I am using interpolation for my sampledPositionProperty in order to smooth the angle of my aircraft. However, if my points are say
Pos A Time 1
Pos B Time 2
Pos C Time 3
Pos C Time 4
Pos C Time 5
Pos D Time 6
Then, the airplane goes all haywire at point C, not understanding that it should be waiting at that point. In other words, I need to find a way to smooth out the path between a set of points (interpolation) but if the starting point and ending point are the same, I need to have the interpolated point be the same. It would also be nice if the plane doesn't change orientation from the last known velocity-based orientation, but that is less important.
Below is an example code for the plane going haywire at the fixed point. In this example, the fixed point is after the half-circle and before the straight line back. Any advice or workaround would be greatly appreciated!
var viewer = new Cesium.Viewer('cesiumContainer', {
terrainProviderViewModels : , //Disable terrain changing
infoBox : false, //Disable InfoBox widget
selectionIndicator : false //Disable selection indicator
});
//Enable lighting based on sun/moon positions
viewer.scene.globe.enableLighting = true;
//Use STK World Terrain
viewer.terrainProvider = new Cesium.CesiumTerrainProvider({
url : ‘https://assets.agi.com/stk-terrain/world’,
requestWaterMask : true,
requestVertexNormals : true
});
//Enable depth testing so things behind the terrain disappear.
viewer.scene.globe.depthTestAgainstTerrain = true;
//Set the random number seed for consistent results.
Cesium.Math.setRandomNumberSeed(3);
//Set bounds of our simulation time
var start = Cesium.JulianDate.fromDate(new Date(2015, 2, 25, 16));
var stop = Cesium.JulianDate.addSeconds(start, 360, new Cesium.JulianDate());
//Make sure viewer is at the desired time.
viewer.clock.startTime = start.clone();
viewer.clock.stopTime = stop.clone();
viewer.clock.currentTime = start.clone();
viewer.clock.clockRange = Cesium.ClockRange.LOOP_STOP; //Loop at the end
viewer.clock.multiplier = 10;
//Set timeline to simulation bounds
viewer.timeline.zoomTo(start, stop);
//Generate a random circular pattern with varying heights.
function computeCirclularFlight(lon, lat, radius) {
var property = new Cesium.SampledPositionProperty();
var rnd=Cesium.Math.nextRandomNumber() ;
for (var i = 0; i <= 360; i += 45) {
var x = i;
if (i>180 && i<360){
x=180;
}
var radians = Cesium.Math.toRadians(x);
var time = Cesium.JulianDate.addSeconds(start, i, new Cesium.JulianDate());
var position = Cesium.Cartesian3.fromDegrees(lon + (radius * 1.5 * Math.cos(radians)), lat + (radius * Math.sin(radians)), rnd * 500 + 1750);
property.addSample(time, position);
console.log(position.x);
console.log(position.y);
console.log(position.z);
//Also create a point for each sample we generate.
viewer.entities.add({
position : position,
point : {
pixelSize : 8,
color : Cesium.Color.TRANSPARENT,
outlineColor : Cesium.Color.YELLOW,
outlineWidth : 3
}
});
}
return property;
}
//Compute the entity position property.
var position = computeCirclularFlight(-112.110693, 36.0994841, 0.03);
//Actually create the entity
var entity = viewer.entities.add({
//Set the entity availability to the same interval as the simulation time.
availability : new Cesium.TimeIntervalCollection([new Cesium.TimeInterval({
start : start,
stop : stop
})]),
//Use our computed positions
position : position,
//Automatically compute orientation based on position movement.
orientation : new Cesium.VelocityOrientationProperty(position),
//Load the Cesium plane model to represent the entity
model : {
uri : '../../SampleData/models/CesiumAir/Cesium_Air.gltf',
minimumPixelSize : 64
},
//Show the path as a pink line sampled in 1 second increments.
path : {
resolution : 1,
material : new Cesium.PolylineGlowMaterialProperty({
glowPower : 0.1,
color : Cesium.Color.YELLOW
}),
width : 10
}
});
//Add button to view the path from the top down
Sandcastle.addDefaultToolbarButton('View Top Down', function() {
viewer.trackedEntity = undefined;
viewer.zoomTo(viewer.entities, new Cesium.HeadingPitchRange(0, Cesium.Math.toRadians(-90)));
});
//Add button to view the path from the side
Sandcastle.addToolbarButton('View Side', function() {
viewer.trackedEntity = undefined;
viewer.zoomTo(viewer.entities, new Cesium.HeadingPitchRange(Cesium.Math.toRadians(-90), Cesium.Math.toRadians(-15), 7500));
});
//Add button to track the entity as it moves
Sandcastle.addToolbarButton('View Aircraft', function() {
viewer.trackedEntity = entity;
});
//Add a combo box for selecting each interpolation mode.
Sandcastle.addToolbarMenu([{
text : 'Interpolation: Linear Approximation',
onselect : function() {
entity.position.setInterpolationOptions({
interpolationDegree : 2,
interpolationAlgorithm : Cesium.LinearApproximation
});
}
}, {
text : 'Interpolation: Lagrange Polynomial Approximation',
onselect : function() {
entity.position.setInterpolationOptions({
interpolationDegree :2,
interpolationAlgorithm : Cesium.LagrangePolynomialApproximation
});
}
}, {
text : 'Interpolation: Hermite Polynomial Approximation',
onselect : function() {
entity.position.setInterpolationOptions({
interpolationDegree : 2,
interpolationAlgorithm : Cesium.HermitePolynomialApproximation
});
}
}], 'interpolationMenu');
