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Add caveat on 3D X-ray projector #554

Merged
merged 3 commits into from
Sep 25, 2024
Merged

Add caveat on 3D X-ray projector #554

merged 3 commits into from
Sep 25, 2024

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Michael-T-McCann
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@Michael-T-McCann Michael-T-McCann commented Sep 19, 2024

Add caveat on 3D X-ray projector.

@@ -235,6 +235,9 @@ def _calc_weights(
class XRayTransform3D(LinearOperator):
r"""General-purpose, 3D, parallel ray X-ray projector.

Warning: This class is experimental and may be up to ten times slower
than :class:`scico.linop.xray.astra.XRayTransform3D`.
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Perhaps add some positive aspects, e.g. "It is expected to be useful for small problems as, unlike :class:scico.linop.xray.astra.XRayTransform3D, it can be run on both CPU and GPU, and the forward and adjoint transforms are differentiable." [The differentiable claim should be confirmed before inclusion!]

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Differentiable wrt to x, definitely, but so is scico.linop.xray.astra.XRayTransform3D in the way we've wrapped it. I'm not sure about differentiable wrt to the angles. I'd like to call that out of scope for this PR.

How about

This projector approximates cubical voxels projecting onto rectangular pixels and provides a back projector that is the true adjoint of the forward projector. It is written purely in JAX, allowing it to run on either CPU or GPU and minimizing host copies.

Warning: This class is experimental and may be up to ten times slower than scico.linop.xray.astra.XRayTransform3D.

@bwohlberg bwohlberg added the documentation Improvements or additions to documentation label Sep 25, 2024
@bwohlberg bwohlberg merged commit dc9baee into main Sep 25, 2024
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@bwohlberg bwohlberg deleted the mike/caveat branch September 25, 2024 16:11
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2 participants