兰伯特等角圆锥地图投影在java中获取网格的x，y值

发布于 2024-08-01 16:31:50 字数 1676 浏览 4 评论 0原文

我正在使用 unidata 中的 NetCDF 4 java 库来读取 GRIB2 文件，现在正在尝试找到一种方法获取给定纬度/经度的时区偏移量。我有一个北半球的 .flt 文件，其中包含所有这些信息，我知道如何阅读它，我只是不知道如何正确进行地图投影。我可以使用进行投影 LambertConformal(originLat, originLon, stdParallel1, stdParallel2) 但我不知道如何使用网格内的投影 x,y 值。

网格值为 Nx=1073 和 Ny=689，我得到的 lat=33.92、lon=-84.33 的投影值是 x=995 y=1035。我知道投影值是正确的，但我不知道如何用它们读取网格。

也许有人也可以帮助我理解以下价值观。

 :grid_mapping_name = "lambert_conformal_conic"; 
   ：标准并行= 25.0；   // 双倍的 
   :中央子午线经度 = 265.0;   // 双倍的 
   ：投影原点纬度 = 25.0；   // 双倍的 
   :earth_shape = "地球球形，半径由生产者指定"; 
   :spherical_earth_radius_meters = 6371200.0;   // 双倍的 
   :GRIB_param_Dx = 5079.4062;   // 双倍的 
   :GRIB_param_Dy = 5079.4062;   // 双倍的 
   :GRIB_param_GDSkey = 1158554943;   // 整数 
   ：GRIB_param_La1 = 20.192；   // 双倍的 
   :GRIB_param_LaD = 25.0;   // 双倍的 
   :GRIB_param_Latin1 = 25.0;   // 双倍的 
   :GRIB_param_Latin2 = 25.0;   // 双倍的 
   ：GRIB_param_Lo1 = 238.446；   // 双倍的 
   ：GRIB_param_LoV = 265.0；   // 双倍的 
   :GRIB_param_NpProj = "真"; 
   :GRIB_param_Nx = 1073;   // 整数 
   :GRIB_param_Ny = 689;   // 整数 
   :GRIB_param_ProjFlag = 0;   // 整数 
   :GRIB_param_Quasi = "假"; 
   :GRIB_param_ResCompFlag = 0;   // 整数 
   :GRIB_param_SpLat = -90.0;   // 双倍的 
   :GRIB_param_SpLon = 0.0;   // 双倍的 
   :GRIB_param_Winds = "真"; 
   :GRIB_param_grid_name = "兰伯特等形"; 
   :GRIB_param_grid_radius_spherical_earth = 6371200.0;   // 双倍的 
   :GRIB_param_grid_shape = "地球球形，半径由生产者指定"; 
   :GRIB_param_grid_shape_code = 1;   // 整数 
   :GRIB_param_grid_type = 30;   // 整数 
   :GRIB_param_grid_units = "米";

原文

I am using the NetCDF 4 java library from unidata to read GRIB2 files and am now trying to find a way to get timezone offsets for a given latitude/longitude. I have a .flt file for the northern hemisphere that contains all of this information and I know how to read it, I just don't know how to do the map projection properly. I am able to do the projection using
LambertConformal(originLat, originLon, stdParallel1, stdParallel2) but I do not know how to use the projected x,y values inside the grid.

The grid values are Nx=1073 and Ny=689 and the projected values I'm getting for lat=33.92, lon=-84.33 are x=995 y=1035. I know the projected values are right, but I don't know how to read the grid with them.

Maybe someone can help me understand the following values, too.

 :grid_mapping_name = "lambert_conformal_conic";
 :standard_parallel = 25.0; // double
 :longitude_of_central_meridian = 265.0; // double
 :latitude_of_projection_origin = 25.0; // double
 :earth_shape = "Earth spherical with radius specified by producer";
 :spherical_earth_radius_meters = 6371200.0; // double
 :GRIB_param_Dx = 5079.4062; // double
 :GRIB_param_Dy = 5079.4062; // double
 :GRIB_param_GDSkey = 1158554943; // int
 :GRIB_param_La1 = 20.192; // double
 :GRIB_param_LaD = 25.0; // double
 :GRIB_param_Latin1 = 25.0; // double
 :GRIB_param_Latin2 = 25.0; // double
 :GRIB_param_Lo1 = 238.446; // double
 :GRIB_param_LoV = 265.0; // double
 :GRIB_param_NpProj = "true";
 :GRIB_param_Nx = 1073; // int
 :GRIB_param_Ny = 689; // int
 :GRIB_param_ProjFlag = 0; // int
 :GRIB_param_Quasi = "false";
 :GRIB_param_ResCompFlag = 0; // int
 :GRIB_param_SpLat = -90.0; // double
 :GRIB_param_SpLon = 0.0; // double
 :GRIB_param_Winds = "True";
 :GRIB_param_grid_name = "Lambert Conformal";
 :GRIB_param_grid_radius_spherical_earth = 6371200.0; // double
 :GRIB_param_grid_shape = "Earth spherical with radius specified by producer";
 :GRIB_param_grid_shape_code = 1; // int
 :GRIB_param_grid_type = 30; // int
 :GRIB_param_grid_units = "m";

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