Multi resolution infrared optical properties for Gaussian sea surfaces

We are interested in the infrared radiative modelling of wind-roughened Gaussian sea for surface length from one meter to several kilometers. For the considered spectral bandwidth, the relations beween geometrical optics and global optical properties are already known for centered Gaussian sea surface. In our case, for resolutions under sea correlation length, processes have non-zero mean value and literature's expressions are incomplete. Thus, we extend them to account for any surface length. Hiding and shadowing are included. Only single reflections are treated. The numerical method requires the mean vector-valued and covariance matrix of slopes processes for any resolution. To estimate those parameters, a new two-scale method is introduced, combining statistical approach with geometrical surface generation: the "variable step method". Finally, illustrations show our ability to produce good quality ocean scenes in various contextual conditions.