**5. Conclusions**

In this study, we established a row model to accurately estimate the reflectance by considering the multiple scattering framework. We validated the row model using both computer simulations and in situ measurements. The validation results show that the row model can be used to simulate crop canopy reflectance at different growth stages, with an accuracy comparable to the computer simulations. The study modified the calculation accuracy of single scattering near the hotspot by considering the calculation of the two-overlapping relationship and hot kernel function. Moreover, the row model can be successfully used to simulate the multiple-scattering contribution by considering multiple-scattering equations based on the RT approach. Therefore, this can address the underestimation problem in row crops by ignoring multiple scattering calculations in the GO approach. Our results demonstrate that the multiple-scattering contribution is a very important process that needs to be considered in row modeling based on the GO approach. This study provided a potential mechanism for remote sensing inversion based on the physical model.

**Supplementary Materials:** The following are available online at http://www.mdpi.com/2072-4292/12/21/3600/s1 and (https://zenodo.org/record/4171572#.X54e\_1gzbIU) doi:10.5281/zenodo.4171572.

**Author Contributions:** Conceptualization, X.M. and Y.L.; methodology, X.M.; validation, X.M.; writing—original draft preparation, X.M.; writing—review and editing, X.M. and Y.L.; supervision, Y.L.; All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Acknowledgments:** The measured data in this paper were supported by the Watershed Allied Telemetry Experiment Research (WATER). Great thanks to Guohua Huang for providing the RGM model and related computer code. Finally, grea<sup>t</sup> thanks to help from Tiejun Wanng.

**Conflicts of Interest:** The authors declare no conflict of interest.
