The creation and rendering of realistic water scenes is one of the challenging tasks in Computer Graphics. To reproduce the illumination and color inside water bodies an algorithm capable of dealing with media with anisotropic and multiple scattering has to be used. We have developed a simulation system, CORDIS, based in the discrete ordinates method to solve the problem of light transport in general participating media. The system is adequate to treat complex participating medium such as natural waters as it is prepared to deal with, not only anisotropic, but highly-peaked phase functions as
well as to considered the spectral behavior of the medium’s characteristic parameters. It is also able to generate not only
synthetic images but detailed quantitative illumination information, so as the amount of light that reaches the medium boundaries or the amount of light absorbed in each of the medium voxels. The system considers objects and light sources inside the water, works with realistic spectral medium parametrizations (bio-optical models) and can be extended to consider not only elastic but inelastic processes such as fluorescence.