[Cesium中文网]可视分析专题

基于Cesium的简单可视域分析 https://blog.csdn.net/fengyekafei/article/details/90212714?tdsourcetag=s_pcqq_aiomsg

源代码如下：

// 加载3dtile模型
var tileset = new Cesium.Cesium3DTileset({
	url: ''
});
viewer.scene.primitives.add(tileset);
 
// 观察点
var viewPoint = Cesium.Cartesian3.fromDegrees(114.46430512179235, 30.436947239947525, 100);
 
// 世界坐标转换为投影坐标
var webMercatorProjection = new Cesium.WebMercatorProjection(viewer.scene.globe.ellipsoid);
var viewPointWebMercator = webMercatorProjection.project(Cesium.Cartographic.fromCartesian(viewPoint));
 
// 目标点集合
var destPoints = [];
 
// 观察点和目标点的距离
var radius = 1000; // 视距1000米
 
// 计算45°和135°之间的目标点
for (var i = 45; i <= 135; i++) {
	// 度数转弧度
	var radians = Cesium.Math.toRadians(i);
	// 计算目标点
	var toPoint = new Cesium.Cartesian3(viewPointWebMercator.x + radius * Math.cos(radians), viewPointWebMercator.y + radius * Math.sin(radians), 30);
	// 投影坐标转世界坐标
	toPoint = webMercatorProjection.unproject(toPoint);
	destPoints.push(Cesium.Cartographic.toCartesian(toPoint.clone()));
}
 
// 绘制线
function drawLine(leftPoint, secPoint, color) {
	viewer.entities.add({
		polyline: {
			positions: [leftPoint, secPoint],
			arcType: Cesium.ArcType.NONE,
			width: 5,
			material: color,
			depthFailMaterial: color
		}
	})
}
 
// 一定要等3dtile模型加载完成后执行
setTimeOut(function(){
	pickFromRay();
}, 2000)
 
function pickFromRay() {
	for (var i = 0; i < destPoints.length; i++) {
		// 计算射线的方向，目标点left 视域点right
		var direction = Cesium.Cartesian3.normalize(Cesium.Cartesian3.subtract(destPoints[i], viewPoint, new Cesium.Cartesian3()), new Cesium.Cartesian3());
		// 建立射线
		var ray = new Cesium.Ray(viewPoint, direction);
		var result = viewer.scene.pickFromRay(ray, objectsToExclude); // 计算交互点，返回第一个
		showIntersection(result, destPoints[i], viewPoint);
	}
}
 
// 处理交互点
function showIntersection(result, destPoint, viewPoint) {
	// 如果是场景模型的交互点，排除交互点是地球表面
	if (Cesium.defined(result) && Cesium.defined(result.object)) {
		drawLine(result.position, viewPoint, Cesium.Color.GREEN); // 可视区域
		drawLine(result.position, destPoint, Cesium.Color.RED); // 不可视区域
	} else {
		drawLine(viewPoint, destPoint, Cesium.Color.GREEN);
	}
}

原文效果图：

objectsToExclude 指的是啥、

https://github.com/boy20000/Mamt3D/blob/278af4419be5de27ac7111832d89e2f5d5084814/examples/analysis_viewshed.html

git上找了个可视域分析的demo