For the program written in C++, please cite:
Y. Xu, S. Li, H. You, Z. He and Z. Su, "Retrieval of Canopy Gap Fraction From Terrestrial Laser Scanning Data Based on the Monte Carlo Method," in IEEE Geoscience and Remote Sensing Letters, vol. 19, pp. 1-5, 2022, Art no. 3001905, doi: 10.1109/LGRS.2021.3061540.