Question

注意：我知道还有另一个与此类似的问题，但尚未得到解答，我需要知道如何使用GeoJSON和OSM处理混合投影。

我很困惑。我在Android上使用OSMDroid API进行映射，并希望使用OpenLayers和GeoExt复制它，但我有一个包含GeoJSON节点和动作事件的投影问题。

我的磁贴集基于OSM，并且与此HTML / JS位于同一Web服务器上。请在下面查看。我意识到我的界限不起作用，我的预测可能完全错误。我一直在测试不同的组合。

问题是我的地图显示正确并且居中。但是：

我的GeoJSON功能节点远离地图。它们处于不同的投影长/纬度，但我不知道如何将GeoJSON long / lat设置或转换为当前地图投影。
我的mapCtrl不起作用。当我点击它时，lonlat是另一个投影（OSM投影坐标），我似乎无法转换它们。
非常感谢任何有关范围/范围实际工作的提示

有人可以请一点投射建议吗？叹息......我对此没有足够的耐心。

enter image description here

这是我的完整JS，原样：

var mapPanel, store, gridPanel, mainPanel, nodePop, mapPop;

Ext.onReady(function() {

    var map, mapLayer, vecLayer;
    var lon = -70.885610;
    var lat = 38.345822;
    var zoom = 17;
    var maxZoom = 18;

var toProjection = new OpenLayers.Projection("EPSG:4326");
var fromProjection = new OpenLayers.Projection("EPSG:900913");
    var extent = new OpenLayers.Bounds(-1.32,51.71,-1.18,51.80).transform(fromProjection, toProjection);

    // Setup the node layer feature store and push it all into a vector layer
    vecLayer = new OpenLayers.Layer.Vector("vector");
    store = new GeoExt.data.FeatureStore({
        layer: vecLayer,
        fields: [
            {name: 'name', type: 'string'},
            {name: 'status', type: 'string'}
        ],
        proxy: new GeoExt.data.ProtocolProxy({
            protocol: new OpenLayers.Protocol.HTTP({
                url: "data/sa.json",
                format: new OpenLayers.Format.GeoJSON()
            })
        }),
        autoLoad: true
    });

    // Setup the basic map layer using OSM style tile retreival to pull tiles
    // from the same server hosting this service
    map = new OpenLayers.Map(
        'map', {
            controls:[
                new OpenLayers.Control.Navigation(),
                new OpenLayers.Control.PanZoomBar(),
                new OpenLayers.Control.Attribution(),
                new OpenLayers.Control.ScaleLine()],
            projection: toProjection,
            displayProjection: fromProjection,
            numZoomLevels: 20,
            fractionalZoom: true
        });

    mapLayer = new OpenLayers.Layer.OSM(
        "Local Tiles",
        "tiles/${z}/${x}/${y}.png",
        {
            zoomOffset: 17,
            resolutions: [1.194328566741945,0.5971642833709725,0.2985821416854863] // Zoom level 17 - 19
        });

    map.addLayers([mapLayer, vecLayer]);

    // Create a map panel
    mapPanel = new GeoExt.MapPanel({
            title: "Map",
            region: "center",
            map: map,
            xtype: "gx_mappanel",
            center: new OpenLayers.LonLat(lon, lat),
            zoom: zoom
    });

    // Create a grid panel for listing nodes
    gridPanel = new Ext.grid.GridPanel({
            title: "Nodes",
            region: "east",
            store: store,
            width: 275,
            columns: [{
                header: "Name",
                width: 200,
                dataIndex: "name"
            }, {
                header: "Status",
                width: 75,
                dataIndex: "status"
            }],
            sm: new GeoExt.grid.FeatureSelectionModel({
                autoPanMapOnSelection: true
                })
    });

    // Create the main view port
    new Ext.Viewport({
        layout: "border",
        items: [{
            region: "north",
            contentEl: "title",
            height: 150
        }, mapPanel, gridPanel]
    });
    var lonLat = new OpenLayers.LonLat(lon, lat).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());
    map.setCenter(lonLat, zoom);


