/// <summary>
/// Load TLEs from a satellite database and create marker primitives for each satellite
/// </summary>
private void CreateSatellites(string fileName)
{
m_satellites.Clear();
JulianDate?epoch = null;
StkSatelliteDatabase db = new StkSatelliteDatabase(GetDataFilePath("SatelliteDatabase"), fileName);
foreach (StkSatelliteDatabaseEntry entry in db.GetEntries())
{
if (entry.TwoLineElementSet != null)
{
Sgp4Propagator propagator = new Sgp4Propagator(entry.TwoLineElementSet);
if (epoch == null)
{
epoch = propagator.InitialConditions.Epoch;
}
Duration epochDifference = epoch.Value - propagator.InitialConditions.Epoch;
if (epochDifference < Duration.FromDays(1))
{
m_satellites.Add(propagator.GetEvaluator(), entry.TwoLineElementSet.Epoch);
}
}
}
SetText(m_satellites.Count);
JulianDate time = epoch.Value.ToTimeStandard(TimeStandard.InternationalAtomicTime);
// Set epoch time
m_animation.Pause();
m_animation.StartTime = time;
m_animation.EndTime = time.AddDays(1.0);
m_animation.Time = time;
m_animation.PlayForward();
}
/// <summary>
/// Creates a new instance with the provided properties.
/// </summary>
public IridiumSatellite(string name, IEnumerable <TwoLineElementSet> tles, Font font, double targetFrequency)
{
var earth = CentralBodiesFacet.GetFromContext().Earth;
//Set the name and create the point from the TLE.
Name = name;
LocationPoint = new Sgp4Propagator(tles).CreatePoint();
OrientationAxes = new AxesVehicleVelocityLocalHorizontal(earth.InertialFrame, LocationPoint);
//Create a transceiver modeled after Iridium specs.
m_transceiver = new Transceiver
{
Name = Name + " Transceiver",
Modulation = new ModulationQpsk(),
OutputGain = 100.0,
OutputNoiseFactor = 1.2,
CarrierFrequency = targetFrequency,
Filter = new RectangularFilter
{
Frequency = targetFrequency,
UpperBandwidthLimit = 20.0e6,
LowerBandwidthLimit = -20.0e6
},
InputAntennaGainPattern = new GaussianGainPattern(1.0, 0.55, 0.001),
OutputAntennaGainPattern = new GaussianGainPattern(1.0, 0.55, 0.001)
};
m_transceiver.InputAntenna.LocationPoint = new PointFixedOffset(ReferenceFrame, new Cartesian(0, -1.0, 0));
m_transceiver.OutputAntenna.LocationPoint = new PointFixedOffset(ReferenceFrame, new Cartesian(0, +1.0, 0));
// setup Marker graphics for the satellites
var satelliteTexture = SceneManager.Textures.FromUri(Path.Combine(Application.StartupPath, "Data/Markers/smallsatellite.png"));
m_markerGraphicsExtension = new MarkerGraphicsExtension(new MarkerGraphics
{
Texture = new ConstantGraphicsParameter <Texture2D>(satelliteTexture),
DisplayParameters = new DisplayParameters
{
// hide marker when camera is closer than the below distance
MinimumDistance = new ConstantGraphicsParameter <double>(17500000.0)
}
});
Extensions.Add(m_markerGraphicsExtension);
// setup Model graphics for the satellites
var modelUri = new Uri(Path.Combine(Application.StartupPath, "Data/Models/iridium.mdl"));
m_modelGraphicsExtension = new ModelGraphicsExtension(new ModelGraphics
{
Uri = new ConstantGraphicsParameter <Uri>(modelUri),
Scale = new ConstantGraphicsParameter <double>(50000.0),
DisplayParameters = new DisplayParameters
{
// hide model when camera is further than the marker minimum distance above
MaximumDistance = m_markerGraphicsExtension.MarkerGraphics.DisplayParameters.MinimumDistance
}
});
Extensions.Add(m_modelGraphicsExtension);
// setup text graphics for the satellites
m_textGraphicsExtension = new TextGraphicsExtension(new TextGraphics
{
Color = new ConstantGraphicsParameter <Color>(Color.Red),
Font = new ConstantGraphicsParameter <Font>(font),
Outline = new ConstantGraphicsParameter <bool>(true),
OutlineColor = new ConstantGraphicsParameter <Color>(Color.Black),
Text = new ConstantGraphicsParameter <string>(Name),
Origin = new ConstantGraphicsParameter <Origin>(Origin.TopCenter),
PixelOffset = new ConstantGraphicsParameter <PointF>(new PointF(0, -satelliteTexture.Template.Height / 2))
});
if (TextureFilter2D.Supported(TextureWrap.ClampToEdge))
{
m_textGraphicsExtension.TextGraphics.TextureFilter = new ConstantGraphicsParameter <TextureFilter2D>(TextureFilter2D.NearestClampToEdge);
}
Extensions.Add(m_textGraphicsExtension);
}
/// <summary>
/// Create a Platform for the requested satellite using a TLE for position.
