watermedia op• Data kinds: none → table (an op determined by its arguments alone — it takes no image or data input)
• Call: import fullseye as fs; fs.ledger.water_attenuation(wavelength_um, water_type='pure', depth_m=None) -> 'dict' (to call the implementation directly, import watermedia; watermedia.water_attenuation(wavelength_um, water_type='pure', depth_m=None) -> 'dict'; from the registry, opsoptics.get("water_attenuation"))
• GPU: none (CPU reference implementation only)
Absorption, scattering and diffuse attenuation of water, and the transmittance over depth -> dict.
water_type="pure": the absorption a is the integrating-cavity measurement of Pope & Fry (1997), 380-727.5 nm (minimum 0.00442 /m at 417.5 nm, 0.624 /m at 700 nm), interpolated linearly in wavelength; the scattering b is the pure-water law of Smith & Baker (1981), b = 0.00288 (lambda / 500 nm)^-4.32 per metre; the diffuse attenuation is approximated as Kd = a + b_b with b_b = b / 2 (a flat-sky approximation, flagged in kd_is_approximation). water_type="jerlov_I" ... "jerlov_9C" (IA, IB, II, III, 1C, 3C, 5C, 7C, 9C): the Jerlov (1976) optical water types, with a, b and Kd as assigned by Solonenko & Mobley (2015) at 400-700 nm in 25 nm steps, interpolated linearly; the paper gives no value for 3C above 650 nm and 5C above 575 nm, and asking for one is refused. The scattering of types I and IA is flagged by the authors as inconsistent with their own constants (b_suspect). An unknown type is refused with the list of known ones; so is a wavelength outside the table. c = a + b. depth_m (a scalar or a 1-D array of depths, m) adds transmittance = exp(-Kd z), the fraction of the downwelling light left at depth z (shape (nz, nw), or (nw,) for a scalar). The table has wavelength_um, a, b, c, kd (all per metre), transmittance, water_type, known_types, b_suspect and kd_is_approximation.
Every optics op validates its input before computing (nothing slips through silently):
• Units are baked into the argument name — _mm / _um / _deg / _mrad. Confusing mm with µm does not crash; it yields a plausible-looking wrong answer, so the name prevents it. Nothing here guesses the unit from the magnitude.
• Strings raise ValueError — float('50') succeeds, so an unparsed configuration value would slip through as a length (measured: thin_lens('50', '200') returned a plausible 66.667 mm). bool is refused too, as the implicit promotion True == 1.
• complex / masked arrays raise ValueError (real-valued slots only; silently dropping the imaginary part or peeling off the mask is refused). NaN/Inf raises ValueError on every input.
• Division by zero and its relatives are refused by name: focal length 0, radius of curvature 0, refractive index <= 0, a fully opaque aperture (all zeros, so the normalisation is 0/0), a PSF whose sum is <= 0, a Stokes vector with S0 = 0, and an object sitting at the front focal point (the image is at infinity).
• Only two ops return a non-finite value, and both state it as a contract: depth_of_field returns far_mm = inf beyond the hyperfocal distance (that is what the hyperfocal distance means), and gaussian_beam returns wavefront_radius_mm = inf at the waist (the radius of curvature of a plane wavefront). Both also return a finite companion (far_is_infinite / curvature_per_mm). Any other silent NaN/Inf is detected internally and raises ValueError — "float64 overflowed" and "the answer is infinite" are different claims, so the first is never returned wearing the face of the second.
• Size caps: generated grids are capped by optics.MAX_GRID (4096); supplied fields/PSFs/apertures by optics.MAX_FIELD_ELEMENTS (2^24); ABCD element chains by optics.MAX_SYSTEM_ELEMENTS (1024); Zernike by MAX_ZERNIKE_TERMS (512) / MAX_ZERNIKE_ORDER (40) / MAX_ZERNIKE_BASIS (2^25). This closes, fail-closed, the paths where a small argument triggers a huge internal allocation (measured: n_max=40 × 4096² needs 108 GB).
• Physically impossible states are refused too: a Stokes vector with degree of polarisation > 1, negative transmittance, negative intensity, and invalid Zernike indices such as n-|m| odd.
• 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.
• poc_geodetic_height_frames — py -3.11 examples/poc_geodetic_height_frames.py
• poc_water_inspection_images — py -3.11 examples/poc_water_inspection_images.py
• poc_water_transparent_media — py -3.11 examples/poc_water_transparent_media.py
table as input)abcd_matrix · wavefront_stats · sfr_from_edge · paraxial_trace · seidel_coefficients · spot_stats · tolerance_analysis · wavefront_from_opd
watermedia)ocean_spectrum · ocean_height_field · fresnel_water_air · snell_window · refracted_view · underwater_image · phase_function_hg · scattering_phase_petzold
*Provenance: watermedia.py — OPTICS 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.