fr.cnes.sirius.patrius.bodies.mesh

Class FacetCelestialBody

java.lang.Object

fr.cnes.sirius.patrius.bodies.AbstractCelestialBody

fr.cnes.sirius.patrius.bodies.UserCelestialBody

fr.cnes.sirius.patrius.bodies.mesh.FacetCelestialBody

All Implemented Interfaces:

BodyShape, CelestialBody, GeometricBodyShape, PVCoordinatesProvider, Serializable

public class FacetCelestialBody
extends UserCelestialBody
implements GeometricBodyShape

Celestial body defined by a list of facets. A facet is a 3D triangle defined in the body frame.

This class offers an optimal storage under a Binary Space Partition Tree (BSP Tree). Each of the body facet (class Triangle) is linked to its neighbors. Each of the body vertex (class Vertex) is also linked to its neighboring triangles Triangle. Hence this class provides very efficient methods (O(log n)) for intersection computation, neighbors computation, etc.

This class inherits interfaces CelestialBody and GeometricBodyShape:

• As a GeometricBodyShape, this class can be used in conjunction with EclipseDetector and SensorModel.
• As a CelestialBody, this class can be used with any CelestialBody-related class (attitude laws, etc.).

Since:

4.6

Author:

Emmanuel Bignon

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
FacetCelestialBody(String name, PVCoordinatesProvider pvBody, double gm, IAUPole iauPole, MeshProvider meshLoader) Constructor.

Method Summary

Modifier and Type	Method and Description
double	distanceTo(Line line, Frame frame, AbsoluteDate date) Computes the distance to a line.
Frame	getBodyFrame() Get body frame related to body shape.
FieldData	getFieldData(SpacecraftState state, IFieldOfView fieldOfView, Vector3D lineOfSight) Returns the field data as FieldData for each state in provided list.
ExtendedOneAxisEllipsoid	getInnerSphere() Returns Inner reference sphere which is largest sphere strictly contained in mesh and centered around (0, 0, 0).
Intersection	getIntersection(Line line, Vector3D close, Frame frame, AbsoluteDate date) Get the intersection point with associated triangle of a line with the surface of the body in the body frame.
GeodeticPoint	getIntersectionPoint(Line line, Vector3D close, Frame frame, AbsoluteDate date) Get the intersection point of a line with the surface of the body.
Vector3D[]	getIntersectionPoints(Line line, Frame frame, AbsoluteDate date) Compute the intersection points with a line.
double	getLocalAltitude(double latitude, double longitude) Returns the altitude of body at point (latitude, longitude).
double	getLocalAltitude(Vector3D direction) Returns the altitude of body given provided direction in body frame.
double	getLocalRadius(Vector3D position, Frame frame, AbsoluteDate date, PVCoordinatesProvider occultedBody) Calculate the apparent radius.
double	getMaxNorm() Returns the distance from center to farthest vertex to center of body.
double	getMinNorm() Returns the distance from center to closest vertex to center of body.
List<Triangle>	getNeighbors(GeodeticPoint point, double maxDistance) Returns the neighbors of provided geodetic point whose center is closer than provided distance.
List<Triangle>	getNeighbors(GeodeticPoint point, int order) Returns the neighbor triangles of provided geodetic point which are closer or equal to provided order of "neighborhood".
List<Triangle>	getNeighbors(Triangle triangle, double maxDistance) Returns the neighbors of provided triangle whose center is closer than provided distance of provided triangle center.
List<Triangle>	getNeighbors(Triangle triangle, int order) Returns the neighbors of provided triangle whose distance in terms of triangle is closer or equal to provided order of "neighborhood".
List<Triangle>	getNeighbors(Vector3D pos, double maxDistance) Returns the neighbors of provided cartesian point whose center is closer than provided distance.
List<Triangle>	getNeighbors(Vector3D pos, int order) Returns the neighbor triangles of provided cartesian point which are closer or equal to provided order of "neighborhood".
List<Triangle>	getNeverEnlightenedTriangles(List<AbsoluteDate> dates, PVCoordinatesProvider sun) Returns the list of triangles never enlightened by the Sun at provided dates.
List<Triangle>	getNeverVisibleTriangles(List<SpacecraftState> states, IFieldOfView fieldOfView) Returns the list of triangles never visible from the satellite field of view during the whole ephemeris.
ExtendedOneAxisEllipsoid	getReferenceEllipsoid() Returns reference ellipsoid which is ellipsoid (a, f) which minimize distance to all vertices.
List<SurfacePointedData>	getSurfacePointedDataEphemeris(List<SpacecraftState> states, Vector3D lineOfSight, PVCoordinatesProvider sun, double pixelFOV) Returns the body surface pointed data as SurfacePointedData for each state in provided list.
Triangle[]	getTriangles() Returns the mesh under a list of triangles.
List<Triangle>	getVisibleAndEnlightenedTriangles(List<SpacecraftState> states, PVCoordinatesProvider sun, IFieldOfView fieldOfView) Returns the list of triangles enlightened (by the Sun) and visible at least once during the whole ephemeris from the satellite field of view.
boolean	isInEclipse(AbsoluteDate date, Vector3D position, Frame frame, PVCoordinatesProvider sun) Returns true if provided position in provided frame at provided date in in eclipse or not.
Vector3D	transform(GeodeticPoint point) Transform a surface-relative point to a cartesian point.
GeodeticPoint	transform(Vector3D point, Frame frame, AbsoluteDate date) Transform a cartesian point to a surface-relative point.