/// The satellite will be visually represented by a labeled glTF model,
/// the satellite's orbit will be shown, and vectors will be drawn for
/// the body axes of the satellite, plus a vector indicating the direction
/// of the sun.
/// </summary>
private void CreateSatellite()
{
// 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,
}));
// Configure a label for the satellite.
m_satellite.Extensions.Add(new LabelGraphicsExtension(new LabelGraphics
{
// Use the name of the satellite as the text of the label.
Text = m_satellite.Name,
// Change the color of the label after 12 hours. This demonstrates specifying that
// a value varies over time using intervals.
FillColor = new TimeIntervalCollection <Color>
{
// Green for the first half day...
new TimeInterval <Color>(JulianDate.MinValue, m_epoch.AddDays(0.5), Color.Green, true, false),
// Red thereafter.
new TimeInterval <Color>(m_epoch.AddDays(0.5), JulianDate.MaxValue, Color.Red, false, true),
},
// 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),
}));
// Configure graphical display of the orbital path of the satellite.
m_satellite.Extensions.Add(new PathGraphicsExtension(new PathGraphics
{
// Configure the visual appearance of the line.
Material = new PolylineOutlineMaterialGraphics
{
Color = Color.White,
OutlineWidth = 1.0,
OutlineColor = Color.Black,
},
Width = 2.0,
// Lead and Trail time indicate how much of the path to render.
LeadTime = Duration.FromMinutes(44.0).TotalSeconds,
TrailTime = Duration.FromMinutes(44.0).TotalSeconds,
}));
// Create vectors for the X, Y, and Z axes of the satellite.
m_satelliteXAxis = CreateAxesVector(m_satellite, CartesianElement.X, Color.Green, "SatelliteX");
m_satelliteYAxis = CreateAxesVector(m_satellite, CartesianElement.Y, Color.Red, "SatelliteY");
m_satelliteZAxis = CreateAxesVector(m_satellite, CartesianElement.Z, Color.Blue, "SatelliteZ");
// Create a vector from the satellite to the Sun.
// Compute the vector from the satellite's location to the Sun's center of mass.
var sunCenterOfMassPoint = CentralBodiesFacet.GetFromContext().Sun.CenterOfMassPoint;
var vectorSatelliteToSun = new VectorTrueDisplacement(m_satellite.LocationPoint, sunCenterOfMassPoint);
// Create the visual vector.
m_satelliteSunVector = new GraphicalVector
{
LocationPoint = m_satellite.LocationPoint,
Vector = vectorSatelliteToSun,
VectorGraphics = new VectorGraphics
{
Length = 5.0,
Color = Color.Yellow,
},
};
// Set the identifier for the vector in the CZML document.
m_satelliteSunVector.Extensions.Add(new IdentifierExtension("SunVector"));
// Orient the solar panels on the satellite model to point at the sun.
var satelliteYVector = m_satellite.OrientationAxes.GetVectorElement(CartesianElement.Y);
// allow only Z axis to rotate to follow sun vector. Constrain sun vector to Y, and satellite Y vector to X.
var constrainedAxes = new AxesAlignedConstrained(satelliteYVector, AxisIndicator.First, vectorSatelliteToSun, AxisIndicator.Second);
// Satellite axes are Vehicle Velocity Local Horizontal (VVLH) axes, where X is forward and Z is down,
// but Cesium model axes are Z forward, Y up. So, create an axes rotates to the Cesium model axes.
var offset = new UnitQuaternion(new ElementaryRotation(AxisIndicator.First, -Math.PI / 2)) *
new UnitQuaternion(new ElementaryRotation(AxisIndicator.Third, Math.PI / 2));
var cesiumModelAxes = new AxesFixedOffset(m_satellite.OrientationAxes, offset);
// The rotation will be from the Cesium model axes to the constrained axes.
var solarPanelRotationAxes = new AxesInAxes(constrainedAxes, cesiumModelAxes);
// Add a node transformation to rotate the SolarPanels node of the model.
m_satellite.Extensions.GetByType <ModelGraphicsExtension>().ModelGraphics.NodeTransformations = new Dictionary <string, NodeTransformationGraphics>
{
{
"SolarPanels", new NodeTransformationGraphics
{
Rotation = new AxesCesiumProperty(solarPanelRotationAxes)
}
}
};
}
