Projectors

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Projectors#

Projectors implement a tomographic forward projection or backprojection. In KernelKit, the projector objects manage the execution of a kernel and handle the geometries and data.

Overview#

Currently added are the 3D forward projector and backprojectors.

Forward projectors

kernelkit.ForwardProjector

A projector for a list-based scan geometry and single 3D reconstruction volume.

Backprojectors

kernelkit.BackProjector

A backprojector for a list-based scan geometry and single 3D volume.

Usage#

Projectors follow a simple interface, with getters, setters and deleters backing volume_geometry, projection_geometry, volume and projections. This is easiest to explain with an example:

# 1. Creating a forward projector.
#    Passed arguments are used for compiling an optimal kernel.
#    Here, the input is set to (z, y, x) axis order.
fp = kk.ForwardProjector(volume_axes=(2, 1, 0))

# 2. Setting attributes
fp.volume_geometry     = vg
fp.projection_geometry = pg
fp.volume              = cp.asarray(x, dtype=cp.float32)
fp.projections         = cp.empty((3, det.rows, det.cols), dtype=cp.float32)

# 3. Calling the object executes the projector
#    and stores the output in `projections`.
fp()

# 4. Attribute getters allow you to retrieve the object
y = fp.projections

A full example is found at example/tutorials/projectors.ipynb.

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