How to obtain the coordinates of the aircraft passing through both ends of the radar

First, let's talk about the general implementation steps ：

1. Create a radar scanned entity and define the route of the aircraft ;
2. Use the interface of intervisibility analysis to find the position coordinates of the aircraft entering and exiting the radar detection range ;
3. Use coordinates to build line entities , The radar range is red , Green outside the range .

1. Create a radar scanned entity and define the route of the aircraft

First, create a radar scanning entity , Add radar entities by adding entities .
The main codes are as follows :

let sensorEntity = viewer.entities.add({
    position: Cesium.Cartesian3.fromDegrees(116.45093826887725, 39.90558654617389, 14.3030),
    rectangularSensor: new Cesium.RectangularSensorGraphics({
        radius: new Cesium.CallbackProperty(function () {
            return +self.radius;
        }, false),
        slice: 120,// Degree of segmentation 
        xHalfAngle: new Cesium.CallbackProperty(function () {
            return Cesium.Math.toRadians(self.xHalfAngle);
        }, false),// Angle between left and right 
        yHalfAngle: new Cesium.CallbackProperty(function () {
            return Cesium.Math.toRadians(self.yHalfAngle);
        }, false),// Angle between top and bottom 
        lineColor: new Cesium.CallbackProperty(function () {
            return Cesium.Color.fromCssColorString(self.lineColor);
        }, false),// Line color 
        material: new Cesium.Color(0.0, 1.0, 1.0, 1),// Uniform material 
        showScanPlane: new Cesium.CallbackProperty(function () {
            return self.scanPlane;
        }, false),// Display scanning surface 
        scanPlaneColor: new Cesium.CallbackProperty(function () {
            return Cesium.Color.fromCssColorString(self.scanPlaneColor);
        }, false),// Scanning surface color 
        scanPlaneMode: new Cesium.CallbackProperty(function () {
            return self.scanPlaneMode ? 'vertical' : 'horizontal';
        }, false),// Vertical scan mode 
        scanPlaneRate: new Cesium.CallbackProperty(function () {
            return self.scanPlaneRate;
        }, false),// Scanning rate 
        showIntersection: true,// Whether to display the scanning line with the earth 
        showThroughEllipsoid: false// Whether to cross the Earth shows 
    })
});

Then create an aircraft flight path , Let the plane fly along the line . It uses the clock function to make the aircraft fly along the line .
Main code ：

//  The plane flew along the line 
var startTime = Cesium.JulianDate.fromDate(new Date(2019, 2, 25, 16));
var startPosition = Cesium.Cartesian3.fromDegrees(116.47326309033961, 39.90512322998635, 600);
var endTime = Cesium.JulianDate.addSeconds(startTime, 1000, new Cesium.JulianDate());
var endPosition = Cesium.Cartesian3.fromDegrees(116.4189181104128, 39.903026132659456, 600);
viewer.clock.startTime = startTime.clone();
viewer.clock.stopTime = endTime.clone();
viewer.clock.currentTime = startTime.clone();
viewer.clock.clockRange = Cesium.ClockRange.LOOP_STOP; //Loop at the end
viewer.clock.multiplier = 10;
viewer.timeline.zoomTo(startTime, endTime);
var carPositionProperty = new Cesium.SampledPositionProperty();
carPositionProperty.addSample(startTime, startPosition);
carPositionProperty.addSample(endTime, endPosition);
var carPosition = carPositionProperty.getValue(viewer.clock.currentTime);
var heading = Cesium.Math.toRadians(-3);
var pitch = 0;
var roll = 0;
var hpr = new Cesium.HeadingPitchRoll(heading, pitch, roll);
var orientation = Cesium.Transforms.headingPitchRollQuaternion(carPosition, hpr);
var carModel = viewer.entities.add({
    name: "gltf",
    position: new Cesium.CallbackProperty(function () {
        return carPosition;
    }, false),
    orientation: orientation,
    model: {
        uri: "./SampleData/gltf/ The airliner model / The airliner model .gltf",
        scale: 60
    },
    viewFrom: new Cesium.Cartesian3(35, 70, 30)
});
viewer.clock.onTick.addEventListener(function () {
    var currentTime = Cesium.JulianDate.clone(viewer.clock.currentTime);
    carPosition = carPositionProperty.getValue(currentTime);
});

