s.addImageryProvider(new Cesium.UrlTemplateImageryProvider({
                url: 'http://{s}.basemaps.cartocdn.com/dark_all/{z}/{x}/{y}.png',
                subdomains: ['a', 'b', 'c', 'd', 'e'],
            }));
            // 设置相机位置
            // earth.camera.position.toString()和earth.camera.toAllJSONStr()这两个方法可获取相机位置
            earth.camera.position = [2.0318085713332255, 0.6906484565329043, 55792.896435757175];
            earth.camera.rotation = [6.128290204901