Erratum for Practical Path Guiding for Efficient Light-Transport Simulation

In the original publication, which is available in the Wiley Online Library, the comparison against the method of Vorba et al. [2014] was inaccurate. We used the authors' publicly available code that was not designed to handle two-sided BRDFs. This limitation surfaced in the KITCHEN scene introducing bias, which we incorrectly attributed to the instability of expectation-maximization used to fit GMMs. Furthermore, the implementation did not parallelize well up to the amount of threads we used in our comparisons (48). After discovering these issues, we worked closely with Sebastian Herholz and Jiri Vorba on fixing them. Unfortunately, the training component of their method still does not scale well beyond 8 threads; the training timings could thus be in theory up to 6 times faster. We updated the results in the authors' version of our paper and supplementary materials and adjusted the wording to emphasize that the differences between the two methods are smaller than reported in the original publications. We also removed the claim of the method by Dahm and Keller [2017] being biased and using an exponential moving average to estimate the final pixel values. The authors' version contains all these improvements and is available here alongside the original publication.