contact_patch_radius — DRIVE tacdome op

• Data kinds: image2d × scalar → table

• Call: import fullseye as fs; fs.ledger.contact_patch_radius(img, pitch: 'float', ring_px: 'float' = 4.0) -> 'dict' (to call the implementation directly, import tacdome; tacdome.contact_patch_radius(img, pitch: 'float', ring_px: 'float' = 4.0) -> 'dict'; from the registry, opsdrive.get("contact_patch_radius"))

Usage

Reads the contact radius from a contact image (of the dome_contact_image type). Uses the edge down to subpixel level via a linear sum of coverage (area method).

1) A rough disc with threshold (1 % point + 99.9 % point)/2 → centroid and radius r_t. 2) fg = median of the inside r < r_t − ring_px, bg = median of the outer ring

r_t + ring_px to r_t + 2·ring_px. 3) Sum the coverage (I − bg)/(fg − bg) over r < r_t + ring_px without clipping (clipping biases the noise to one side) → a = pitch·√(Σ/π); the centroid is weighted by coverage. Returns: a, a_px, a_threshold (circle of the thresholded pixel count), centre (row, col), fg, bg, edge_points (boundary pixels (row, col) of the thresholded disc, can be passed to measure.fit_circle). Raises ValueError: not 2-D, no bright disc (contrast 0), disc too small (r_t < 3 px) or touching the window edge.

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• poc_tacdome_large_deformation — py -3.11 examples/poc_tacdome_large_deformation.py

Ops the type connects to (they accept table as input)

course_layout · course_occupancy · course_contains · world_build · world_camera · world_move · lidar_scan · rss_longitudinal_same

Same category (tacdome)

powerlaw_linear_contact · largedef_correction · largedef_radius_ratio · largedef_universal_correction · large_deformation_contact · large_deformation_inverse · mdr_spring_bed · neohookean_cylinder_exact

*Provenance: tacdome.py — DRIVE operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.