A GROWTH-MODEL HAVING THE ABILITIES OF GROWTH-REGULATIONS FOR SIMULATING VISUAL NATURE OF BOTANICAL TREES

Although the representation methods of botanical trees have been presented by several researchers in recent years, simulating natural tree features acquired in a growth process still remains a challenging problem. Since tree shape is significantly influenced by its growth environment, such as sunlight conditions and random ''accidental'' pruning of branches (e.g., caused by storm or a gardener), not only does no tree have a regular shape, but no two trees are identical, even if they are of the same species. In previous papers, we have shown an attractive fact that if we take into account the abilities of several growth regulations, such as heliotropism and dormancy break, we can easily simulate realistic irregular branching patterns. In this paper, we will present the improved growth model taking into account the following growth regulations: (a) withering, (b) heliotropism, (c) geotropism, and (d) apical dominance: (d-1) suppression to lateral shoots, (d-2) dormancy break, and (d-3) change in leadership. These growth regulations are implemented by employing an ''imaginary plant hormone'' for implementing the ability of the communication between all buds and branches of a tree. This means that any ''central control unit'' that keeps watch on the condition of the whole tree and issues commands for each bud and branch to control the growth is unnecessary for a tree. This point is one of the interesting features of our growth model.