将属性添加到GeoJSON

Question

我有一个令人兴奋的GeoJSON文件，像这样;

{ 
    "type": "FeatureCollection", 
    "crs": { 
    "type": "name", 
    "properties": { 
     "name": "urn:ogc:def:crs:OGC:1.3:CRS84" 
    } 
    }, 
    "features": [ 
    { 
     "type": "Feature", 
     "properties": { 
     "Item": "Value" 
     }, 
     "geometry": { 
     "type": "Polygon", 
     "coordinates": [ 
      [ 
      [ 
       9.449194065548566, 
       55.86046393906458, 
       -999 
      ], 
      [ 
       9.460203211292942, 
       55.8619238071893, 
       -999 
      ], 
      [ 
       9.440463307997378, 
       55.876740797773365, 
       -999 
      ] 
      ] 
     ] 
     } 
    }, 
    { 
     "type": "Feature", 
     "properties": { 
     "Item": "Value" 
     }, 
     "geometry": { 
     "type": "Polygon", 
     "coordinates": [ 
      [ 
      [ 
       8.59655725301728, 
       55.53506085541584, 
       -999 
      ], 
      [ 
       8.601439658322603, 
       55.52856219238175, 
       -999 
      ] 
      ] 
     ] 
     } 
    } 
    ] 
} 

我需要加载该文件，将属性添加到每个特征，并将其保存为一个新的JSON文件。 什么是在C＃中最好的方法呢？

我可以像这样加载文件;

using (StreamReader r = new StreamReader(Server.MapPath("~/test.json"))) 
     { 
      string json = r.ReadToEnd(); 
      List<RootObject> ro = JsonConvert.DeserializeObject<List<RootObject>>(json); 
     } 

但是，那又如何？

Answer 1

您可以使用GDAL/OGR的OGR库部分读取geojson文件。 OGR能够直接读取GeoJSON格式导出： http://gdal.org/1.11/ogr/drv_geojson.html

不幸为C＃GDAL/OGR绑定的文档是相当差。

但是你可以对如何使用OGR访问GeoJSON的功能在此示例中看看：

https://trac.osgeo.org/gdal/browser/trunk/gdal/swig/csharp/apps/OGRFeatureEdit.cs

所以，你可以使用：

Ogr.RegisterAll(); // To register the OGR drivers especially geojson 
DataSource ds = Ogr.Open(<path to your geojson>, 1); 
Layer layer = ds.GetLayerByName("the name of the layer"); 

// Finally iterate over all features you want to modify 
Feature feature = layer.GetFeature(0); 
feature.SetField(<set your fields>); 

// write your feature back to your layer 
layer.SetFeature(feature)