如何在特定边界框的 osmdroid 地图上加载 geoserver WMS 图层？

Question

我正在使用 osmdroid 库在我的应用程序中显示地图视图。我必须在我的 osm 地图中加载 wms 图层以显示村庄边界。

我在谷歌和堆栈溢出上进行搜索，发现以下博客和帖子

1. 如何将 OSMDroid 与私人提供商使用的网络地图服务 (WMS) 配合使用？
2. 带有自定义 wms 图块提供程序的 Android Mapview
3. 在带有 GeoServer 的 Android 应用程序中使用 getTileURL
4. https://osmdroid.github.io/osmdroid/Map-Sources.html
5. < a href="https://docs.geoserver.org/latest/en/user/services/wms/reference.html#getmap" rel="nofollow noreferrer">https://docs.geoserver.org/latest/en/user/services/wms/reference.html#getmap

我引用了这些并尝试实现相同的，我能够在 osm 上加载 wms 层映射成功。但它是在多个循环中加载的，您可以在下图中看到

我希望此 wms 图层仅加载到我在 wms Api url 中传递的提到的边界框中。

我调用 wms 层 api

public class TileProviderFactory {
private static final String TAG = "TileProviderFactory";

private String version = "1.1.0";
private String url = "http://49.206.244.230:8080/geoserver/cfr/wms";
private String layers = "cfr:bastar_villages";

public WMSTileProvider getWmsTileProvider() {

    String[] baseUrl = {url};
    
    final String WMS_FORMAT_STRING =
            url +
                    "?service=WMS" +
                    "&version=" + version +
                    "&request=GetMap" +
                    "&layers=" + layers +
                    "&bbox=81.3445510864258,18.6015472412109,82.2461547851562,19.5618953704834" +
                    "&width=721" +
                    "&height=768" +
                    "&srs=EPSG:4326" +  // NB This is important, other SRS's won't work.
                    "&format=image/png" +
                    "&transparent=true";


    WMSTileProvider tileProvider = new WMSTileProvider(baseUrl, 256) {
        @Override
        public String getTileURLString(long pMapTileIndex) {
            WebMercatorBoundingBox bb = new WebMercatorBoundingBox(MapTileIndex.getX(pMapTileIndex), MapTileIndex.getY(pMapTileIndex), MapTileIndex.getZoom(pMapTileIndex));
            String s = String.format(
                    Locale.ENGLISH,
                    WMS_FORMAT_STRING,
                    bb.getWest(),
                    bb.getSouth(),
                    bb.getEast(),
                    bb.getNorth());
            Log.d(TAG,"Fetching map tile: " + s);
            return s;
        }
    };
    return tileProvider;
}}

WebMercatorBoundingBox 类

public class WebMercatorBoundingBox {
double north;
double south;
double east;
double west;


// Web Mercator n/w corner of the map.
private static final double[] TILE_ORIGIN = {-20037508.34789244,    20037508.34789244};
//array indexes for that data
private static final int ORIG_X = 0;
private static final int ORIG_Y = 1; // "

// Size of square world map in meters, using WebMerc projection.
private static final double MAP_SIZE = 20037508.34789244 * 2;

protected WebMercatorBoundingBox(final int x, final int y, final int zoom) {
    north = tile2lat(y, zoom);
    south = tile2lat(y + 1, zoom);
    west = tile2lon(x, zoom);
    east = tile2lon(x + 1, zoom);
}
double tile2lon(int x, int z) {
    double tileSize = MAP_SIZE / Math.pow(2.0, z);
    return  TILE_ORIGIN[ORIG_X] + x * tileSize;
}

double tile2lat(int y, int z) {
    double tileSize = MAP_SIZE / Math.pow(2.0, z);
    return TILE_ORIGIN[ORIG_Y] - y * tileSize;
}

public double getNorth(){
    return this.north;
}
public double getSouth(){
    return this.south;
}
public double getEast(){
    return this.east;
}
public double getWest(){
    return this.west;
}}

WMSTileProvider 抽象类

public abstract class WMSTileProvider extends OnlineTileSourceBase {

// cql filters
private String cqlString = "";

// Construct with tile size in pixels, normally 256, see parent class.
public WMSTileProvider(String[] baseurl, int tileSizeInPixels) {
    super("WMS tile source", 1 ,19,tileSizeInPixels,"png",baseurl);

}

protected String getCql() {
    return URLEncoder.encode(cqlString);
}

public void setCql(String c) {
    cqlString = c;
}
}

WebMercatorBoundingBox 的代码返回以下边界框（s 的值）：

D/TileProviderFactory: Fetching map tile: http://49.206.244.230:8080/geoserver/cfr/wms?service=WMS&version=1.1.0&request=GetMap&layers=cfr:bastar_villages&bbox=-626172.135872,-1878516.407615,0.000000,-1252344.271743&width=721&height=768&srs=EPSG:4326&format=image/png&transparent=true
D/TileProviderFactory: Fetching map tile: http://49.206.244.230:8080/geoserver/cfr/wms?service=WMS&version=1.1.0&request=GetMap&layers=cfr:bastar_villages&bbox=-626172.135872,626172.135872,0.000000,1252344.271743&width=721&height=768&srs=EPSG:4326&format=image/png&transparent=true
D/TileProviderFactory: Fetching map tile: http://49.206.244.230:8080/geoserver/cfr/wms?service=WMS&version=1.1.0&request=GetMap&layers=cfr:bastar_villages&bbox=-1252344.271743,0.000000,-626172.135872,626172.135872&width=721&height=768&srs=EPSG:4326&format=image/png&transparent=true

请帮助我找出我的错误或给我任何如何实现目标的建议。

Answer 1

您似乎正在使用整个地图边界框来发出平铺请求 - 正如您所看到的http://49.206.244.230:8080/geoserver/cfr/wms?service=WMS&version=1.1.0&request=GetMap&layers=cfr:bastar_villages&bbox=81.34455108 64258,18.6015472412109,82.2461547851562,19.5618953704834&宽度=721&高度=768&srs=EPSG:4326&格式=image/png&透明=true

但是您在每个图块中都要求它，因此您需要计算每个图块的边界（这也会将大小更改为 256x256）。此时，您可能应该在 WebMercator 坐标 (EPSG:3857) 中工作（否则地球的曲率会使数学变得困难）。

这就是我认为 WebMercatorBoundingBox 应该为您提供的内容，因此将这些坐标（它们将在数千到数百万范围内）与 EPSG:3857 的 SRS 相结合应该会返回您所需的图块。使用这些边界后，您需要确保已在 width 和 height 参数中将图块大小正确设置为 265x256，并且 SRS< /code> 也设置正确。

更新

通过查看服务器，您可以使用WGS 图块设置并从以下位置开始计算：

<TileMatrixSet>
  <ows:Identifier>EPSG:4326</ows:Identifier>
  <ows:SupportedCRS>urn:ogc:def:crs:EPSG::4326</ows:SupportedCRS>
  <TileMatrix>
    <ows:Identifier>EPSG:4326:0</ows:Identifier>
    <ScaleDenominator>2.795411320143589E8</ScaleDenominator>
    <TopLeftCorner>90.0 -180.0</TopLeftCorner>
    <TileWidth>256</TileWidth>
    <TileHeight>256</TileHeight>
    <MatrixWidth>2</MatrixWidth>
    <MatrixHeight>1</MatrixHeight>
  </TileMatrix>

然后您将得到纬度/经度并可以使用 EPSG:4326。