Rear-Geometry Metrics Explained

Seat Curvature

Cross-sections are sampled at heights z_k across the rear surface. Curvature at each sample:

κ(z_k) = d²y/dx² / (1 + (dy/dx)²)^(3/2)

Mean curvature and std describe the overall contour. Samples are stored as (z, curvature) pairs for downstream tension modeling.

Projection Vector

Projection depth measures how far the rear surface extends forward relative to the pelvis plane:

p_max = max_i n · (v_i − v_pelvis)

Mean and std characterize projection, while peak captures maximum forward excursion. Vicente centroid: ~27.5 mm ± 4 mm.

Cloth-Body Distance Field

For each cloth surface point u_j, the distance to the body mesh M_b is:

d_j = || u_j − Π(u_j, M_b) ||

These distances are binned into tight, regular, and relaxed zones. Zone ratios define FitBand behavior and tension risk.

Sampling & Stability

• Samples are resampled per frame for dynamic poses.
• Contour stability = cosine similarity between consecutive curvature vectors.
• High contour stability (≥ 0.90) is required for Master Mold candidacy.