Methods inherited from class fr.cnes.sirius.patrius.bodies.UserCelestialBody

getPVCoordinates, toString

Methods inherited from class fr.cnes.sirius.patrius.bodies.AbstractCelestialBody

getBodyOrientedFrame, getGM, getInertiallyOrientedFrame, getName

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface fr.cnes.sirius.patrius.bodies.GeometricBodyShape

getName

Methods inherited from interface fr.cnes.sirius.patrius.orbits.pvcoordinates.PVCoordinatesProvider

getPVCoordinates

Constructor Detail

FacetCelestialBody

public FacetCelestialBody(String name,
                          PVCoordinatesProvider pvBody,
                          double gm,
                          IAUPole iauPole,
                          MeshProvider meshLoader)
                   throws PatriusException

Constructor.

Parameters:

name - body name

pvBody - Body PV coordinates

gm - body gravitational parameter

iauPole - IAU pole model

meshLoader - mesh loader

Throws:

PatriusException - thrown if loading failed

Method Detail

getTriangles

public Triangle[] getTriangles()

Returns the mesh under a list of triangles. The triangles are not sorted in any particular way.

Returns:

the mesh under a list of triangles

getBodyFrame

public final Frame getBodyFrame()

Get body frame related to body shape.

Specified by:

getBodyFrame in interface BodyShape

Returns:

body frame related to body shape

getIntersectionPoint

public GeodeticPoint getIntersectionPoint(Line line,
                                          Vector3D close,
                                          Frame frame,
                                          AbsoluteDate date)
                                   throws PatriusException

Get the intersection point of a line with the surface of the body.

A line may have several intersection points with a closed surface (we consider the one point case as a degenerated two points case). The close parameter is used to select which of these points should be returned. The selected point is the one that is closest to the close point.

Specified by:

getIntersectionPoint in interface BodyShape

Parameters:

line - test line (may intersect the body or not)

close - point used for intersections selection

frame - frame in which line is expressed

date - date of the line in given frame

Returns:

intersection point at altitude zero or null if the line does not intersect the surface

Throws:

PatriusException - if line cannot be converted to body frame

getIntersectionPoints

public Vector3D[] getIntersectionPoints(Line line,
                                        Frame frame,
                                        AbsoluteDate date)
                                 throws PatriusException

Compute the intersection points with a line.

