3D Simulation On Tree Movement In Wind And Phototropic Growth Under Simplified Conditions

Tree is one of the important natural factors in VGE(Virtual GeographicalEnviroment). In recent years, the sense of reality tree modeling has become the focalpoint of the computer simulation technology applying on forestry, and is also thedevelopment trend of digital forestry. The randomicity and complexity of the treemorphostructure and physiological action bring much difficulty for sense of realitytree modeling. The existing modeling works still rest on the geometric shapemodeling, considering how to model tree that can interact with environmental factorsis also a frontierissues with great challenge.The tree moves and grows dynamically while interacting with environmentalfactors. The goals of this dissertation are modeling the dynamically tree thatcosiderting interacting with wind and light, and realizing3D tree expression under thedrive of simulation model.The article researches how to simulate the tree move inwind and phototropic grow in light under simplified conditions，then develops theprototype system and integrates the softerware function modes. The main researchwork and achievement of this paper are follows:1. The status quo of researches on virtual plant modeling and renderingtechnologies, especially the plant modeling considering interacting with environmentare summarized and commentated.The paper detailedly analysises the existing methodof simulating the tree swaying in wind and phototropic growth in light.; The paperintroduces the geometric modeling theory and method for a single tree, and the maintechnologies are parameterized stem modeling, the texture and leaf modeling based onimage, the rich expression of model based on LOD and randomization.2.Taking physics as theory principle, based on the analysis of the advantages anddisadvantages of existing method of the wind field modeling, the paper proposes asimplified wind simulation model, which bases on process function. Some reducedmaterial characteristics were applied to the virtual tree,.The socle beam was used tosimulate a segment of a stem as the mechanical analysis unit. The load anddeformation of the single tree in wind were computed based on the socle beam.Thenusing the force transmission and movement compounding method to solve the wholetree movement in wind. Base on these research work, the paper designs some coresofterware function modes such as wind field parameters mode, the controlling ofmaterial characteristics mode, the force compute mode.3.Based on the analysis of the phototropic mechanism of plant, the paper appliessimplified and mensurable process on the two qualitative relationship, which are therelationship between radiation amout and bend growth degree, and the relationshipbetween lighting intensity and net photosynthetic rate. A mathematic integrated modeswith far-ranging applicability in simulation of phototropic growth is proposed. The model provides flexible parameter interface, the computation flow and core algorithmof the bending gowth and expansion of organ based on biomass accumulation in light.4.Based on the realization of algorithm on the simulation of tree movement inwind and phototropic growth in light, developing the sofeware function modes.Thesemodes are integrated with the prototype system which developed by our researchgroup. Taking mao bamboo as a simulation object, the paper gives some simulationexamples. According to the different factors which affect the tree movement in windand phototropic growth in light, some contrastive simulation example groups wereproposed and analysised. The wind field condition, the morphostructure features andthe material characteristic were the different factors in the simulation of treemovement in wind. The lighting condition, photosynthesis features and the bendgrowth characteristic were the different factors which should be considered in thesimulation of tree phototropic growth in light.The simulation results are in accordancewith the empirical regularityl of tree movement and growth, so the simulation modesare confirmed to be effectual to a certain degree.