前期卫星地面站创建已经说过，本次说一下卫星和地面站可见性时卫星名称和轨迹线变色问题。

1.创建卫星

// Get the current TLE for the given satellite identifier.
var tleList = TwoLineElementSetHelper.GetTles(m_satelliteIdentifier, JulianDate.Now);// Use the epoch of the first TLE, since the TLE may have been loaded from offline data.
m_epoch = tleList[0].Epoch;// Propagate the TLE and use that as the satellite's location point.
var locationPoint = new Sgp4Propagator(tleList).CreatePoint();
m_satellite = new Platform
{Name = "Satellite " + m_satelliteIdentifier,LocationPoint = locationPoint,// Orient the satellite using Vehicle Velocity Local Horizontal (VVLH) axes.OrientationAxes = new AxesVehicleVelocityLocalHorizontal(m_earth.FixedFrame, locationPoint),
};// Set the identifier for the satellite in the CZML document.
m_satellite.Extensions.Add(new IdentifierExtension(m_satelliteIdentifier));// Configure a glTF model for the satellite.
m_satellite.Extensions.Add(new ModelGraphicsExtension(new ModelGraphics
{// Link to a binary glTF file.Model = new CesiumResource(GetModelUri("satellite.glb"), CesiumResourceBehavior.LinkTo),// By default, Cesium plays all animations in the model simultaneously, which is not desirable.RunAnimations = false,
}));

2.创建地面站

// Define the location of the facility using cartographic coordinates.
var location = new Cartographic(Trig.DegreesToRadians(-75.596766667), Trig.DegreesToRadians(40.0388333333), 0.0);
var locationPoint = new PointCartographic(m_earth, location);
m_facility = new Platform
{Name = "AGI HQ",LocationPoint = locationPoint,// Orient the facility using East-North-Up (ENU) axes.OrientationAxes = new AxesEastNorthUp(m_earth, locationPoint),
};// Set the identifier for the facility in the CZML document. 
m_facility.Extensions.Add(new IdentifierExtension("AGI"));// Configure a glTF model for the facility.
m_facility.Extensions.Add(new ModelGraphicsExtension(new ModelGraphics
{// Link to a binary glTF file.Model = new CesiumResource(GetModelUri("facility.glb"), CesiumResourceBehavior.LinkTo),RunAnimations = false,HeightReference = CesiumHeightReference.ClampToGround,
}));// Configure label for AGI HQ.
m_facility.Extensions.Add(new LabelGraphicsExtension(new LabelGraphics
{Text = m_facility.Name,FillColor = Color.White,// Only show label when camera is far enough from the satellite,// to avoid visually clashing with the model.DistanceDisplayCondition = new Bounds(1000.0, double.MaxValue),HeightReference = CesiumHeightReference.ClampToGround,
}));

3.创建卫星和地面站关系

m_satelliteFacilityLink = new LinkInstantaneous(m_facility, m_satellite);// Set the identifier for the link in the CZML document. 
m_satelliteFacilityLink.Extensions.Add(new IdentifierExtension("SatelliteFacilityAccess"));// Specify how access should be constrained.  In this case, 
// access will only exist when no part of the earth is between AGI HQ and the satellite.
m_accessQuery = new CentralBodyObstructionConstraint(m_satelliteFacilityLink, m_earth);// Configure graphical display of the access link.
m_satelliteFacilityLink.Extensions.Add(new LinkGraphicsExtension(new LinkGraphics
{// Show the access link only when access is satisfied.Show = new AccessQueryCesiumProperty<bool>(m_accessQuery, true, false, false),Material = new SolidColorMaterialGraphics(Color.Yellow),
}));

因为随着可见性变色，需要在关系中获取到可见时间。

AccessEvaluator evaluator = m_accessQuery.GetEvaluator();// Compute the time intervals when the viewing location is able to see the satellite.
AccessQueryResult accessResult = evaluator.Evaluate(m_epoch, m_epoch.AddDays(1));
var accessIntervals = accessResult.SatisfactionIntervals;
var LabelResults = new TimeIntervalCollection<Color>();LabelResults =GetColorList(accessIntervals, m_epoch, false);
m_satellite.Extensions.Add(new LabelGraphicsExtension(new LabelGraphics
{Text = new ConstantCesiumProperty<string>(m_satellite.Name),Font= new ConstantCesiumProperty<string>("20px"),FillColor = LabelResults,}));var LineResults = new TimeIntervalCollection<Color>();
LineResults = GetColorList(accessIntervals, m_epoch, true);
m_satellite.Extensions.Add(new PathGraphicsExtension(new PathGraphics
{Material = new PolylineOutlineMaterialGraphics{Color = LineResults,OutlineWidth = new ConstantCesiumProperty<double>(1.0),OutlineColor = new ConstantCesiumProperty<Color>(Color.Black),},Width = 2,LeadTime = Duration.FromMinutes(44).TotalSeconds,TrailTime = Duration.FromMinutes(44).TotalSeconds,
}));

  public static TimeIntervalCollection<Color> GetColorList(TimeIntervalCollection accessIntervals, Define.Link struLink,bool isLine){var results = new TimeIntervalCollection<Color>();JulianDate tmp = new JulianDate();foreach (TimeInterval interval in accessIntervals){if (results.Count() == 0){results.Add(new TimeInterval<Color>(struLink.m_jBeginTime, interval.Start.ToGregorianDate().ToJulianDate(), Color.White, true, false));}if (tmp.ToString() != ""){results.Add(new TimeInterval<Color>(tmp, interval.Start.ToGregorianDate().ToJulianDate(), Color.White, true, false));}if(isLine){results.Add(new TimeInterval<Color>(interval.Start.ToGregorianDate().ToJulianDate(), interval.Stop.ToGregorianDate().ToJulianDate(), Color.Red, false, true));}else{results.Add(new TimeInterval<Color>(interval.Start.ToGregorianDate().ToJulianDate(), interval.Stop.ToGregorianDate().ToJulianDate(), Color.Green, false, true));}tmp = interval.Stop.ToGregorianDate().ToJulianDate();}return results;}

效果：

轨迹线和名称变色