Specified by:

getIntersectionPoints in interface GeometricBodyShape

Parameters:

line - the line

frame - in which line is expressed

date - date of the line in given frame

Returns:

the intersection points if they exist. If no intersection is found, the dimension is zero

Throws:

PatriusException - if line cannot be converted to body frame

getIntersection

public Intersection getIntersection(Line line,
                                    Vector3D close,
                                    Frame frame,
                                    AbsoluteDate date)
                             throws PatriusException

Get the intersection point with associated triangle of a line with the surface of the body in the body frame.

A line may have several intersection points with a closed surface (we consider the one point case as a degenerated two points case). The close parameter is used to select which of these points should be returned. The selected point is the one that is closest to the close point.

Warning: does not take into account sight direction. The line is considered to be infinite.

Parameters:

line - test line (may intersect the body or not)

close - point used for intersections selection in frame

frame - frame in which line is expressed

date - date of the line in given frame

Returns:

or null if the line does not intersect the surface

Throws:

PatriusException - if line cannot be converted to body frame

transform

public GeodeticPoint transform(Vector3D point,
                               Frame frame,
                               AbsoluteDate date)
                        throws PatriusException

Transform a cartesian point to a surface-relative point.

Warning: this method considers the body as the inner sphere (which is largest sphere strictly contained in the mesh.

Specified by:

transform in interface BodyShape

Parameters:

point - cartesian point

frame - frame in which cartesian point is expressed

date - date of the computation (used for frames conversions)

Returns:

point at the same location but as a surface-relative point

Throws:

PatriusException - if point cannot be converted to body frame

transform

public Vector3D transform(GeodeticPoint point)

Transform a surface-relative point to a cartesian point.

Warning: this method considers the body as the inner sphere (which is largest sphere strictly contained in the mesh.

Specified by:

transform in interface BodyShape

Parameters:

point - surface-relative point

Returns:

point at the same location but as a cartesian point

getLocalAltitude

public double getLocalAltitude(double latitude,
                               double longitude)
                        throws PatriusException

Returns the altitude of body at point (latitude, longitude). The returned altitude is the altitude of the point belonging to the mesh with provided latitude, longitude.

Altitude is relative to the inner sphere to the body (which is the largest sphere strictly inside the mesh).

Parameters:

latitude - latitude

longitude - longitude

Returns:

the altitude of body at point (latitude, longitude)

Throws:

PatriusException - thrown if failed to compute intersection

getLocalAltitude

public double getLocalAltitude(Vector3D direction)
                        throws PatriusException

Returns the altitude of body given provided direction in body frame.

Altitude is relative to the inner sphere to the body (which is the largest sphere strictly inside the mesh).

Parameters:

direction - direction in body frame

Returns:

altitude of body given provided direction in body frame

Throws:

PatriusException - thrown if failed to compute intersection

distanceTo

public double distanceTo(Line line,
                         Frame frame,
                         AbsoluteDate date)
                  throws PatriusException

Computes the distance to a line.

Warning: in case of strongly not convex bodies, this methods may not return exact minimal distance.

Specified by:

distanceTo in interface GeometricBodyShape

Parameters:

line - the line

frame - in which line is expressed

date - date of the line in given frame

Returns:

the shortest distance between the the line and the shape

Throws:

PatriusException - if line cannot be converted to body frame

getLocalRadius

public double getLocalRadius(Vector3D position,
                             Frame frame,
                             AbsoluteDate date,
                             PVCoordinatesProvider occultedBody)
                      throws PatriusException

Calculate the apparent radius.

Warning: this method considers the body as the closest one axis ellipsoid to the body (which is the one minimizing the distance to each vertex).

Specified by:

getLocalRadius in interface GeometricBodyShape

Parameters:

position - spacecraft position

frame - frame in which position is expressed

date - date of position

occultedBody - body occulted by this

Returns:

apparent radius

Throws:

PatriusException - if PVCoordinatesProvider computation fails

getNeighbors

public List<Triangle> getNeighbors(Triangle triangle,
                                   double maxDistance)

Returns the neighbors of provided triangle whose center is closer than provided distance of provided triangle center.

