Modelling radiative properties of light sources and surfaces

This paper describes methods that can be used for modeling radia-tive properties of light sources and materials, in a radiosity computation algorithm. These methods have been designed in order to improve the photo-realistic rendering of complex architectural scenes as well as to allow illumination engineering applications. They are based on the accurate modeling of the spatial and spectral emittance distributions of the light sources, and the surface reeectance/transmittance distributions from measurement , and allow to calculate the exact colorimetric properties of the light sources and the surfaces. A method for changing radiosity inputs during the radiosity process, without recalculating the solution entirely is also proposed. This allows to simulate modiications in design or dynamic lighting eeects more interactively.