The pivot was still derived from the binary CH4 >= dc_threshold_mv mask,
so a threshold that happens to leave a real angle's mask empty (signal
levels vary scan to scan across a many-angle acquisition) silently fell
back to the raw scan-window bbox center — reproducing the exact "aligned
to the scan window, not the sample" scatter the centroid pivot exists to
fix, without any visible error.
Replace the binary-mask centroid with an intensity-weighted centroid of
the continuous CH4 signal, which is always well-defined regardless of the
RF-mask threshold in effect. The threshold still controls what the manual
dialog's overlay and CH1 masking show; it no longer has any bearing on
where alignment pivots.
Also bump the sidecar schema version: a file saved before today's pivot
and rotation-sign fixes stores numbers for a since-corrected transform, so
loading it unchanged would reintroduce the same scatter. Old sidecars are
now treated as absent rather than silently reused.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Thomas Ales
8312668c02