Rotation scaling gained a third cross-validated correction surface alongside
decay and absorption: a smooth multiplicative factor over the predicted detector
position (px, py) where each full lands. It absorbs detector-response and
geometric flat-field systematics that vary across the detector plane and inflate
R-meas; symmetry-equivalents of one reflection land at different detector
positions as the crystal rotates, over-determining the surface. Because it lives
in the detector frame (not the rotation), the same correction concept applies to
stills.
The surface fit/cross-validate/apply machinery shared with the absorption surface
is factored into ApplyCellSurface; RefineAbsorption and the new RefineModulation
just build their per-full cell assignment (goniometer-frame vs detector-frame)
and call it. The cross-validation now scores a sigma-INDEPENDENT, R-meas-like
fractional agreement of the held-out equivalents rather than a studentized chi^2,
so a surface can no longer pass CV by reshaping sigma without tightening the
intensities - this removes an over-fit regression on mis-indexed data and hardens
the absorption surface too.
On the /data/rotation_test rotation battery (A/B, modulation off vs on): 17 of 22
processed crystals improve R-meas, 0 regress, e.g. lysoC 23.2->16.3%, lyso_2
47.4->28.5%, EcwtAL500 53.2->27.6%, EP_cs_01-17 CC1/2 60->93%; CC1/2 held or
improved everywhere and the anomalous S signal preserved/improved (lyso_ref
SD_MET 4.37->4.46, lysoC 3.07->3.25). On by default with the other surfaces.
Also: --dump-observations now writes the per-full centroid frame and predicted
px/py columns, so the dumped combined fulls are a complete unmerged export.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
leonarski_fandClaude Opus 4.8
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