java转换投影坐标_GeoTools坐标转换（投影转换和仿射变换）
GeoTools是在java下的gis开源软件，以下介绍坐标转换的两种方法：投影转换和仿射变换
投影转换
这里以xian80经纬度坐标转xian80，3度分带 111中央经线平面坐标为例
转换函数如下：
1 Point pointXian80 = projectTransform(lon, lat, "EPSG:4610", "EPSG:2382");
1 /**
2 * 投影转换， lon=经度，lat=纬度，ESPG格式(例)：EPSG:46103 */
4 public static Point projectTransform(double lon, doublelat,5 String epsgSource, String epsgTarget) throwsFactoryException,6 MismatchedDimensionException, TransformException {7 //原始坐标点8 //PS:通常逻辑上理解经度应该是横坐标x，纬度是y，可是这里经度要填到y，纬度x，否则会报错
9 Point sourcePoint =JtsHelper.createPoint(lat, lon);10
11 //定义转换前和转换后的投影，可以用ESPG或者wkt12 //"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]]";13 //CoordinateReferenceSystem mercatroCRS = CRS.parseWKT(strWKTMercator);
14 CoordinateReferenceSystem crsSource =CRS.decode(epsgSource);15 CoordinateReferenceSystem crsTarget =CRS.decode(epsgTarget);16 //投影转换
17 MathTransform transform =CRS.findMathTransform(crsSource, crsTarget);18 Point pointTarget =(Point) JTS.transform(sourcePoint, transform);19
20 returnpointTarget;21 }
关于定义坐标系的说明，GeoTools中定义坐标系有两种方法，一是坐标系的wkt，二是ESPG
坐标系的wkt可以从arcgis的prj文件中过去，用记事本打开prj文件，里面的内容就是该坐标系的wkt格式内容，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]]
获取到wkt后，可以通过 CoordinateReferenceSystem mercatroCRS = CRS.parseWKT(strWKTMercator); 获取到坐标系对象
另一种方法是ESPG，意思是每一个坐标系都有一个ESPG标准的号码，查询坐标系的ESPG可通过以下网站 外链网址已屏蔽
PS：当转换的两种坐标系的datum不同，会报错Bursa-Wolf parameters，暂时未解决
仿射变换
代码如下：
首先是输入三组参考点，前三个是转换前，后三个是转换后
最后结果是pointReuslt
1 //参考点坐标
2 Coordinate s1 = new Coordinate(429275.549, 2801455.153);3 Coordinate s2 = new Coordinate(428110.626, 2792148.620);4 Coordinate s3 = new Coordinate(428966.479, 2800016.622);5
6 Coordinate t1 = new Coordinate(4628.339, 801349.338);7 Coordinate t2 = new Coordinate(3515.906, 792036.308);8 Coordinate t3 = new Coordinate(4327.381, 799909.069);9 //建立仿射变换对象
10 AffineTransformationBuilder afb = newAffineTransformationBuilder(s1,11 s2, s3, t1, t2, t3);12 AffineTransformation atf =afb.getTransformation();13
14 Point pointReuslt =JtsHelper.createPoint(x,y);15
16 //坐标转换
17 pointReuslt.apply(atf);