本文记录获取当前相机中心与地面的射线焦点的方法，可用于视角缩放过程中，控制视角自动平滑切换到二维等场景：

方法一定是视角中心能与地面有交集，如果对着地平线或对着天空肯定是没效果的。直接放代码：

//调整相机到正北方向 上帝视角
const limitViewerController=(viewer)=>{try{viewer.scene.screenSpaceCameraController.enableTilt = false; //禁止中键旋转视角// 将相机朝向正北方向（即Z轴指向正北，Y轴指向正东）var heading = Cesium.Math.toRadians(0.0); // 正北方向为90度var pitch = Cesium.Math.toRadians(0.0); // 保持平面视角var roll = 0.0; // 无滚动var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);let camera_position = viewer.camera.position.clone();let cameraHeight = viewer.camera.positionCartographic.height;let camera = viewer.scene.camera;const rayget = new Cesium.Ray(camera.position, camera.direction)//射线监测 不到目标时 无法设置视角const rayintersection = Cesium.IntersectionTests.rayEllipsoid(rayget, Cesium.Ellipsoid.WGS84);if(rayintersection){const raypoint = Cesium.Ray.getPoint(rayget, rayintersection.start);// 获取当前使用的地球椭球体var ellipsoid = viewer.scene.globe.ellipsoid;// 将Cartesian3转换为经纬度var raycartographic = ellipsoid.cartesianToCartographic(raypoint);var cameracartographic = ellipsoid.cartesianToCartographic(camera_position);// 获取经度、纬度和高度var raylongitude = Cesium.Math.toDegrees(raycartographic.longitude);var raylatitude = Cesium.Math.toDegrees(raycartographic.latitude);var rayheight = cameracartographic.height;const destinationPostion = Cesium.Cartesian3.fromDegrees(raylongitude, raylatitude, rayheight+100000);viewer.camera.flyTo({destination : destinationPostion,duration: 1.5,orientation : {heading : 6.283185307179586,pitch : -1.5707963267948966,roll : 0.0}});}//调整也可以通过TWEEN.js 实现过渡动画//import * as TWEEN from '@tweenjs/tween.js'// const coords = {x: viewer.camera.heading, y: viewer.camera.pitch,z:viewer.camera.roll} // Start at (0, 0)// const tween = new TWEEN.Tween(coords, false) // Create a new tween that modifies 'coords'.// .to({x: 6.283185307179586, y: -1.5707963267948966, z:0}, 1000) // .easing(TWEEN.Easing.Quadratic.InOut)// .onUpdate((object) => {// 	viewer.camera.setView({// 		//destination : new Cesium.Cartesian3(raypoint.x, raypoint.y, camera_position.z),// 	    orientation: {// 			heading: object.x, // 方向的朝向，以弧度为单位// 			pitch: object.y, // 视角的高度，以弧度为单位// 	        roll: object.z // 绕着圆周运动的角度，一般设置为0// 	    }// 	});// 	// viewer.scene.camera.setView({// 	// 	 destination : new Cesium.Cartesian3(camera_position.x, camera_position.y, camera_position.z),// 	//     orientation: {// 	//         headingPitchRoll: new Cesium.HeadingPitchRoll(object.x, object.y, object.z)// 	//     }// 	// });// })// .start() // Start the tween immediately.// function animate() {// 	tween.update()// 	requestAnimationFrame(animate)// }// requestAnimationFrame(animate)}catch(err){console.log(err);}
}