[PIPE2D-926] Make slit offset measurement more robust Created: 27/Oct/21  Updated: 19/Nov/21  Resolved: 19/Nov/21

Status: Done
Project: DRP 2-D Pipeline
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Story Priority: Normal
Reporter: price Assignee: price
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Story Points: 2
Sprint: 2DDRP-2021 A11
Reviewers: hassan

 Description   

When running reduceArc.py, the results obtained with fitDetectorMap.doSlitOffsets=True are typically much worse than with False. I attribute this to lack of robustness in the slit offset measurement. The SplinedDetectorMap::measureSlitOffsets doesn't do any rejection of outliers. DistortionBasedDetectorMap::measureSlitOffsets uses SplinedDetectorMap::measureSlitOffsets but in the end the slit offsets don't change. Finally, consider moving the measurement of the slit offsets to after the distortion measurement rather than before.



 Comments   
Comment by price [ 18/Nov/21 ]

I'm really happy with the results. Below is what I get on the PFI arcs: the 0.04 pixel residual error is reduced to 0.01.

reduceArc.py /projects/HSC/PFS/Subaru --calib /projects/HSC/PFS/Subaru/CALIB-PFI-20211108 --rerun price/pipe2d-926 --id visit=68096..68100 arm=r -j 10 -c reduceExposure.isr.doFlat=False fitDetectorMap.doSlitOffsets=True
[...]
reduceArc.fitDetectorMap INFO: Final fit: chi2=213531.525274 dof=136524 xRMS=0.052833 yRMS=0.051992 (0.004489 nm) xSoften=0.043156 ySoften=0.042405 from 68292/69153 lines
reduceArc.fitDetectorMap INFO: Fit quality from reserved lines: chi2=66920.399276 xRMS=0.059545 yRMS=0.057841 (0.004994 nm) xSoften=0.083305 ySoften=0.066542 from 7684 lines (10.0%)
reduceArc.fitDetectorMap INFO: Softened fit: chi2=136464.653763 dof=136524 xRMS=0.054736 yRMS=0.053694 (0.004636 nm) xSoften=0.043148 ySoften=0.042385 from 7684 lines
reduceArc.fitDetectorMap INFO: Softened fit quality from reserved lines: chi2=39015.828882 xRMS=0.059519 yRMS=0.057707 (0.004982 nm) xSoften=0.083298 ySoften=0.066536 from 7684 lines
reduceArc.fitDetectorMap INFO: Slit offsets measurement: chi2=52070.972753 dof=115592 xRMS=0.029637 yRMS=0.028872 xSoften=0.008566 ySoften=0.008473 from 58388/68292 lines
reduceArc.fitDetectorMap INFO: Unable to measure slit offsets for 24 fiberIds: [1, 3, 45, 92, 114, 137, 184, 204, 229, 273, 280, 309, 314, 316, 336, 359, 370, 382, 426, 471, 515, 560, 607, 651]
reduceArc.fitDetectorMap INFO: Final result: chi2=437360.934112 dof=135340 xRMS=0.017951 yRMS=0.018199 xSoften=0.011498 ySoften=0.011607 from 68292 lines
Comment by hassan [ 19/Nov/21 ]

No comments on the suggested changes in the pull request. Would be good to see what the residual error is for the b band also. This can be looked at later however.

Comment by price [ 19/Nov/21 ]

We'll worry about the blue-side stats after PIPE2D-948.

Merged.

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