For an interactive web application I use Openlayers 4.6.5 with Geoserver 2.13.0.
want to enable dynamic processing of user-selected input data points by using Geoserver WPS. I have extended the WPS functionality with the statistics package from SourceForge and want to run a KernelDensity analysis on a collection of selected points. The result of the KernelDensity process shall be displayed as raster layer in my map.
I am using the Javascript's fetch functionality for sending an XML request to the WPS.:
<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>
Input jsonstring are collected events from selected point data, output should be image/tiff.
However, I am at a loss at how to get a) a raster from the response and b) the raster as layer into my map.
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...
};
I did a very similar thing for the vector-based requests (collectEvents, convexHull) and added the response.json as vector features to the map, which works out fine:
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);
});
};
I fail to find any good documentation on OpenLayers 4 and how to use it with Geoserver WPS. API docs on the use of Raster and Image sources is not really of any help either. I do know about ol.source.ImageWMS, but as I am trying to dynamically generate and display a raster and not retrieve a raster from the WMS, this is no option here.
Is there a way to get the generated raster image from the WPS and display it in the OpenLayers map?
