Fast BRDF model for sea-surface foam media toward optical remote sensing and imaging simulation

Sea-surface foam and near-surface bubbles strongly affect the bidirectional reflectance distribution function (BRDF) of the ocean surface under high-sea-state conditions, but direct Monte Carlo radiative transfer is computationally prohibitive for repeated pixel-wise hyperspectral imaging simulations. This paper proposes a fast BRDF surrogate model for sea-surface foam media. A coupled foam-bubble photon-transport framework generates Monte Carlo BRDF and energy partitioning labels, and a physics-constrained surrogate model predicts directional reflectance from foam thickness, wavelength, temperature, salinity, and illumination-viewing geometry. Validation using independent Monte Carlo samples, parameter-response analysis, and computational efficiency tests shows that the model captures the main angular and spectral reflectance trends while substantially reducing computational cost.