Abstract:

Virtual trees are models that describe the growth and development of a tree in 3D space by computer simulation.The study of virtual plants has been more and more popular in botany,agriculture,forestry,environmental sciences and computer.Growth modelling and visualization techniques are essential parts of virtual plants.Growth models of virtual trees include morphological structural models,functional models and functional-structural models.Functional-structural models may simulate the interaction between trees and its environment,whose outputs are 3D structure of trees.Therefore,functional-structural models are more close to realistic tree growth process and lead the trend of tree growth modelling.One of the major difficulties in tree visualization is the contradiction of between computer time and memory occupation and tree morphological structure complexity.Specific features different from normal objects for visualization cover self-similarity,ramification,branch bending,phototaxy,smoothly and un-smoothly blending branching etc.Tree visualization software is based on either pure graphics or functional-structural models,which has been applied in games,commerce,computer-assistant landscape design and forestry education,research and practice.Further work should be done in the collection and management of tree architecture data,the development of functional-structural models,the visualization techniques and forestry-oriented application.

Key words: virtual trees, growth modelling, visualization