SpecularReflectionPositionCorrect algorithm

[Owen Arnold]

We can use the specular reflection condition to correct detector positions for both point detectors and multi detectors.

Some of this functionality is already done in ReflectometryReductionOne, but is more generally useful than just applied there. This algorithm can then be used in ReflectometryReductionOne. It should also be much much easier to test this functionality if it's provided as a separate algorithm.

[Owen Arnold]

refs #9389. New algorithm created.

Basic destructive unit tests added.

Changeset: 508207651f6d83ab70a0ad879cf2b6fefd701f6b

[Owen Arnold]

refs #9389. Vertical correction working for single detector.

Changeset: 48acf640ce99dedcccc5c62086dd61577f31e053

[Owen Arnold]

refs #9389. Implement moveComponent and test.

Changeset: 35bd96436b166f683d6548c6a0a3f402e2d4cdca

[Owen Arnold]

refs #9389. Offseting working for linear as well as point detectors.

Changeset: 90119d673881fbf87a71a4fb55f4589047a37b13

[Owen Arnold]

refs #9389. Better documentation and testing.

Changeset: 959b055e1b00681f6eb576b4d45effc1bdb8a864

[Owen Arnold]

refs #9389. Make input workspaces on the fly.

It's actually only the detector positions that we care about in this algorithm. Data is not important. Therefore use LoadEmptyInstrument to indicate to future users and maintainers that this is the case. Should also be quicker than running Load.

Changeset: 05b8f74748e18530fdf3e8b0fe46df40dd1c21cd

[Owen Arnold]

refs #9389. Fix warnings.

Changeset: 1f409d36caad8188c74cbf49c30492195adc3269

[Owen Arnold]

refs #9389. Fix more warnings.

Changeset: 9c86927092722f7acbfe9a39910b32ba0e76b376

[Owen Arnold]

refs #9389. Fix type conversion warnings.

Changeset: 52db76ce7571360fdc6a7ccec3c61b08531d988c

[Owen Arnold]

refs #9389. Fix type dereferencing rules.

Changeset: a147487b4f0979a34789ce48001bce5bdcdd0442

[Owen Arnold]

Tester: The following shows this working. The unit tests also provide extensive testing scenarios.

import os

def sample_detector_vector(ws):
        inst = ws.getInstrument()
        refFrame = inst.getReferenceFrame()
        detector_pos= inst.getComponentByName('point-detector').getPos()
        sample_pos = inst.getComponentByName('some-surface-holder').getPos()
        sample_to_detector = detector_pos - sample_pos
        return sample_to_detector
        
        
inst_dir = config.getInstrumentDirectory()
file = os.path.join(inst_dir, 'POLREF_Definition.xml')
ws = LoadEmptyInstrument(file)

MoveInstrumentComponent(ws, 'point-detector', RelativePosition=False, X=1)
MoveInstrumentComponent(ws, 'some-surface-holder', RelativePosition=False, X=0)

print "Before Correction: ", sample_detector_vector(ws)

ws = SpecularReflectionPositionCorrect(ws, 45, DetectorComponentName='point-detector', SampleComponentName='some-surface-holder')

print  "After Correction: (45 degree angle)", sample_detector_vector(ws)

[Owen Arnold]

(In #9401) This is actually blocked by #9389, because in order to fix this in a general way, we need to be able to determine an averaged vertical detector location as well as the sample location. The code to do this is already in SpecularReflectionCorrectPositions (9389).

• A first step to getting this done will be to extract out an algorithm base class called SpecularReflectionAlgorithm from SpecularReflectionCorrectPositions. This will provide two protected method and will otherwise virtual. Two methods are getDetectorComponent() and getSampleComponent()
• Next step is to use the base class to create a new algorithm called SpecularReflectionCorrectTheta, which will use this base class.
• Next step is to wire this algorithm into ReflectometryReductionOne to replace to existing correction logic.

[Peter Parker]

Code looked fine to me. Unit tests are passing and seem to offer good coverage.

I had a play with the script, changing the magnitude and direction of the initial sample-detector vector, and those changes gave me different results. There was no change in result for vectors in the Y-direction, but if I've understood the code correctly this is expected (as they lie "across" the beam).

[Peter Parker]

Merge remote-tracking branch 'origin/feature/9389_correct_positions_refl'

Full changeset: ​47f57aec41e954f7b94d3f2ad73cea1c859d9b48

[Stuart Campbell]

This ticket has been transferred to github issue ​10232