function filtreStructure() {
	//Recupere la position courante
	var coord=map.getExtent().getCenterLonLat();
	//Le zoom
	var zoom=map.getZoom();
	//Recupere le groupe de structure selectionné
	var idGroupe=jQuery("#nom_grp_structure option:selected").val();
	//Recupere les structures du groupe
	var url='osm/rss_marks.php?id='+idGroupe;
	//Reinitialise la div
	jQuery("#mapOsm").html("");
	//Recharge la map avec les nouvelle données
	init(url);
	//Recentre la map sur la position courante
	this.map.setCenter(coord, zoom);
}

function init(url) {
		map = new OpenLayers.Map ("mapOsm", {
			controls:[
				new OpenLayers.Control.Navigation(),
				new OpenLayers.Control.PanZoom(),
				new OpenLayers.Control.LayerSwitcher()],
			maxExtent: new OpenLayers.Bounds(-20037508.34,-20037508.34,20037508.34,20037508.34),
			maxResolution: 156543.0399,
			numZoomLevels: 19,
			units: 'm',
			projection: new OpenLayers.Projection("EPSG:900913"),
			displayProjection: new OpenLayers.Projection("EPSG:4326"),
		} );

		layerMapnik = new OpenLayers.Layer.OSM.Mapnik("Mapnik");
		layerTilesAtHome = new OpenLayers.Layer.OSM.Osmarender("Osmarender");
		layerCycleMap = new OpenLayers.Layer.OSM.CycleMap("CycleMap");
		
		layerWMS = new OpenLayers.Layer.WMS("OpenLayers WMS",
			"http://labs.metacarta.com/wms/vmap0",
			{layers: 'basic'}
		);
		
		map.addLayers([
			layerMapnik, 
			layerTilesAtHome, layerCycleMap,
			layerWMS]);

		var lonLat = new OpenLayers.LonLat(lon, lat).transform(new OpenLayers.Projection("EPSG:4326"), map.getProjectionObject());
		map.setCenter (lonLat, zoom);
		
		/* ajout des marqueurs */
		layerMarkers = new OpenLayers.Layer.Markers("Markers");
		map.addLayer(layerMarkers);
		jQuery.get(url, {}, function(xml) {
			jQuery("item", xml).each(function(item) {
				var xItem = this;
				agregarMarcador(xItem, layerMarkers, map);
			});
		});

	}