ParallelHoleCollimatorGeometry¶

class odl.tomo.geometry.spect.ParallelHoleCollimatorGeometry(apart, dpart, det_radius, axis=(0, 0, 1), **kwargs)[source]¶

Bases: odl.tomo.geometry.parallel.Parallel3dAxisGeometry

Geometry for SPECT Parallel hole collimator.

For details, check the online docs.

Attributes

angles: All angles of this geometry as an array.
axis: Normalized axis of rotation, a 3d vector.
check_bounds: If True, methods computing vectors check input arguments.
det_axes_init: Initial axes of the detector.
det_grid: Sampling grid of det_params.
det_params: Continuous detector parameter range, an IntervalProd.
det_partition: Partition of the detector parameter set into subsets.
det_pos_init: Initial position of the detector reference point.
det_radius: Radius of the detector orbit.
detector: Detector representation of this geometry.
grid: Joined sampling grid for motion and detector.
implementation_cache: Dictionary acting as a cache for this geometry.
motion_grid: Sampling grid of motion_params.
motion_params: Continuous motion parameter range, an IntervalProd.
motion_partition: Partition of the motion parameter set into subsets.
ndim: Number of dimensions of the geometry.
orig_to_det_init: Unit vector from rotation center to initial detector position.
params: Joined parameter set for motion and detector.
partition: Joined parameter set partition for motion and detector.
translation: Shift of the origin of this geometry.

Methods

`det_axes`(self, angle)	Return the detector axes tuple at `angle`.
`det_point_position`(self, mparam, dparam)	Return the detector point at `(mparam, dparam)`.
`det_refpoint`(self, angle)	Return the position(s) of the detector ref.
`det_to_src`(self, angle, dparam)	Direction from a detector location to the source.
`frommatrix`(apart, dpart, det_radius, …)	Create a `ParallelHoleCollimatorGeometry` using a matrix.
`rotation_matrix`(self, angle)	Return the rotation matrix to the system state at `angle`.

__init__(self, apart, dpart, det_radius, axis=(0, 0, 1), \*\*kwargs)[source]¶

Initialize a new instance.

Parameters

apart1-dim. RectPartition: Partition of the angle interval.
dpart2-dim. RectPartition: Partition of the detector parameter rectangle.
det_radiuspositive float: Radius of the circular detector orbit.
axisarray-like, shape (3,), optional: Vector defining the fixed rotation axis of this geometry.

Other Parameters

orig_to_det_initarray-like, shape (3,), optional: Vector pointing towards the initial position of the detector reference point. The default depends on axis, see Notes. The zero vector is not allowed.
det_axes_init2-tuple of array-like’s (shape (3,)), optional: Initial axes defining the detector orientation. The default depends on axis, see Notes.
translationarray-like, shape (3,), optional: Global translation of the geometry. This is added last in any method that computes an absolute vector, e.g., det_refpoint, and also shifts the axis of rotation. Default: (0, 0, 0)
check_boundsbool, optional: If True, methods perform sanity checks on provided input parameters. Default: True

Notes

In the default configuration, the rotation axis is (0, 0, 1), the vector towards the initial detector reference point is (0, 1, 0), and the default detector axes are [(1, 0, 0), (0, 0, 1)]. If a different axis is provided, the new default initial position and the new default axes are the computed by rotating the original ones by a matrix that transforms (0, 0, 1) to the new (normalized) axis. This matrix is calculated with the rotation_matrix_from_to function. Expressed in code, we have

init_rot = rotation_matrix_from_to((0, 0, 1), axis)
orig_to_det_init = init_rot.dot((0, 1, 0))
det_axes_init[0] = init_rot.dot((1, 0, 0))
det_axes_init[1] = init_rot.dot((0, 0, 1))