Openlayers4 中 Geoserver WPS 的显示栅格结果

Posted 2023-03-25

【中文标题】Openlayers4 中 Geoserver WPS 的显示栅格结果

【英文标题】：Displayer raster result from Geoserver WPS in Openlayers4

【发布时间】：2018-05-17 09:15:08

【问题描述】：

对于交互式网络应用程序，我使用 Openlayers 4.6.5 和 Geoserver 2.13.0。

希望通过使用 Geoserver WPS 启用用户选择的输入数据点的动态处理。我使用 SourceForge 的统计数据包扩展了 WPS 功能，并希望对选定点的集合运行 KernelDensity 分析。 KernelDensity 处理的结果将在我的地图中显示为栅格图层。

我正在使用 javascript 的 fetch 功能向 WPS 发送 XML 请求。：

<wps:Execute version="1.0.0" service="WPS" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:wfs="http://www.opengis.net/wfs" xmlns:wps="http://www.opengis.net/wps/1.0.0" xmlns:ows="http://www.opengis.net/ows/1.1" xmlns:gml="http://www.opengis.net/gml" xmlns:ogc="http://www.opengis.net/ogc" xmlns:xlink="http://www.w3.org/1999/xlink" xsi:schemaLocation="http://www.opengis.net/wps/1.0.0 http://schemas.opengis.net/wps/1.0.0/wpsAll.xsd"><ows:Identifier>statistics:KernelDensity</ows:Identifier><wps:DataInputs><wps:Input><ows:Identifier>inputFeatures</ows:Identifier><wps:Data><wps:ComplexData mimeType="application/json"><![CDATA["type":"FeatureCollection","totalFeatures":2,"features":["type":"Feature","id":"alllocations.fid-57f369ef_1636c6c3947_-5ddb","geometry":"type":"Point","coordinates":[100.330936,5.41626549],"geometry_name":"geom","properties":"idstorylocation":344,"idstory":27,"story":"HOUN","idlocation":203,"location_role":"reference","actions":"The walking stick left behind by young Dr Mortimer is of the sort which is called \"Penang Lawyer\".","name":"Penang ","country_today":"Malaysia","reference_to":"city","reality":"real","certainty":"good","accuracy":"high","county":"","state_country":"","city":"Penang","idcountry":298,"idpoints":99,"idperson":40,"initial":null,"lastname":"Mortimer","firstname":"James","nationality":null,"type":"Feature","id":"alllocations.fid-57f369ef_1636c6c3947_-5dda","geometry":"type":"Point","coordinates":[100.330936,5.41626549],"geometry_name":"geom","properties":"idstorylocation":1519,"idstory":15,"story":"SILV","idlocation":203,"location_role":"reference","actions":"The stick of Fitzroy Simpson, which was a Penang-lawyer weighted with lead, was was just such a weapon as might, by repeated blows, have inflicted the terrible injuries to which the trainer had succumbed. ","name":"Penang ","country_today":"Malaysia","reference_to":"city","reality":"real","certainty":"good","accuracy":"high","county":"","state_country":"","city":"Penang","idcountry":298,"idpoints":99,"idperson":0,"initial":null,"lastname":null,"firstname":null,"nationality":null],"crs":"type":"name","properties":"name":"urn:ogc:def:crs:EPSG::4326"]]></wps:ComplexData></wps:Data></wps:Input><wps:Input><ows:Identifier>kernelType</ows:Identifier><wps:Data><LiteralData>Quadratic</LiteralData></wps:Data></wps:Input><wps:Input><ows:Identifier>populationField</ows:Identifier><wps:Data><wps:LiteralData>icount</wps:LiteralData></wps:Data></wps:Input><wps:Input><ows:Identifier>searchRadius</ows:Identifier><wps:Data><wps:LiteralData>5</wps:LiteralData></wps:Data></wps:Input><wps:Input><ows:Identifier>cellSize</ows:Identifier><wps:Data><wps:LiteralData>20</wps:LiteralData></wps:Data></wps:Input><wps:Input><ows:Identifier>extent</ows:Identifier><wps:Data><wps:BoundingBoxData crs="EPSG:4326" dimension="2"><ows:LowerCorner>-180.0 -90.0</ows:LowerCorner><ows:UpperCorner>180.0 90.0</ows:UpperCorner></wps:BoundingBoxData></wps:Data></wps:Input></wps:DataInputs><wps:ResponseForm><wps:RawDataOutput mimeType="image/tiff"><ows:Identifier>result</ows:Identifier></wps:RawDataOutput></wps:ResponseForm></wps:Execute>

输入jsonstring是从选定点数据中收集的事件，输出应该是image/tiff。

但是，我不知道如何从响应中获取 a) 栅格和 b) 栅格作为图层到我的地图中。

function calculateKernelDensity(jsonstring)

xml = createKernelDensityRequest(jsonstring);

fetch('http://localhost:8080/geoserver/Sherlock/wps', 
    method: 'POST',
    body: xml
)
// tried my luck with blob to use it later on as image layer
.then(function(response)
    var blob = response.blob(); 
    return blob;
)
.then(function(blob)
    console.log(blob.size + " " + blob.type);
);
// something here to put it as layer into the map...
;  

我对基于矢量的请求（collectEvents、convexHull）做了非常相似的事情，并将 response.json 作为矢量特征添加到地图中，效果很好：

function collectEvents(jsonstring)

xml = createCollectEventsRequest(jsonstring);

fetch('http://localhost:8080/geoserver/Sherlock/wps',
    method: 'POST',
    body: xml
)
.then(function(response)
    jsonresults = response.json();
    return jsonresults;
)
.then(function(jsonresults)
    jsonstring = JSON.stringify(jsonresults);
    results = new ol.format.GeoJSON(geometryName:'geom').readFeatures(jsonresults,
        dataProjection: 'EPSG:4326',
        featureProjection: 'EPSG:3857'
    );
    vectorSource.clear(results);
    vectorSource.addFeatures(results);
);
;

我找不到任何关于 OpenLayers 4 以及如何将其与 Geoserver WPS 一起使用的好的文档。关于使用光栅和图像源的 API 文档也没有任何帮助。我确实知道 ol.source.ImageWMS，但是当我尝试动态生成和显示栅格而不是从 WMS 检索栅格时，这里没有选择。

有没有办法从 WPS 中获取生成的光栅图像并将其显示在 OpenLayers 地图中？

【参考方案1】：

从this question 的回答来看，无法在 OpenLayers 中直接显示 GeoTiff，因为它使用浏览器的原生显示功能进行显示。

可能对您有用的一个选项是将 WPS 输出保存到 GeoServer，然后使用 WMS 请求获取结果。 GeoSolution's WPS training 中有一个如何执行此操作的示例。此answer 还为此目的提到了StoreCoverage 进程，但我找不到任何其他参考。