material op• Data kinds: rgbimage → rgbimage
• Call: import fullseye as fs; fs.ledger.wetness(base_rgb, wet=1.0, ior=1.33) -> 'np.ndarray' (to call the implementation directly, import surfacelib; surfacelib.wetness(base_rgb, wet=1.0, ior=1.33) -> 'np.ndarray'; from the registry, opsoptics.get("wetness"))
The base colour of a wet surface. The diffuse gets darker (and the specular grows).
base_rgb: colour in the dry state (H,W,3) or (3,). wet: wetness (0–1).
ior: refractive index of the water film.
Returns: diffuse colour in the wet state (same shape).
Why it darkens: total internal reflection occurs inside the water film, diffuse light is sent back to the surface again and again and absorbed each time. As an approximation, for the dry reflectance ρ a re-absorption corresponding to the internal reflectance Ri = 1 − (1 − Ri0)/n² is applied ―― exactly the phenomenon of wet sand looking dark (the increase in specularity is expressed by layering clearcoat_shade(coat=wet)).
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.
• machined_metal_and_materials — py -3.11 examples/machined_metal_and_materials.py
rgbimage as input)clearcoat_shade · defocus_blur · diffraction_blur · sensor_capture
material)material_catalog · oren_nayar · clearcoat_shade · sheen_shade · subsurface_approx
*Provenance: surfacelib.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.