Résumé : Cultural Heritage scenes usually consist of very large and detailed 3D objects with high geometric complexity. Even the raw visualization of such 3D objects already involves a large amount of memory and computation time. When trying to improve the sense of immersion and realism by using, global illumination techniques the demand on these resources becomes prohibitive Our approach uses regular grids combined with a vector-based representation to efficiently capture low-frequency indirect illumination. A fixed set of irradiance vectors is stored in 3D textures (for complex objects) and in 2D textures (for mostly planar objects). The vector-based representation offers additional robustness against local variations of the geometry. Consequently, the grid resolution can be set independently of geometric complexity, and the memory footprint can therefore be reduced. The irradiance vectors can be precomputed on a simplified geometry. For interactive rendering, we use an appearance preserving simplification of the geometry. The indirect illumination within a grid cell is interpolated from its associated irradiance vectors, resulting in an everywhere-smooth reconstruction.