[GIS] Can QGIS display GeoRSS in real time

gdalgeorssqgis

QGIS has the ability to display GeoRSS by following these steps:

Click on "Add Vector Layer…" icon
Make sure the Data Source is "File" and enter the GeoRSS URL with "/viscurl/" prefix on the GeoRSS (e.g. /vsicurl/http://earthquake.usgs.gov/earthquakes/catalogs/eqs1day-M0.xml).

The problem I'm having is that the canvas is not updated when a new earthquake happens. I have to quit qgis, restart qgis, then load the GeoRSS in order to see any updates.

Anyone knows how to show GeoRSS in real time? I'd love to hear of any other FOSS solutions to this problem.

Best Answer

Reloading a layer was recently discussed on the developers mailing list. From that discussion, the concise answer might be: not for a GeoRSS provider... yet.

The data provider for GeoRSS is probably QgsOgrProvider which does not appear to have the reloadData() method implemented. A search of the /src/providers directory turns up QgsWFSProvider and QgsWmsProvider as having the method. QgsWFSProvider appears to be the only provider with the reloadData() function for vector features (as referenced in the mailing list post by giohappy).

If you want to see new earthquakes, or parse changes over a time span, consider automating the download of the GeoRSS feed (and possibly the loading into a QGIS project file) using Python. Then, load the layers into underdark's excellent TimeManagerPlugin (additional blog posts). Other than that plugin, I don't know of another way to visualize temporal changes in QGIS, at this time.

Related Solutions

[GIS] GeoRSS in Leaflet

Building from the comment by @elrobis here is an example using jQuery for getting the georss and adding simple markers to a map:

<html>
<head>
    <link rel="stylesheet" href="http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.css" />
</head>
<body>
    <div id="map" style="width: 700px; height: 500px"></div>

    <script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>
    <script src="http://cdn.leafletjs.com/leaflet-0.7.3/leaflet.js"></script>

    <script>
        var lat = 39;
        var lng = 17;
        var zoom = 2;
        var map = L.map('map').setView([lat,lng],zoom);

        // set up the ajax call
        function getXML(url) {
            return $.get(url)
        }

        // fire and handle the result
        getXML('http://www.geonames.org/recent-changes.xml').done(function(xml){
            var output = {}; // restructure the xml as an object
            $(xml).find('item').each(function() {
                var nodes = $(this).children();
                $.each(nodes, function(i,node){
                    var name = node.tagName;
                    var value = node.textContent;
                    output[name] = value;
                });
                // build markers from the output and add to the map
                var marker = L.marker([output['georss:point'].split(' ')[0], output['georss:point'].split(' ')[1]]);
                var popupContent = output.description; 
                marker.bindPopup(popupContent)
                marker.addTo(map);
            });
        })

    </script>
</body>
</html>

Best Answer

Related Solutions

[GIS] GeoRSS in Leaflet

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