Cesium之【空间面积】测量 - 好文

空间面积测量对象是平面，考虑到了取点的高度；地表面积测量的是球体（地球）曲面

//****************************测量空间面积************************************************//
var measureAreaSpace = function (viewer, handler){ handler = new
Cesium.ScreenSpaceEventHandler(viewer.scene._imageryLayerCollection); var
positions = []; var tempPoints = []; var polygon = null; var tooltip =
document.getElementById("toolTip"); var cartesian = null; var
floatingPoint;//浮动点 tooltip.style.display = "block";
handler.setInputAction(function(movement){ tooltip.style.left =
movement.endPosition.x + 3 + "px"; tooltip.style.top = movement.endPosition.y -
25 + "px"; tooltip.innerHTML ='<p>单击开始，右击结束</p>'; cartesian =
viewer.scene.pickPosition(movement.endPosition); //cartesian =
viewer.scene.camera.pickEllipsoid(movement.endPosition,
viewer.scene.globe.ellipsoid); if(positions.length >= 2){ if
(!Cesium.defined(polygon)) { polygon = new PolygonPrimitive(positions); }else{
positions.pop(); // cartesian.y += (1 + Math.random());
positions.push(cartesian); } // tooltip.innerHTML='<p>'+distance+'米</p>'; }
},Cesium.ScreenSpaceEventType.MOUSE_MOVE);
handler.setInputAction(function(movement){ tooltip.style.display = "none";
cartesian = viewer.scene.pickPosition(movement.position); // cartesian =
viewer.scene.camera.pickEllipsoid(movement.position,
viewer.scene.globe.ellipsoid); if(positions.length == 0) {
positions.push(cartesian.clone()); } //positions.pop();
positions.push(cartesian); //在三维场景中添加点 var cartographic =
Cesium.Cartographic.fromCartesian(positions[positions.length - 1]); var
longitudeString = Cesium.Math.toDegrees(cartographic.longitude); var
latitudeString = Cesium.Math.toDegrees(cartographic.latitude); var heightString
= cartographic.height; tempPoints.push({ lon: longitudeString, lat:
latitudeString ,hei:heightString}); floatingPoint = viewer.entities.add({ name
: '多边形面积', position : positions[positions.length - 1], point : { pixelSize : 5,
color : Cesium.Color.RED, outlineColor : Cesium.Color.WHITE, outlineWidth : 2,
heightReference:Cesium.HeightReference.none } });
},Cesium.ScreenSpaceEventType.LEFT_CLICK);
handler.setInputAction(function(movement){ handler.destroy(); positions.pop();
//tempPoints.pop(); viewer_g.entities.remove(floatingPoint);
tooltip.style.display = "none"; //在三维场景中添加点 // var cartographic =
Cesium.Cartographic.fromCartesian(positions[positions.length - 1]); // var
longitudeString = Cesium.Math.toDegrees(cartographic.longitude); // var
latitudeString = Cesium.Math.toDegrees(cartographic.latitude); // var
heightString = cartographic.height; // tempPoints.push({ lon: longitudeString,
lat: latitudeString ,hei:heightString}); var textArea = getArea(tempPoints) +
"平方公里"; viewer.entities.add({ name : '多边形面积', position :
positions[positions.length - 1], // point : { // pixelSize : 5, // color :
Cesium.Color.RED, // outlineColor : Cesium.Color.WHITE, // outlineWidth : 2, //
heightReference:Cesium.HeightReference.CLAMP_TO_GROUND // }, label : { text :
textArea, font : '18px sans-serif', fillColor : Cesium.Color.GOLD, style:
Cesium.LabelStyle.FILL_AND_OUTLINE, outlineWidth : 2, verticalOrigin :
Cesium.VerticalOrigin.BOTTOM, pixelOffset : new Cesium.Cartesian2(20, -40) }
}); }, Cesium.ScreenSpaceEventType.LEFT_DOUBLE_CLICK ); var radiansPerDegree =
Math.PI / 180.0;//角度转化为弧度(rad) var degreesPerRadian = 180.0 / Math.PI;//弧度转化为角度
//计算多边形面积 function getArea(points) { var res = 0; //拆分三角曲面 for (var i = 0; i <
points.length - 2; i++) { var j = (i + 1) % points.length; var k = (i + 2) %
points.length; var totalAngle = Angle(points[i], points[j], points[k]); var
dis_temp1 = distance(positions[j], positions[0]); var dis_temp2 =
distance(positions[k], positions[0]); res += dis_temp1 * dis_temp2 *
Math.sin(totalAngle) / 2; // console.log(res); } return Math.abs((res /
1000000.0).toFixed(4)); } /*角度*/ function Angle(p1, p2, p3) { var bearing21 =
Bearing(p2, p1); var bearing23 = Bearing(p2, p3); var angle = bearing21 -
bearing23; if (angle < 0) { angle += 360; } return angle; } /*方向*/ function
Bearing(from, to) { var lat1 = from.lat * radiansPerDegree; var lon1 = from.lon
* radiansPerDegree; var lat2 = to.lat * radiansPerDegree; var lon2 = to.lon *
radiansPerDegree; var angle = -Math.atan2(Math.sin(lon1 - lon2) *
Math.cos(lat2), Math.cos(lat1) * Math.sin(lat2) - Math.sin(lat1) *
Math.cos(lat2) * Math.cos(lon1 - lon2)); if (angle < 0) { angle += Math.PI *
2.0; } angle = angle * degreesPerRadian;//角度 return angle; } var
PolygonPrimitive = (function(){ function _(positions){ this.options = {
name:'多边形', polygon : { hierarchy : [], perPositionHeight : true, material :
Cesium.Color.GREEN.withAlpha(0.5) } }; this.hierarchy = positions;
this._init(); } _.prototype._init = function(){ var _self = this; var _update =
function(){ return _self.hierarchy; }; //实时更新polygon.hierarchy
this.options.polygon.hierarchy = new Cesium.CallbackProperty(_update,false);
viewer.entities.add(this.options); }; return _; })(); function
distance(point1,point2){ var point1cartographic =
Cesium.Cartographic.fromCartesian(point1); var point2cartographic =
Cesium.Cartographic.fromCartesian(point2); /**根据经纬度计算出距离**/ var geodesic = new
Cesium.EllipsoidGeodesic(); geodesic.setEndPoints(point1cartographic,
point2cartographic); var s = geodesic.surfaceDistance;
//console.log(Math.sqrt(Math.pow(distance, 2) + Math.pow(endheight, 2)));
//返回两点之间的距离 s = Math.sqrt(Math.pow(s, 2) + Math.pow(point2cartographic.height -
point1cartographic.height, 2)); return s; } };

参考： https://www.cnblogs.com/xiexinxinlove/p/3708147.html
<https://www.cnblogs.com/xiexinxinlove/p/3708147.html>

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