Gluteal projection
The perpendicular distance from the seat apex to the reference plane. Projection sets how much fabric the cut must supply before any strain appears.
Rear-fit science
Four quantities do most of the work in rear-seat fit: how far the seat projects, whether the surface curves smoothly into the yoke, what the pocket does under load, and how much strain the interface carries. This page steps through how each is captured and scored.
A single calibrated still or a short scan gives a set of surface points. Nothing is inferred yet — this stage only records where the fabric sits.
The perpendicular distance from the seat apex to the reference plane. Projection sets how much fabric the cut must supply before any strain appears.
Smooth fits keep the tangent continuous across the seam (C¹). A break forces the eye — and the load — onto one line, which is where wear starts.
Under load the pocket mouth sags and its base stretches. PDI is the normalised change in that region against the unloaded state.
The stretch the seam and waistband carry when the garment is worn. Unlike projection, strain is a property of the pair — garment and body.
| Index | Definition | Typical range | Status |
|---|---|---|---|
| UC | Upper curvature continuity across the seat seam | 0.86 – 1.00 | MODELED |
| LC | Lower curvature continuity into the thigh | 0.80 – 0.98 | MODELED |
| P | Projection, apex to reference plane | 10.2 – 12.8 in | MODELED |
| CCF | Curvature continuity factor (composite) | 0.88 – 1.00 | MODELED |
| PDI | Pocket deformation index | 0.62 – 0.97 | MODELED |
| ISI | Interface strain index | 0.40 – 0.90 | MODELED |
Ranges describe the model’s operating envelope, not a population. These are derived outputs of the CNF v1.2 framework.
The Studio shows all six updating in real time on a modeled surface.
Independent. BBMB is not affiliated with, endorsed by, sponsored by, or certified by Levi Strauss & Co. or any other denim brand. Diagrams are schematic and the indices are modeled outputs of this lab’s own framework, not measurements of any individual.