Abstract: Light transport simulation is an important component of realistic image synthesis. The body of research work related to this phenomenon is referred as global illumination and, despite its well known physics laws, remains a challenging problem due to its high computational cost, with even more critical consequences for real-time scenarios. We present here a novel approach to address the real-time global illumination problem using forward rendering techniques. We focus on unshadowed diffuse interaction for the first indirect light bounce in the context of large models such as the complex scenes usually encountered in CAD application scenarios. We propose an approach, inspired from light cuts [Walter et al. 2005], which efficiently generates on-the-fly a fast, multiscale and temporally coherent radiance cache by exploiting the geometry-specific stages of the graphics pipeline, namely the tessellator unit and the geometry shader. Our probabilistic solution is supported by a mathematical analysis and a number of experiments covering a wide range of application scenarios. Moreover, no precomputation is needed and our solution is compatible with dynamic view point, lighting condition, geometry and materials.