Development and application of greenhouse light environment simulation technology based on light path tracing

•The variation of the PEP film transmittance with the angle is studied.•Greenhouse light environment simulation software was developed based on the principle of light path tracing.•Greenhouse light environment simulation software has a wide range of applications.•Optimization of the greenhouse structure based on the light environment. The interior light environment in greenhouses affects the growth of crops. Researchers have extensively studied improvements in greenhouse light environments. In this article, computer technology was used based on light path tracing and the Monte Carlo method, and a light environment simulation model that is applicable to various greenhouses was developed. Two types of greenhouses with complex roofs were simulated: three-span double-layer film greenhouses and multispan solar energy greenhouses. Experiments were performed to verify that the method could simulate the light environment distribution in greenhouses with various structures. The accuracy of the simulated average solar radiation intensity in greenhouses was greater than 85%, and the simulation correlation coefficient exceeded 0.90. Finally, by adjusting the ratio of rise to span of the greenhouse roof to optimize the greenhouse light environment, the greenhouse light distribution optimization results were found to be consistent between the two types of greenhouses, which verifies the effectiveness of the optimization. At three time points (9:00, 12:00, and 15:00), the horizontal section of the crop canopy (1.5 m) was simulated to construct a light distribution cloud map, and the point cloud data were statistically analyzed. The results show that the influence of the ratio of rise to span on the light distribution uniformity was more significant than that of the total radiation intensity. With an increasing the ratio of rise to span of the three-span double-film and multispan solar energy greenhouses, the total radiation intensity first increased and then decreased, and the light distribution uniformity showed a decreasing trend. When the ratio was 0.05, the total radiation intensity was high. Compared with that in the test greenhouse, the light intensity maximum increased by 6.95% and 6.64%, respectively, and the light distribution uniformity maximum increased by 14.49% and 14.74%, respectively. Combining the two factors of total radiation intensity and light distribution uniformity, the ratio of rise to span of these two types of greenhouses was maintained at 0.05.