Please check: https://imaging.cs.cmu.edu/rrte/ for more details
@article{pediredla2020path, title={Path tracing estimators for refractive radiative transfer}, author={Pediredla, Adithya and Chalmiani, Yasin Karimi and Scopelliti, Matteo Giuseppe and Chamanzar, Maysam and Narasimhan, Srinivasa and Gkioulekas, Ioannis}, journal={ACM Transactions on Graphics (TOG)}, volume={39}, number={6}, pages={241--1}, year={2020}, publisher={ACM New York, NY, USA} }