GeoTools坐標轉換（投影轉換和仿射變換）

GeoTools是在java下的gis開源軟件，以下介紹坐標轉換的兩種方法：投影轉換和仿射變換

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• 投影轉換

這里以xian80經緯度坐標轉xian80，3度分帶 111中央經線平面坐標為例

轉換函數如下：

        Point pointXian80 = projectTransform(lon, lat, "EPSG:4610", "EPSG:2382");

 

    /**
     * 投影轉換， lon=經度，lat=緯度，ESPG格式（例）：EPSG:4610
     */
    public static Point projectTransform(double lon, double lat,
            String epsgSource, String epsgTarget) throws FactoryException,
            MismatchedDimensionException, TransformException {
        // 原始坐標點
        // PS:通常邏輯上理解經度應該是橫坐標x，緯度是y，可是這里經度要填到y，緯度x，否則會報錯
        Point sourcePoint = JtsHelper.createPoint(lat, lon);

        // 定義轉換前和轉換后的投影，可以用ESPG或者wkt
        // "PROJCS[\"Xian_1980_3_Degree_GK_CM_111E\",GEOGCS[\"GCS_Xian_1980\",DATUM[\"D_Xian_1980\",SPHEROID[\"Xian_1980\",6378140.0,298.257]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Gauss_Kruger\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",111.0],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]";
        // CoordinateReferenceSystem mercatroCRS = CRS.parseWKT(strWKTMercator);
        CoordinateReferenceSystem crsSource = CRS.decode(epsgSource);
        CoordinateReferenceSystem crsTarget = CRS.decode(epsgTarget);
        // 投影轉換
        MathTransform transform = CRS.findMathTransform(crsSource, crsTarget);
        Point pointTarget = (Point) JTS.transform(sourcePoint, transform);

        return pointTarget;
    }

關於定義坐標系的說明，GeoTools中定義坐標系有兩種方法，一是坐標系的wkt，二是ESPG
坐標系的wkt可以從arcgis的prj文件中過去，用記事本打開prj文件，里面的內容就是該坐標系的wkt格式內容，例如：PROJCS[\"Xian_1980_3_Degree_GK_CM_111E\",GEOGCS[\"GCS_Xian_1980\",DATUM[\"D_Xian_1980\",SPHEROID[\"Xian_1980\",6378140.0,298.257]],PRIMEM[\"Greenwich\",0.0],UNIT[\"Degree\",0.0174532925199433]],PROJECTION[\"Gauss_Kruger\"],PARAMETER[\"False_Easting\",500000.0],PARAMETER[\"False_Northing\",0.0],PARAMETER[\"Central_Meridian\",111.0],PARAMETER[\"Scale_Factor\",1.0],PARAMETER[\"Latitude_Of_Origin\",0.0],UNIT[\"Meter\",1.0]]

獲取到wkt后，可以通過 CoordinateReferenceSystem mercatroCRS = CRS.parseWKT(strWKTMercator); 獲取到坐標系對象

另一種方法是ESPG，意思是每一個坐標系都有一個ESPG標准的號碼，查詢坐標系的ESPG可通過以下網站 http://spatialreference.org/

PS：當轉換的兩種坐標系的datum不同，會報錯Bursa-Wolf parameters，暫時未解決

 

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• 仿射變換

代碼如下：

首先是輸入三組參考點，前三個是轉換前，后三個是轉換后

最后結果是pointReuslt

        // 參考點坐標
        Coordinate s1 = new Coordinate(429275.549, 2801455.153);
        Coordinate s2 = new Coordinate(428110.626, 2792148.620);
        Coordinate s3 = new Coordinate(428966.479, 2800016.622);

        Coordinate t1 = new Coordinate(4628.339, 801349.338);
        Coordinate t2 = new Coordinate(3515.906, 792036.308);
        Coordinate t3 = new Coordinate(4327.381, 799909.069);
        // 建立仿射變換對象
        AffineTransformationBuilder afb = new AffineTransformationBuilder(s1,
                s2, s3, t1, t2, t3);
        AffineTransformation atf = afb.getTransformation();

        Point pointReuslt = JtsHelper.createPoint(x,y);

        // 坐標轉換
        pointReuslt.apply(atf);