Abstract: We present a novel visibility representation, Intersection Field (i-Field), to compute global illumination in interactive rates. The i-Field provides fast visibility and line-scene intersection queries. We factorize the direct illumination into local irradiance and visibility ratio. The latter is efficiently evaluated by querying the i-Field. The indirect illumination is simulated by photon tracing, which is also accelerated by the i-Field. By quickly detecting invalid portions, our approach can handle highly dynamic scenes, allowing light sources and scene geometries to be manipulated at interactive rates through rigid transformations and free deformations.