| """Contact detection for markerless GelSight. |
| |
| Provides the classical, calibration-free contact pipeline: |
| diff-from-reference (L2) -> threshold -> largest connected component -> mask, |
| plus the exact contact scalars the dataset ships (intensity/area/mixed) so |
| users can reproduce / recompute them. |
| """ |
| from __future__ import annotations |
|
|
| import numpy as np |
|
|
| from .reference import l2_diff |
|
|
| TAU = 8.0 |
|
|
|
|
| def contact_metrics(frame, reference, tau: float = TAU): |
| """Reproduce the dataset's per-frame contact scalars. |
| |
| d = ||frame - ref||_2 (per pixel, over RGB) |
| intensity = mean(d) |
| area = mean(d > tau) |
| mixed = mean(d * (d > tau)) |
| |
| Matches data/<task>/meta/*.parquet tactile_*_{intensity,area,mixed}. |
| """ |
| d = l2_diff(frame, reference) |
| above = d > tau |
| return { |
| "intensity": float(d.mean()), |
| "area": float(above.mean()), |
| "mixed": float((d * above).mean()), |
| } |
|
|
|
|
| def contact_mask(frame, reference, tau: float = TAU, largest_only: bool = True, |
| min_area_px: int = 50): |
| """Binary contact mask (H, W) bool. |
| |
| diff-from-reference L2 > tau, then (optionally) keep only the largest |
| connected component and drop specks < min_area_px. No calibration needed. |
| """ |
| import cv2 |
| d = l2_diff(frame, reference) |
| mask = (d > tau).astype(np.uint8) |
| if int(mask.sum()) < min_area_px: |
| return np.zeros(mask.shape, bool) |
| if not largest_only: |
| return mask.astype(bool) |
| n, lbl, stats, _ = cv2.connectedComponentsWithStats(mask, connectivity=8) |
| if n <= 1: |
| return np.zeros(mask.shape, bool) |
| areas = stats[1:, cv2.CC_STAT_AREA] |
| keep = int(areas.argmax()) + 1 |
| out = lbl == keep |
| return out if out.sum() >= min_area_px else np.zeros(mask.shape, bool) |
|
|
|
|
| def contact_centroid(mask): |
| """(row, col) centroid of a contact mask, or None if empty.""" |
| ys, xs = np.nonzero(mask) |
| if len(ys) == 0: |
| return None |
| return float(ys.mean()), float(xs.mean()) |
|
|
