cesium loupe

var viewer = new Cesium.Viewer('cesiumContainer');

var entity = viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(-111.0, 40.0, 150000.0),
    ellipse : {
        semiMinorAxis : 800000.0,
        semiMajorAxis : 800000.0,
        height: 0,
        material : new Cesium.Color(228, 240, 245, .1),
        outline : true,
        outlineColor : new Cesium.Color(228, 240, 245, .5),
        outlineWidth: 5
    }
});

var handler = new Cesium.ScreenSpaceEventHandler(viewer.canvas);
var dragging = false;
handler.setInputAction(
    function(click) {
        var pickedObject = viewer.scene.pick(click.position);
        if (Cesium.defined(pickedObject) && (pickedObject.id === entity)) {
            entity.ellipse.scale = 1.2;
            dragging = true;
            viewer.scene.screenSpaceCameraController.enableRotate = false;
        }
    },
    Cesium.ScreenSpaceEventType.LEFT_DOWN
);

handler.setInputAction(
    function(movement) {
        if (dragging) {
            entity.position = viewer.camera.pickEllipsoid(movement.endPosition);
        }
    },
    Cesium.ScreenSpaceEventType.MOUSE_MOVE
);

handler.setInputAction(
    function() {
        entity.ellipse.scale = 1;
        dragging = false;
        viewer.scene.screenSpaceCameraController.enableRotate = true;
    },
    Cesium.ScreenSpaceEventType.LEFT_UP
);