Three-Dimensional Visualization Simulation of Chinese Fir Stand Growth Based on Unity3D

In view of the problems existing in the 3D visualization simulation of stand growth, such as static discrete process, low visualization effect and limited expression of morphological parameters, this paper took the continuous survey data of 6 plots of Huangfengqiao State-owned forest farm in Hunan Province from 2012 to 2017 as data source. The stand age(A), Hegyi competition index(Hegyi-CI), and the tree's own diameter at breast height(DBH) were used as independent variables to establish the growth model of individual tree DBH. Then, according to the liner relationship models between DBH and free height(H), DBH and crown width(CW), and the relationship between H and height under living branch(UBH), the H, CW, and UBH were predicted. Finally, based on the dynamic dissection and organization of the Chinese Fir free three-dimesional(3D) model and Unity3D engine, continuous and dynamic visual simulation of stand growth was conducted. The results showed that the R-2 of DBH prediction model was as high as 0.995. The R-2 of the linear relationship models between DBH and H, DBH and CW, H and UBH was 0.831, 0.569 and 0.628. These provide good data support for the visual simulation of stand growth and ensure that the stand growth is in line with natural laws. The 3D visual simulation of stand growth based on the Unity3D engine is intuitive and fluent, and the frames per second(FPS) can be maintained at more than 50, which can basically meet the requirements of forestry scientific research and production practice.