Dart GPS轨迹纠偏算法

功能描述

因项目需求，需要时刻跟踪用户当前位置。定位成功，手机静止不动的情况下，定位也会跳来跳去，总在漂移。

附上Dart代码：

import 'dart:math';
import 'package:amap_all_fluttify/amap_all_fluttify.dart';

/// 

/// 纠偏
/// Rectify deviation
/// GPS纠偏算法，适用于google,高德体系的地图
/// 

class Rectification {
  static const double Pi = 3.14159265358979324;
  static const double A = 6378245.0;
  static const double Ee = 0.00669342162296594323;

  static LatLng transform(double wgLat, double wgLon) {
    if (outOfChina(wgLat, wgLon)) {
      LatLng latlng = LatLng(wgLat, wgLon);
      return latlng;
    }
    double dLat = _transformLat(wgLon - 105.0, wgLat - 35.0);
    double dLon = _transformLon(wgLon - 105.0, wgLat - 35.0);
    double radLat = wgLat / 180.0 * Pi;
    double magic = sin(radLat);
    magic = 1 - Ee * magic * magic;
    double sqrtMagic = sqrt(magic);
    dLat = (dLat * 180.0) / ((A * (1 - Ee)) / (magic * sqrtMagic) * Pi);
    dLon = (dLon * 180.0) / (A / sqrtMagic * cos(radLat) * Pi);

    LatLng latlng = LatLng(wgLat + dLat, wgLon + dLon);
    return latlng;
  }

  static bool outOfChina(double lat, double lon) {
    if (lon < 72.004 || lon > 137.8347) return true;
    if (lat < 0.8293 || lat > 55.8271) return true;
    return false;
  }

  static double _transformLat(double x, double y) {
    double ret = -100.0 +
        2.0 * x +
        3.0 * y +
        0.2 * y * y +
        0.1 * x * y +
        0.2 * sqrt(x.abs());
    ret += (20.0 * sin(6.0 * x * Pi) + 20.0 * sin(2.0 * x * Pi)) * 2.0 / 3.0;
    ret += (20.0 * sin(y * Pi) + 40.0 * sin(y / 3.0 * Pi)) * 2.0 / 3.0;
    ret += (160.0 * sin(y / 12.0 * Pi) + 320 * sin(y * Pi / 30.0)) * 2.0 / 3.0;
    return ret;
  }

  static double _transformLon(double x, double y) {
    double ret =
        300.0 + x + 2.0 * y + 0.1 * x * x + 0.1 * x * y + 0.1 * sqrt(x.abs());
    ret += (20.0 * sin(6.0 * x * Pi) + 20.0 * sin(2.0 * x * Pi)) * 2.0 / 3.0;
    ret += (20.0 * sin(x * Pi) + 40.0 * sin(x / 3.0 * Pi)) * 2.0 / 3.0;
    ret +=
        (150.0 * sin(x / 12.0 * Pi) + 300.0 * sin(x / 30.0 * Pi)) * 2.0 / 3.0;
    return ret;
  }
}

原理我也在研究中，有懂的同学不妨留言。

附上GitHub地址：https://github.com/fluttify-project/amap_map_fluttify/issues/187