Sbert, Mateu2015-02-152015-02-1519971467-8659https://doi.org/10.1111/1467-8659.00167In this paper we study how to optimally select between different sources in shooting random walk Monte Carlo Radiosity. Until now the probability of selecting a source has been made proportional to the importance of that source for the region of interest. We will show here that, whenever the transition probabilities are the Form Factors, this is not optimal, and will consequently give the optimal case. This will correspond to probabilities proportional to the square root of importances, rather than to importances themselves.10.1111/1467-8659.00167C301-C308