百度地图根据经纬度计算瓦片行列号
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百度地图根据经纬度计算瓦片行列号
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根據(jù)百度經(jīng)緯度坐標計算該點所在瓦片的行列號的算法好像并沒有公開,網(wǎng)上相關(guān)資料很少。
通過研究百度地圖JavaScript API源代碼(經(jīng)過混淆后的),大致了解計算過程,現(xiàn)將具體過程解釋如下:
1.JavaScript API經(jīng)過混淆后的代碼中包含以下三個方法:
convertMC2LL: function (cC) {var cD, cF;cD = new b4(Math.abs(cC.lng), Math.abs(cC.lat));for (var cE = 0; cE < this.MCBAND.length; cE++) {if (cD.lat >= this.MCBAND[cE]) {cF = this.MC2LL[cE];break}}var T = this.convertor(cC, cF);var cC = new b4(T.lng.toFixed(6), T.lat.toFixed(6));return cC}convertLL2MC: function (T) {var cC, cE;T.lng = this.getLoop(T.lng, -180, 180);T.lat = this.getRange(T.lat, -74, 74);cC = new b4(T.lng, T.lat);for (var cD = 0; cD < this.LLBAND.length; cD++) {if (cC.lat >= this.LLBAND[cD]) {cE = this.LL2MC[cD];break}}if (!cE) {for (var cD = this.LLBAND.length - 1; cD >= 0; cD--) {if (cC.lat <= -this.LLBAND[cD]) {cE = this.LL2MC[cD];break}}}var cF = this.convertor(T, cE);var T = new b4(cF.lng.toFixed(2), cF.lat.toFixed(2));return T}convertor: function (cD, cE) {if (!cD || !cE) {return}var T = cE[0] + cE[1] * Math.abs(cD.lng);var cC = Math.abs(cD.lat) / cE[9];var cF = cE[2] + cE[3] * cC + cE[4] * cC * cC + cE[5] * cC * cC * cC + cE[6] * cC * cC * cC * cC + cE[7] * cC * cC * cC * cC * cC + cE[8] * cC * cC * cC * cC * cC * cC;T *= (cD.lng < 0 ? -1 : 1);cF *= (cD.lat < 0 ? -1 : 1);return new b4(T, cF)}前兩個方法分別負責(zé)將 墨卡托坐標轉(zhuǎn)換成百度坐標、百度坐標轉(zhuǎn)換成墨卡托坐標。
2.仿照編寫出C#版:
//以下是根據(jù)百度地圖JavaScript API破解得到 百度坐標<->墨卡托坐標 轉(zhuǎn)換算法 private static double[] array1 = { 75, 60, 45, 30, 15, 0 }; private static double[] array3 = { 12890594.86, 8362377.87, 5591021, 3481989.83, 1678043.12, 0 }; private static double[][] array2 = {new double[]{-0.0015702102444, 111320.7020616939, 1704480524535203, -10338987376042340, 26112667856603880, -35149669176653700, 26595700718403920, -10725012454188240, 1800819912950474, 82.5},new double[]{0.0008277824516172526, 111320.7020463578, 647795574.6671607, -4082003173.641316, 10774905663.51142, -15171875531.51559, 12053065338.62167, -5124939663.577472, 913311935.9512032, 67.5},new double[]{0.00337398766765, 111320.7020202162, 4481351.045890365, -23393751.19931662, 79682215.47186455, -115964993.2797253, 97236711.15602145, -43661946.33752821, 8477230.501135234, 52.5},new double[]{0.00220636496208, 111320.7020209128, 51751.86112841131, 3796837.749470245, 992013.7397791013, -1221952.21711287, 1340652.697009075, -620943.6990984312, 144416.9293806241, 37.5},new double[]{-0.0003441963504368392, 111320.7020576856, 278.2353980772752, 2485758.690035394, 6070.750963243378, 54821.18345352118, 9540.606633304236, -2710.55326746645, 1405.483844121726, 22.5},new double[]{-0.0003218135878613132, 111320.7020701615, 0.00369383431289, 823725.6402795718, 0.46104986909093, 2351.343141331292, 1.58060784298199, 8.77738589078284, 