                                    ms = ;
                                    bmpSource.dispose();
                                    bmpSource = ;
                                }

                                右
                                pathSource = 1,1)">if (File.Exists(pathSource) && (data.DeltaPixcelX > 0 || data.DeltaPixcelY > ))
                                {
                                    fs = new RectangleF(下
                                pathSource = );
                                右下
                                pathSource = ;
                                }

                                bmpNew.Save(pathTarget);
                                bmpNew.Save("d:\\_临时文件\\1234.png"); 测试用

                                bmpNew.dispose();
                                bmpNew = ;
                                graph.dispose();
                                graph = ;
                            } end if (!File.Exists(pathTarget))

                            lock (_lock)
                            {
                                _count++;
                            }
                        } end if (match.Success)
                    },data,(ex) =>
                        {
                            lblErrorMsg.Text = 出错：" + ex.Message + \r\n" + ex.StackTrace;
                            LogUtil.LogError(ex,1)">出错);
                        }));
                    }); end ThreadUtil.Run
                } end foreach (string file in fileArr)
            } end for (int i = _fromMapZoom; i <= _toMapZoom; i++)
        }

    }
}

View Code

辅助类ThreadUtil：

 System.Threading.Tasks;

 Utils
{
    <summary>
     线程工具类
    </summary>
     ThreadUtil
    {
         使用的逻辑处理器数
        static  _ProcessorCount;
        static Semaphore _semaphore;
        static List<Task> _TaskList = new List<Task>();
         ThreadUtil()
        {
            _ProcessorCount = Environment.ProcessorCount * 2 / 4; 使用的逻辑处理器数
            if (_ProcessorCount < 1) _ProcessorCount = ;
            _semaphore =  Semaphore(_ProcessorCount,_ProcessorCount);
        }

        void Run(Action<object> doWork,1)">object arg,Action<Exception> errorAction)
        {
            Task task = ;
            task = Task.Factory.StartNew((obj) =>
            {
                _semaphore.WaitOne();

                try
                {
                    doWork(obj);
                }
                catch (Exception ex)
                {
                    errorAction(ex);
                }

                _semaphore.Release();

                 (_lock)
                {
                    _TaskList.Remove(task);
                }
            },arg);

             (_lock)
            {
                _TaskList.Add(task);
            }
        }

         WaitAll()
        {
            Task.WaitAll(_TaskList.ToArray());
        }
    }
}

View Code

辅助类ThreadData：

 ThreadData
    {
        int I { get; set; }
        string File { int DeltaPixcelX { int DeltaPixcelY { ; }
    }
}

View Code

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。

还有另一种纠偏方法，通过修改leaflet源码进行纠偏：https://www.cnblogs.com/s0611163/p/13396622.html

高德离线地图瓦片坐标偏移纠偏

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