Hi @Jimbohalo10, Thanks for your great work. Loushuang’s GPULightmass is more like CPULightmass, it calculate the GI use GPU insteas of CPU, they use the same method. Because the GPU is more effetive in mutil-calculate,so it will be more quickly. The Epic’ GPULightmass use RayTracing calculate the GI. Is that right ?