structured_light op• Data kinds: image2d × image2d → image2d
• Call: import fullseye as fs; fs.ledger.absolute_phase(wrapped, coarse) -> 'np.ndarray' (to call the implementation directly, import fringe; fringe.absolute_phase(wrapped, coarse) -> 'np.ndarray'; from the registry, ops3d.get("absolute_phase"))
Turn a wrapped phase into an absolute one by fixing its fringe order from a coarse but absolute phase estimate.
Φ = wrapped + 2π·round((coarse − wrapped) / 2π)
wrapped: output of wrapped_phase, a 2D array in (-π,π] (high precision, no absolute order).
coarse: 2D array of the same shape. An absolute but coarse phase estimate [rad]. Typically the projector
column number decoded with Gray code, converted to phase (2π·freq·col/width). NaN allowed (output also NaN).
Returns: absolute phase [rad] (2D float64). Invalid pixels (either is NaN) are NaN.
Why it is needed (difference from spatial unwrapping): unwrap_phase_2d follows adjacent pixels to bridge 2π jumps, so (a) a global offset +2πm remains, and (b) the order cannot propagate between islands cut apart by occlusion. This op determines the order independently per pixel, so it is absolute even in scenes split into islands, and needs no propagation. In exchange, the error of coarse must be less than half a period (π).
Requirement (fail-closed): |coarse − Φ_true| < π. If this is violated, round picks the neighbouring order and that pixel alone silently shifts by 2π (= the depth of 1 fringe). Choose the fringe count freq so that the coarseness of the Gray code (±0.5 column), converted to phase, does not exceed half a period (e.g. projector width 512 px, freq 24 → 1 period 21.3 px, Gray's ±0.5 px is comfortably inside).
Raises: ValueError on shape mismatch, not 2D, or wrapped far outside (-π,π].
Provenance (public literature): the combined method that obtains absolute phase from Gray code plus phase shifting — Sansoni et al., *Appl. Opt.* 38(31) 1999 / Zhang, *Opt. Lasers Eng.* 48 2010 (review). Projection of the Gray code itself: Inokuchi et al., *ICPR* 1984.
• depth_sensors — Depth sensors — ranging principles, real-device figures, how dropouts appear
• 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.
• structured_light_scan — py -3.11 examples_3d/structured_light_scan.py
image2d as input)fuse_to_voxel · fit_poly_surface · eval_poly_surface · surface_form_error · background_flatten · polar_unwrap · fit_zernike · matcap_shade
structured_light)wrapped_phase · unwrap_phase_2d · graycode_decode · decode_fringe · synthesize_fringes · triangulate_column
*Provenance: fringe.py — 3D 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.