Fix Parallel2D system_description precision error#2316
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Signed-off-by: Laura Murgatroyd <60604372+lauramurgatroyd@users.noreply.github.com>
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Hi @gfardell, I think we need to change the code.
Please can you expand on what the issue was that you encountered?
| if abs(dot_product) < 1e-8: | ||
| return SystemConfiguration.SYSTEM_SIMPLE |
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What about a case where the detector and rotation axis are offset on the y axis. Shouldn't that also be system_simple?
e.g.
AG = AcquisitionGeometry.create_Parallel2D(detector_position=[0,10], rotation_axis_position=[0,0])
self.assertTrue(AG.system_description=='simple')
currently fails (and I think we should add it as a unit test)
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I think the previous code worked as expected because it checked if all vector values were equal and if not, checked the difference vector was parallel to the ray direction
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Good catch. We don't set detector position in many parallel cases so I didn't spot it.
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The issue is that https://github.com/gfardell/CIL/blob/a4e2b29eab32aa5fefc11dc02584d762c601729f/Wrappers/Python/cil/framework/acquisition_geometry.py#L52 is returned if the points are equal to a tolerance, that wasn't a tighter tolerance than the code route that called it. |
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Ok, so could changing this tolerance be a possible solution? https://github.com/gfardell/CIL/blob/a4e2b29eab32aa5fefc11dc02584d762c601729f/Wrappers/Python/cil/framework/acquisition_geometry.py#L49 |
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Changes
Fixed Parallel2D geometry raising exception in system_description due to near-zero vector when rotation axis and detector positions are close but not equal.
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