FILLING GAPS BETWEEN MESHES OF TREE CROWN AND TREE TRUNK BASED ON BOUNDARY CONSTRAINTS AND COORDINATE PROJECTION FOR 3D TREE MODELLING - Wang, W. X.; Hong, L. P.; Huang, H. S.; Li, X. M.; Tang, S. J.; Guo, R. Z.; Xie, L. F. (Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci., 2023)