0.37238884252424, 7.45}}; private static double[][] array4 = {new double[]{1.410526172116255e-8, 0.00000898305509648872, -1.9939833816331, 200.9824383106796, -187.2403703815547, 91.6087516669843, -23.38765649603339, 2.57121317296198, -0.03801003308653, 17337981.2},new double[]{-7.435856389565537e-9, 0.000008983055097726239, -0.78625201886289, 96.32687599759846, -1.85204757529826, -59.36935905485877, 47.40033549296737, -16.50741931063887, 2.28786674699375, 10260144.86},new double[]{-3.030883460898826e-8, 0.00000898305509983578, 0.30071316287616, 59.74293618442277, 7.357984074871, -25.38371002664745, 13.45380521110908, -3.29883767235584, 0.32710905363475, 6856817.37},new double[]{-1.981981304930552e-8, 0.000008983055099779535, 0.03278182852591, 40.31678527705744, 0.65659298677277, -4.44255534477492, 0.85341911805263, 0.12923347998204, -0.04625736007561, 4482777.06},new double[]{3.09191371068437e-9, 0.000008983055096812155, 0.00006995724062, 23.10934304144901, -0.00023663490511, -0.6321817810242, -0.00663494467273, 0.03430082397953, -0.00466043876332, 2555164.4},new double[]{2.890871144776878e-9, 0.000008983055095805407, -3.068298e-8, 7.47137025468032, -0.00000353937994, -0.02145144861037, -0.00001234426596, 0.00010322952773, -0.00000323890364, 826088.5}}; //百度坐標轉(zhuǎn)墨卡托 private static PointF LatLng2Mercator(LatLngPoint p) {double[] arr = null;double n_lat = p.Lat > 74 ? 74 : p.Lat;n_lat = n_lat < -74 ? -74 : n_lat;for (var i = 0; i < array1.Length; i++) {if (p.Lat >= array1[i]) {arr = array2[i];break;}}if (arr == null){for (var i = array1.Length - 1; i >= 0; i--)
{if (p.Lat <= -array1[i]) {arr = array2[i];break;}}}double[] res = Convertor(p.Lng, p.Lat, arr);return new PointF((float)res[0], (float)res[1]); }
//墨卡托坐標轉(zhuǎn)百度 private static LatLngPoint Mercator2LatLng(PointF p) {double[] arr = null;PointF np = new PointF(Math.Abs(p.X),Math.Abs(p.Y));for (var i = 0; i < array3.Length; i++)
{if (np.Y >= array3[i]) {arr = array4[i];break;}}double[] res = Convertor(np.X, np.Y, arr);return new LatLngPoint(res[0],res[1]); } private static double[] Convertor(double x, double y, double[] param) {var T = param[0] + param[1] * Math.Abs(x);var cC = Math.Abs(y) / param[9];var cF = param[2] + param[3] * cC + param[4] * cC * cC + param[5] * cC * cC * cC + param[6] * cC * cC * cC * cC + param[7] * cC * cC * cC * cC * cC + param[8] * cC * cC * cC * cC * cC * cC;T *= (x < 0 ? -1 : 1);cF *= (y < 0 ? -1 : 1);return new double[] { T, cF }; }
3.根據(jù)百度經(jīng)緯度計算出來墨卡托坐標后,將結(jié)果除以地圖分辨率Math.Pow(2,18-zoom)即可得到平面像素坐標,然后將像素坐標除以256分別得到瓦片的行列號。
經(jīng)測試,誤差為0。
作者:周見智?
出處:http://www.cnblogs.com/xiaozhi_5638/?
本文版權(quán)歸作者和博客園共有,歡迎轉(zhuǎn)載,但未經(jīng)作者同意必須保留此段聲明,且在文章頁面明顯位置給出原文連接,否則保留追究法律責(zé)任的權(quán)利。
本文轉(zhuǎn)自周見智博客博客園博客,原文鏈接:http://www.cnblogs.com/xiaozhi_5638/p/4748186.html,如需轉(zhuǎn)載請自行聯(lián)系原作者
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