title: Shape is not getting plotted on the map image generated
body: <p>I am trying to create map image from the attached JSON the image shows correct location but does not plot polygon.</p>
  
  <p>This is happening only in case of one feature having circle shape whereas for other shapes they are rendered fine.</p>
  
  <p>Following function is used to create image from json.</p>
  
  <pre><code>    public static Image CreateMapImage(string json, 
                  KnownTileSource baseMapTile = KnownTileSource.BingRoads)
              {
                  double maxX = Double.MinValue,
                      maxY = Double.MinValue,
                      minX = Double.MaxValue,
                      minY = Double.MaxValue;
  
                  var map = new SharpMap.Map(new Size(800, 400));
                  map.Layers.Add(new TileLayer(
                      KnownTileSources.Create(
                          baseMapTile, bingKey), "BingRoad"));
  
                  JObject rss = JObject.Parse(json);
                  foreach (JObject shape in rss["features"])
                  {
                      var jsonReader = new NetTopologySuite.IO.GeoJsonReader();
                      var geom = jsonReader.Read&lt;IGeometry&gt;(shape.ToString(Formatting.None));
  
                      var fp = new GeometryFeatureProvider(geom);
                      var layer = new VectorLayer("geojson", fp);
  
                      layer.CoordinateTransformation = new
                          CoordinateTransformationFactory().CreateFromCoordinateSystems(
                              GeographicCoordinateSystem.WGS84,
                              ProjectedCoordinateSystem.WebMercator);
  
                      layer.Style = new SharpMap.Styles.VectorStyle()
                      {
                          Fill = new SolidBrush(Color.FromArgb(100, 255, 0, 0)),
                          Outline = new Pen(Color.Red, 1.5f),
                          EnableOutline = true
                      };
  
                      maxX = layer.Envelope.MaxX &gt; maxX ? layer.Envelope.MaxX : maxX;
                      maxY = layer.Envelope.MaxY &gt; maxY ? layer.Envelope.MaxY : maxY;
                      minX = layer.Envelope.MinX &lt; minX ? layer.Envelope.MinX : minX;
                      minY = layer.Envelope.MinY &lt; minY ? layer.Envelope.MinY : minY;
  
                      map.Layers.Add(layer);
                  }
  
                  map.ZoomToBox(new Envelope(new GeoPoint(m
  
  inX, minY), new GeoPoint(maxX, maxY)));
                  map.Zoom *= 1.1;
  
                  return map.GetMap();
              }
  </code></pre>
  
  <p>I am using following Geojson file to render the shape </p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-js lang-js prettyprint-override"><code>{
   "features": [{
     "id": "4",
     "geometry": {
      "coordinates": [[[73.879909, 18.521356], [73.879617, 18.526641], [73.878744, 18.531869], [73.877299, 18.53698], 
      [73.875299, 18.541921], [73.872765, 18.546636], [73.869725, 18.551074], [73.866212, 18.555186], [73.862265, 18.558928], 
      [73.857928, 18.562258], [73.853246, 18.56514], [73.848273, 18.567542], [73.843062, 18.569438], [73.837671, 18.570808], 
      [73.832158, 18.571635], [73.826584, 18.571912], [73.82101, 18.571635], [73.815497, 18.570808], [73.810105, 18.569438], 
      [73.804894, 18.567542], [73.799921, 18.56514], [73.79524, 18.562258], [73.790902, 18.558928], [73.786955, 18.555186], 
      [73.783442, 18.551074], [73.780402, 18.546636], [73.777868, 18.541921], [73.775868, 18.53698], [73.774423, 18.531869], 
      [73.77355, 18.526641], [73.773258, 18.521356], [73.77355, 18.516071], [73.774423, 18.510843], [73.775868, 18.50573], 
      [73.777868, 18.500789], [73.780402, 18.496072], [73.783442, 18.491633], [73.786955, 18.487519], [73.790902, 18.483776], 
      [73.79524, 18.480444], [73.799921, 18.477561], [73.804894, 18.475158], [73.810105, 18.47326], [73.815497, 18.47189], 
      [73.82101, 18.471062], [73.826584, 18.470785], [73.832158, 18.471062], [73.837671, 18.47189], [73.843062, 18.47326], 
      [73.848273, 18.475158], [73.853246, 18.477561], [73.857928, 18.480444], [73.862265, 18.483776], [73.866212, 18.487519], 
      [73.869725, 18.491633], [73.872765, 18.496072], [73.875299, 18.500789], [73.877299, 18.50573], [73.878744, 18.510843], 
      [73.879617, 18.516071], [73.879909, 18.521356]]],
      "type": "Polygon",
      "bbox": [73.773258, 18.470785, 73.879909, 18.571912]
     },
     "properties": {
      "status": "add",
      "editable": "true",
      "color": {
       "r": 0,
       "g": 255,
       "b": 255,
       "a": 0.45
      },
      "border": {
       "b": 255,
       "g": 255,
       "r": 0,
       "a": 1
      },
      "OBJECTID": "4"
     },
     "type": "Feature",
     "bbox": [73.773258, 18.470785, 73.879909, 18.571912]
    }
   ],
   "type": "FeatureCollection"
  }</code></pre>
  </div>
  </div>
  </p>