Where the bands come from. The ideal ranges are not invented. They are fitted on SCUT-FBP5500 — 5,500 frontal faces, each rated by 60 volunteers (330,000 ratings, IEEE ICPR 2018) — restricted to the 2,750 male faces. For each measurement the band is the median and interquartile range of the best-rated 20% of faces, and its importance weight is the effect size (Cohen's d) between the best- and worst-rated fifth. The PSL bucket is a percentile of that reference population, so the scale is a distribution rather than an arbitrary linear map.

What that is worth. The per-feature band score agrees with the human mean rating at r = 0.43 on held-out faces. The hand-written rubric it replaced scored r = −0.09, i.e. slightly anti-correlated. The joint model shown on the right reaches r = 0.73 as shipped (0.75 in-fit, before dropping race to a population mean). Two measurements are excluded from scoring because they were measured to be invalid: the upper third (the mesh top is the forehead, not the trichion) and symmetry (which behaves as a template-fit residual, not asymmetry).

Method. MediaPipe FaceLandmarker gives 468 mesh vertices plus 10 iris points in 3-D, averaged over five rotation-jittered passes. Landmarks are converted to one isotropic unit, the canonical 468-vertex face model is fitted (Horn quaternion / Kabsch), that rigid transform is inverted, and the ratios are measured in the canonical frontal plane.