Rigid Body

Attributes Summary

`RigidBody.scale`	Scale of the body (`float`)
`RigidBody.position`	Position of the body (`numpy.ndarray` of shape `(3,)`)
`RigidBody.rotation`	Rotation of the body (`numpy.ndarray` of shape `(3,3)`)
`RigidBody.name`	NAIF name or ID code for the body (`str`)
`RigidBody.frame`	NAIF reference frame name for the body (`str`)
`RigidBody.origin`	NAIF name or ID code for the reference frame origin (`str`)
`RigidBody.ref`	NAIF reference frame name (`str`)
`RigidBody.abcorr`	Aberration correction flag (`str`)

Methods Summary

`RigidBody.set_scale`	Set a new `scale`
`RigidBody.set_position`	Set a new `position`
`RigidBody.set_rotation`	Set a new `rotation`
`RigidBody.set_pose`	Set both a new `position` and `rotation`
`RigidBody.spice_position`	Set new position for a given ephemeris time using SPICE
`RigidBody.spice_rotation`	Set new rotation for a given ephemeris time using SPICE
`RigidBody.spice_pose`	Set both a new position and rotation for a given ephemeris time using SPICE

class crt.RigidBody(position=array([0., 0., 0.]), rotation=array([[1., 0., 0.], [0., 1., 0.], [0., 0., 1.]]), scale=1, name=None, frame=None, origin='SSB', ref='J2000', abcorr='NONE')[source]

The RigidBody class is the superclass to Entity as well as all Camera and Light classes. It provides methods for adjusting the pose (position and orientation) as well as scale of a body. Additionally, it provides a SPICE interface allowing for NAIF ephemerides to be used to control the pose of a body.

Parameters

position (ArrayLike, optional) – Position of the body
Default: np.zeros(3)
rotation (ArrayLike, optional) – Rotation (orientation) of the body as a 3-by-3 rotation matrix that must obey both \(R^T = R^{-1}\) and \(\det(R)=1\)
Default: np.eye(3)
scale (Union[float, int], optional) – Scale of the body
Default: 1
name (Union[str, None], optional) – NAIF name or ID code of body
Default: None
frame (Union[str, None], optional) – NAIF reference frame name of body
Default: None
origin (Union[str, None], optional) – NAIF name or ID code of reference frame origin
Default: "SSB"
ref (Union[str, None], optional) – NAIF reference frame name of reference frame
Default: "J2000"
abcorr (Union[str, None], optional) – Aberration correction flag
Default: "NONE"

scale

Scale of the body (float)

This attribute is used by the subclass Entity and describes how the Entity geometry is scaled. It can be modified directly using set_scale().

position

Position of the body (numpy.ndarray of shape (3,))

This attribute is used by the subclass Entity, as well as all Camera and Light classes. It describes how the body is translated in space. It can be modified directly using either set_position() or set_pose(). Alternatively, it can be modified using spice_position() which uses predefined SPICE ephemerides to calculate a position for a given ephemeris time.

rotation

Rotation of the body (numpy.ndarray of shape (3,3))

This attribute is used by the subclasses Entity, as well as all Camera and Light classes. It describes how the body is translated in space. It can be modified directly using either set_rotation() or set_pose(). Alternatively, it can be modified using spice_rotation() which uses predefined SPICE ephemerides to calculate a rotation for a given ephemeris time.

name

NAIF name or ID code for the body (str)

This attribute can be used by the subclasses Entity, as well as all Camera and Light classes. It is used by the SPICE utility, spiceypy.spkpos(), as the name for the celestial body whose position will be used as the position of the body. This corresponds to the targ argument to spiceypy.spkpos(). Please refer to the spkpos documentation for more information.

frame

NAIF reference frame name for the body (str)

This attribute can be used by the subclasses Entity, as well as all Camera and Light classes. It is used by the SPICE utility, spiceypy.pxform(), as the name for the reference frame whose orientation will be used as the rotation of the body. This corresponds to the to argument to spiceypy.pxform(). Please refer to the pxform documentation for more information.

origin

NAIF name or ID code for the reference frame origin (str)

This attribute can be used by the subclasses Entity, as well as all Camera and Light classes. It is used by the SPICE utility, spiceypy.spkpos(), as the name for the celestial body whose position will be used as the origin of the reference frame. This corresponds to the obs argument to spiceypy.spkpos(). Please refer to the spkpos documentation for more information.

ref

NAIF reference frame name (str)

This attribute can be used by the subclasses Entity, as well as all Camera and Light classes. It is used by both the SPICE utilities, spiceypy.pxform() and spiceypy.spkpos(), as the name for the reference frame against in which positions and rotations will be calculated. This corresponds to the ref argument to both spiceypy.spkpos() and spiceypy.pxform(). Please refer to the spkpos or pxform documentation for more information.

abcorr

Aberration correction flag (str)

This attribute is used by by the SPICE utility, spiceypy.spkpos(), as an indication of what light time correction should be used. This corresponds to the abcorr argument to spiceypy.spkpos(). Please refer to the spkpos documentation for more information.

set_scale(scale, cpp=True)[source]

Set a new scale

Parameters

scale (float) – Scale to be applied
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True

set_position(position, cpp=True)[source]

Set a new position

Parameters

position (ArrayLike) – Position to be applied (xyz)
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True

set_rotation(rotation, cpp=True)[source]

Set a new rotation

Parameters

rotation (ArrayLike) – 3 by 3 Rotation matrix that must obey \(R^T = R^{-1}\) and \(\det(R)=1\)
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True

set_pose(position, rotation, cpp=True)[source]

Set both a new position and rotation

Parameters

position (ArrayLike) – Position to be applied (xyz)
rotation (ArrayLike) – 3 by 3 Rotation matrix that must obey \(R^T = R^{-1}\) and \(\det(R)=1\)
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True

spice_position(et, cpp=True)[source]

Set new position for a given ephemeris time using SPICE

This is done using spiceypy.spkpos(), where the name is used as the targ argument, ref is used as the ref argument, abcorr is used as the abcorr argument, and origin is used as the obs argument. Please refer to the spkpos documentation for more information.

Parameters

et (float) – Ephemeris time (seconds since the J2000 epoch), also known as Barycentric Dynamical Time
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True

spice_rotation(et, cpp=True)[source]

Set new rotation for a given ephemeris time using SPICE

This is done using spiceypy.pxform(), where the ref is used as the from argument, and frame is used as the to argumnet. Please refer to the pxform documentation for more information.

Parameters

et (float) – Ephemeris time (seconds since the J2000 epoch), also known as Barycentric Dynamical Time
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True

spice_pose(et, cpp=True)[source]

Set both a new position and rotation for a given ephemeris time using SPICE

The position is updated using spiceypy.spkpos(), where the name is used as the targ argument, ref is used as the ref argument, abcorr is used as the abcorr argument, and origin is used as the obs argument.

The rotation is updated using spiceypy.pxform(), where the ref is used as the from argument, and frame is used as the to argumnet.

Please refer to the spkpos or pxform documentation for more information.

Parameters

et (float) – Ephemeris time (seconds since the J2000 epoch), also known as Barycentric Dynamical Time
cpp (bool, optional) – Flag for if the underlying C++ body should be updated
Default: True