如何從GeoJSON文件中獲取邊界框值？

我有GeoJSON文件。但問題是，我不知道這個文件的投影。現在，我想疊加在我的底圖上（OSM）。我應該怎麼做？這個GeoJSON文件包含斯德哥爾摩地區的功能。我如何設置邊界框？我嘗試了幾個託管站點的openlayers例子。但是，那些不適合我。我得到了一個與我想要的非常相似的例子，從（http://dev.openlayers.org/releases/OpenLayers-2.11/examples/all-overlays.html）。我檢查了他使用邊界框的源代碼。但問題是，如果我刪除邊界框，這個例子不起作用（我與這個給定的數據綁定）。我不知道，我的json文件有什麼問題嗎？貝婁，我提供了一些樣本數據。格式正確嗎？正如我所說的，我嘗試了不同的方式。有一段時間，我從腳本中讀取json文件很好。但是，它不能顯示精選疊加地圖。貝婁，我給了示例代碼，說明我是如何嘗試的。如何從GeoJSON文件中獲取邊界框值？

{ 
"type": "FeatureCollection", 
"features": [ 
{ "type": "Feature", "properties": { "FNODE_": 387603, "TNODE_": 387603, "LPOLY_": 0, "RPOLY_": 0, "LENGTH": 89.206900, "ROADS_SWER": 519006, "ROADS_SW_1": 519006, "REF": "", "TYPE": "residential", "ONEWAY": 8224, "BRIDGE": 8224, "MAXSPEED": 0, "LENGTH_M": 89.500000, "ID": 0, "dist_fnode": 13655.200000, "dist_tnode": 13655.200000 }, "geometry": { "type": "LineString", "coordinates": [ [ 676868.875000, 6569872.000000 ], [ 676882.437500, 6569861.000000 ], [ 676894.062500, 6569851.500000 ], [ 676894.500000, 6569844.500000 ], [ 676891.812500, 6569840.500000 ], [ 676887.312500, 6569841.000000 ], [ 676882.187500, 6569843.000000 ], [ 676875.250000, 6569850.000000 ], [ 676868.125000, 6569858.500000 ], [ 676866.500000, 6569867.000000 ], [ 676868.875000, 6569872.000000 ] ] } } 
, 

{ "type": "Feature", "properties": { "FNODE_": 387723, "TNODE_": 387724, "LPOLY_": 0, "RPOLY_": 0, "LENGTH": 9.581310, "ROADS_SWER": 519163, "ROADS_SW_1": 519163, "REF": "", "TYPE": "service", "ONEWAY": 8224, "BRIDGE": 8224, "MAXSPEED": 0, "LENGTH_M": 9.500000, "ID": 1, "dist_fnode": 13705.100000, "dist_tnode": 13695.600000 }, "geometry": { "type": "LineString", "coordinates": [ [ 677125.375000, 6569906.500000 ], [ 677133.437500, 6569911.500000 ] ] } } 
, 
.. 
.. 
] 
}

代碼示例----

//OSM Layer----------------------------------------------- 
var layer = new OpenLayers.Layer.OSM("Simple OSM Map"); 

//GeoJSON Layer------------------------------------------- 
var vector_format = new OpenLayers.Format.GeoJSON({}); 
var vector_protocol = new OpenLayers.Protocol.HTTP({ 
    url: 'ml/roads.json', 
    format: vector_format 
}); 
var vector_strategies = [new OpenLayers.Strategy.Fixed()]; 
var vector_layer = new OpenLayers.Layer.Vector('More Advanced Vector Layer',{ 
    protocol: vector_protocol, 
    strategies: vector_strategies, 
    isBaseLayer: false 
}); 

var options = { 
    layers: [layer, vector_layer] 
}; 
var map = new OpenLayers.Map("map", options); 
//Projection----------------------------------------------- 
map.setCenter(
    new OpenLayers.LonLat(18.068611, 59.329444).transform(
     new OpenLayers.Projection("EPSG:4326"), 
      map.getProjectionObject() 
    ), 10 
);

謝謝提前。

來源

2012-04-27 Shahjalal

vector_layer.events.on({ 
    loadend: function() { 
     map.zoomToExtent(vector_layer.getDataExtent()); 
    } 
});

我還是覺得你應該設置你的投影在地圖構造...

來源

2012-04-27 11:54:18 tonio

如何從GeoJSON文件中獲取邊界框值？

回答

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