Provided triangle is included in the list of neighbors.

Beware not to confuse this method with getNeighbors(Triangle, int)

Parameters:

triangle - a triangle

maxDistance - max distance

Returns:

the neighbors of provided triangle whose center is closer than provided distance of provided triangle center

getNeighbors

public List<Triangle> getNeighbors(Triangle triangle,
                                   int order)

Returns the neighbors of provided triangle whose distance in terms of triangle is closer or equal to provided order of "neighborhood". For example:

• Order 0 returns provided triangle
• Order 1 returns provided triangle and the immediate neighbors of provided triangle
• Order 2 returns provided triangle, the immediate neighbors of provided triangle and also their own immediate neighbors

Beware not to confuse this method with getNeighbors(Triangle, double)

Parameters:

triangle - a triangle

order - order of "neighborhood"

Returns:

the neighbors of provided triangle whose distance in terms of triangle is closer or equal to provided order of "neighborhood"

getNeighbors

public List<Triangle> getNeighbors(GeodeticPoint point,
                                   double maxDistance)
                            throws PatriusException

Returns the neighbors of provided geodetic point whose center is closer than provided distance.

Parameters:

point - a geodetic point

maxDistance - max distance

Returns:

the neighbors of provided geodetic point whose center is closer than provided distance

Throws:

PatriusException - thrown if computation failed (should not happen)

getNeighbors

public List<Triangle> getNeighbors(GeodeticPoint point,
                                   int order)
                            throws PatriusException

Returns the neighbor triangles of provided geodetic point which are closer or equal to provided order of "neighborhood". For example:

• Order 0 returns closest triangle
• Order 1 returns closest triangle and the immediate neighbors of closest triangle
• Order 2 returns closest triangle, the immediate neighbors of closest triangle and also their own immediate neighbors

Beware not to confuse this method with getNeighbors(GeodeticPoint, double)

Parameters:

point - a geodetic point

order - order of "neighborhood"

Returns:

the neighbor triangles of provided geodetic point which are closer or equal to provided order of "neighborhood"

Throws:

PatriusException - thrown if computation failed (should not happen)

getNeighbors

public List<Triangle> getNeighbors(Vector3D pos,
                                   double maxDistance)
                            throws PatriusException

Returns the neighbors of provided cartesian point whose center is closer than provided distance.

Parameters:

pos - a point in body frame

maxDistance - max distance

Returns:

the neighbors of provided cartesian point whose center is closer than provided distance

Throws:

PatriusException - thrown if computation failed (should not happen)

getNeighbors

public List<Triangle> getNeighbors(Vector3D pos,
                                   int order)
                            throws PatriusException

Returns the neighbor triangles of provided cartesian point which are closer or equal to provided order of "neighborhood". For example:

• Order 0 returns closest triangle
• Order 1 returns closest triangle and the immediate neighbors of closest triangle
• Order 2 returns closest triangle, the immediate neighbors of closest triangle and also their own immediate neighbors

Beware not to confuse this method with getNeighbors(Vector3D, double)

Parameters:

pos - a point in body frame

order - order of "neighborhood"

Returns:

the neighbor triangles of provided cartesian point which are closer or equal to provided order of "neighborhood"

Throws:

PatriusException - thrown if computation failed (should not happen)

getSurfacePointedDataEphemeris

public List<SurfacePointedData> getSurfacePointedDataEphemeris(List<SpacecraftState> states,
                                                               Vector3D lineOfSight,
                                                               PVCoordinatesProvider sun,
                                                               double pixelFOV)
                                                        throws PatriusException

Returns the body surface pointed data as SurfacePointedData for each state in provided list.

Parameters:

states - list of spacecraft states

lineOfSight - line of sight in spacecraft frame

sun - Sun body

pixelFOV - aperture of field of view for one pixel

Returns:

list of SurfacePointedData, one per provided date

Throws:

PatriusException - thrown if state position could not be retrieved in body frame or if intersection is null or Sun frame conversion failed

getFieldData

public FieldData getFieldData(SpacecraftState state,
                              IFieldOfView fieldOfView,
                              Vector3D lineOfSight)
                       throws PatriusException

Returns the field data as FieldData for each state in provided list.

Parameters:

state - spacecraft state

fieldOfView - sensor field of view

lineOfSight - optional parameter in order to indicate field of view main line of sight in spacecraft frame. If provided, this parameter may fasten algorithm by several order of magnitudes (O(log n) vs O(n)). Be careful, in this case, strongly not convex bodies may lead to missing some triangles.

Returns:

FieldData for corresponding state

Throws:

PatriusException - thrown if state position could not be retrieved in body frame

isInEclipse

public boolean isInEclipse(AbsoluteDate date,
                           Vector3D position,
                           Frame frame,
                           PVCoordinatesProvider sun)
                    throws PatriusException

Returns true if provided position in provided frame at provided date in in eclipse or not.

Computed eclipse status is exact and takes into account full body shape. This methods cannot however be used in conjunction with EclipseDetector since they use a different framework.

Parameters:

date - date

position - position

frame - frame in which position is expressed

sun - Sun body

Returns:

true if provided position in provided frame at provided date in in eclipse or not

Throws:

PatriusException - thrown if failed to retrieve Sun position of intersection points with body

getNeverVisibleTriangles

public List<Triangle> getNeverVisibleTriangles(List<SpacecraftState> states,
                                               IFieldOfView fieldOfView)
                                        throws PatriusException

Returns the list of triangles never visible from the satellite field of view during the whole ephemeris. A visible triangle must be properly oriented, in the field of view and not masked by any other triangle.

Parameters:

states - list of spacecraft states

fieldOfView - field of view

Returns:

list of Triangle never visible from the satellite field of view during the whole ephemeris

Throws:

PatriusException - thrown if state position could not be retrieved in body frame

getNeverEnlightenedTriangles

public List<Triangle> getNeverEnlightenedTriangles(List<AbsoluteDate> dates,
                                                   PVCoordinatesProvider sun)
                                            throws PatriusException

Returns the list of triangles never enlightened by the Sun at provided dates. An enlightened triangle must be properly oriented toward the Sun and not masked by any other triangle.

Parameters:

dates - list of dates

sun - Sun body

Returns:

list of Triangle never enlightened by the Sun

Throws:

PatriusException - thrown if state position could not be retrieved in body frame

getVisibleAndEnlightenedTriangles

public List<Triangle> getVisibleAndEnlightenedTriangles(List<SpacecraftState> states,
                                                        PVCoordinatesProvider sun,
                                                        IFieldOfView fieldOfView)
                                                 throws PatriusException

Returns the list of triangles enlightened (by the Sun) and visible at least once during the whole ephemeris from the satellite field of view. A visible triangle must be properly oriented, in the field of view and not masked by any other triangle. An enlightened triangle must be properly oriented toward the Sun and not masked by any other triangle.

Parameters:

states - list of spacecraft states

sun - sun

fieldOfView - field of view

Returns:

list of Triangle enlightened and visible at least once from the satellite field of view

Throws:

PatriusException - thrown if state position could not be retrieved in body frame

getReferenceEllipsoid

public ExtendedOneAxisEllipsoid getReferenceEllipsoid()

Returns reference ellipsoid which is ellipsoid (a, f) which minimize distance to all vertices.

Returns:

reference ellipsoid

getInnerSphere

public ExtendedOneAxisEllipsoid getInnerSphere()

Returns Inner reference sphere which is largest sphere strictly contained in mesh and centered around (0, 0, 0).

Returns:

inner sphere

getMinNorm

public double getMinNorm()

Returns the distance from center to closest vertex to center of body.

Returns:

the distance from center to closest vertex to center of body

getMaxNorm

public double getMaxNorm()

Returns the distance from center to farthest vertex to center of body.

Returns:

the distance from center to farthest vertex to center of body