    // Attach all the event driven stuff here...
    // Create a node selection pop up control
    function nodeAction(feature) {
        nodePop = new GeoExt.Popup({
            title: 'Node selected',
            location: feature,
            width: 200,
            html: "",
            maximizable: true,
            collapsible: true
        });
        nodePop.on({
            close: function() {
                if(OpenLayers.Util.indexOf(vectorLayer.selectedFeatures, this.feature) > -1) {
                    selectCtrl.unselect(this.feature);
                }
            }
        });
        nodePop.show();
    };

    // Attach the pop to node/feature selection events
    var selectCtrl = new OpenLayers.Control.SelectFeature(vecLayer);
    vecLayer.events.on({
        featureselected: function(e) {
            nodeAction(e.feature);
        }
    });

    // Create map selection pop up control
    function mapAction(lonlat) {
        mapPop = new GeoExt.Popup({
            title: 'Map selected',
            location: lonlat,
            width: 200,
            html: "You clicked on (" + lonlat.lon.toFixed(2) + ", " + lonlat.lat.toFixed(2) + ")",
            maximizable: true,
            collapsible: true,
            map: mapPanel.map,
            anchored: true
        });
        mapPop.doLayout();
        mapPop.show();
    };

    var mapCtrl = new OpenLayers.Control.Click({
        trigger: function(evt) {
            var lonlat = mapPanel.map.getLonLatFromViewPortPx(evt.xy);
            lonlat.transform(new OpenLayers.Projection("EPSG:4326"), mapPanel.map.getProjectionObject());

            //.transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());

            mapAction(lonlat);
        }
    });
    mapPanel.map.addControl(mapCtrl);
    mapCtrl.activate();
});

// A control to handle user clicks on the map
OpenLayers.Control.Click = OpenLayers.Class(
    OpenLayers.Control, {
        defaultHandlerOptions: {
            single: true,
            double: false,
            pixelTolerance: 0,
            stopSingle: true
        },
        initialize: function(options) {
            this.handlerOptions = OpenLayers.Util.extend(
                options && options.handlerOptions || {},
                this.defaultHandlerOptions
            );
            OpenLayers.Control.prototype.initialize.apply(
                this, arguments
            );
            this.handler = new OpenLayers.Handler.Click(
                this,
                { click: this.trigger },
                this.handlerOptions
            );
        },
        CLASS_NAME: "OpenLayers.Control.Click"
    }
);

这是我正在使用的GeoJSON：

{
  "type": "FeatureCollection",
  "features": [
    {
      "geometry": {
        "type": "Point",
        "coordinates": [
          -70.3856,
      38.3458
        ]
      },
      "type": "Feature",
      "properties": {
        "name": "Node0",
        "status": "Active",
        "externalGraphic": "img/node2.png",
        "graphicHeight": 75, "graphicWidth": 75
      },
      "id": 100
    },
    {
      "geometry": {
        "type": "Point",
        "coordinates": [
          -70.885810,
      38.344722
        ]
      },
      "type": "Feature",
      "properties": {
        "name": "Node1",
        "status": "Active",
        "externalGraphic": "img/node2.png",
        "graphicHeight": 75, "graphicWidth": 75
      },
      "id": 101
    }
  ]
}

Answer 1

好的，这就是我处理这个问题的方法：

我在我的后端使用嵌入式Jetty Web服务器，但是无论如何，我创建了一个servlet来响应GeoJSON格式的数据。每个要素位置lon / lat在投影之间转换。（例如EPSG：4326至EPSG：900913）
lon / lat投影对话利用了GeoTools Java API。这篇博文特别有用（http://ariasprado.name/2012/08/13/quick-and-dirty-coordinate-transforming-using-geotools.html）请注意，如果您需要经过相当多的反复试验你只想包括转换你所需的罐子预测。 GeoTools很大，做了很多，而且有很多广口瓶中。

现在，当GeoExt.data.ProtocolProxy加载我的GeoJSON内容时，它已经在OSM兼容的EPSG：900913中。我本来希望在GeoExt / OpenLayer中完全处理这个问题，但似乎没有一个简单的方法。我将承认GeoExt和OpenLayers没有超级好的参考文档可供使用。

我将包含我的GeoTools代码，但上面的“Arias Prado GIS Ramblings”博客文章比我做得更好。但是，请注意，您必须对罐子进行试验和错误。投影编码器是动态加载的，而它们又与其他jar类具有类依赖关系。

Openlayers使用OSM样式贴图和GeoJSON矢量图层进行投影

1 个答案: