1   package org.orekit.estimation;
2   
3   import java.util.List;
4   
5   import org.hipparchus.geometry.euclidean.threed.Vector3D;
6   import org.hipparchus.util.FastMath;
7   import org.orekit.bodies.CelestialBody;
8   import org.orekit.bodies.GeodeticPoint;
9   import org.orekit.bodies.OneAxisEllipsoid;
10  import org.orekit.estimation.measurements.GroundStation;
11  import org.orekit.frames.TopocentricFrame;
12  import org.orekit.models.earth.displacement.StationDisplacement;
13  import org.orekit.orbits.CartesianOrbit;
14  import org.orekit.orbits.Orbit;
15  import org.orekit.orbits.PositionAngle;
16  import org.orekit.propagation.conversion.KeplerianPropagatorBuilder;
17  import org.orekit.time.TimeScale;
18  import org.orekit.time.UT1Scale;
19  import org.orekit.utils.IERSConventions;
20  import org.orekit.utils.PVCoordinates;
21  
22  public class KeplerianContext implements StationDataProvider {
23  
24      public IERSConventions                        conventions;
25      public OneAxisEllipsoid                       earth;
26      public CelestialBody                          sun;
27      public CelestialBody                          moon;
28      public TimeScale                              utc;
29      public UT1Scale                               ut1;
30      public Orbit                                  initialOrbit;
31      public StationDisplacement[]                  displacements;
32      public List<GroundStation>                    stations;
33  
34      public KeplerianPropagatorBuilder createBuilder(final PositionAngle angleType, final boolean perfectStart, final double dP) {
35  
36          final Orbit startOrbit;
37          if (perfectStart) {
38              // orbit estimation will start from a perfect orbit
39              startOrbit = initialOrbit;
40          } else {
41              // orbit estimation will start from a wrong point
42              final Vector3D initialPosition = initialOrbit.getPVCoordinates().getPosition();
43              final Vector3D initialVelocity = initialOrbit.getPVCoordinates().getVelocity();
44              final Vector3D wrongPosition   = initialPosition.add(new Vector3D(1000.0, 0, 0));
45              final Vector3D wrongVelocity   = initialVelocity.add(new Vector3D(0, 0, 0.01));
46              startOrbit                     = new CartesianOrbit(new PVCoordinates(wrongPosition, wrongVelocity),
47                                                                  initialOrbit.getFrame(),
48                                                                  initialOrbit.getDate(),
49                                                                  initialOrbit.getMu());
50          }
51  
52          // Initialize builder
53          final KeplerianPropagatorBuilder propagatorBuilder =
54                          new KeplerianPropagatorBuilder(startOrbit, angleType, dP);
55  
56          // Return
57          return propagatorBuilder;
58  
59      }
60  
61      GroundStation createStation(double latitudeInDegrees, double longitudeInDegrees,
62                                  double altitude, String name) {
63          final GeodeticPoint gp = new GeodeticPoint(FastMath.toRadians(latitudeInDegrees),
64                                                     FastMath.toRadians(longitudeInDegrees),
65                                                     altitude);
66          return new GroundStation(new TopocentricFrame(earth, gp, name),
67                                   ut1.getEOPHistory(), displacements);
68      }
69  
70      @Override
71      public List<GroundStation> getStations() {
72          return stations;
73      }
74  
75  }