Get the geo representation of the current filter box
function(layer) {
		return {
			type: 'rectangle',
			northEast: {
				lat: layer.getBounds()._northEast.lat,
				lng: layer.getBounds()._northEast.lng,
			},
			southWest: {
				lat: layer.getBounds()._southWest.lat,
				lng: layer.getBounds()._southWest.lng,
			}
		};
	}