2. Use the interface of intervisibility analysis to find the position coordinates of the aircraft entering and exiting the radar detection range

Use intervisibility analysis to analyze from the takeoff point to the end point to obtain the coordinates of the first obstacle point close to the takeoff point ; Then, the intervisibility analysis is carried out in turn to obtain the coordinates of the second obstacle point away from the takeoff point ：
Main code ：

//  Coordinates of aircraft take-off end position : 
takeOffposition = [116.47326309033961, 39.90512322998635, 560]
finishposition = [116.4189181104128, 39.903026132659456, 560]
setTimeout(function () {
    //  Intervisibility analysis to judge the point position .
    sightline.build();
    sightline.lineWidth = 3
    // Set observation point 
    sightline.viewPosition = takeOffposition;
    //  Set the target point 
    var flag = sightline.addTargetPoint({
        position: finishposition,
        name: "point0"
    });
}, 200)
//  The method of obtaining the obstacle points delays the operation , Because intervisibility analysis takes time 
setTimeout(function () {
    sightline.getBarrierPoint("point0", function (e) {
        positions.fisrtObstacle = e.position
    })
    //  Clear the first intervisibility analysis result .
    sightline.removeAllTargetPoint();
    sightline.viewPosition = finishposition;
    var flag1 = sightline.addTargetPoint({
        position: takeOffposition,
        name: "point1"
    });
}, 300)
setTimeout(function () {
    sightline.getBarrierPoint("point1", function (e) {
        positions.secondObstacle = e.position
    })
    sightline.removeAllTargetPoint();
}, 380)

3. Use coordinates to build line entities , The radar range is red , Green outside the range .

This is relatively simple and directly attached with code ：

//  End position to the second entity out of radar range 
viewer.entities.add({
    id: "test1",
    polyline: {
        positions: Cesium.Cartesian3.fromDegreesArrayHeights([positions.secondObstacle.longitude * (180 / Math.PI), positions.secondObstacle.latitude * (180 / Math.PI), positions.secondObstacle.height, finishposition[0], finishposition[1], finishposition[2]]),
        width: 4.0,
        material: Cesium.Color.GREEN.withAlpha(0.9),
        depthFailMaterial: Cesium.Color.GREEN.withAlpha(0.9)
    }
});
//  Start position to enter the radar range entity 
viewer.entities.add({
    id: "test2",
    polyline: {
        positions: Cesium.Cartesian3.fromDegreesArrayHeights([positions.fisrtObstacle.longitude * (180 / Math.PI), positions.fisrtObstacle.latitude * (180 / Math.PI), positions.fisrtObstacle.height, takeOffposition[0], takeOffposition[1], takeOffposition[2]]),
        width: 4.0,
        material: Cesium.Color.GREEN.withAlpha(0.9),
        depthFailMaterial: Cesium.Color.GREEN.withAlpha(0.9)
    }
});
//  Construct a line entity found between two points 
viewer.entities.add({
    id: "test3",
    polyline: {
        positions: Cesium.Cartesian3.fromDegreesArrayHeights([positions.secondObstacle.longitude * (180 / Math.PI), positions.secondObstacle.latitude * (180 / Math.PI), positions.secondObstacle.height, positions.fisrtObstacle.longitude * (180 / Math.PI), positions.fisrtObstacle.latitude * (180 / Math.PI), positions.fisrtObstacle.height]),
        width: 4.0,
        material: Cesium.Color.RED.withAlpha(0.9),
        depthFailMaterial: Cesium.Color.RED.withAlpha(0.9)
    }
});

The end result is as follows :