Study On The Virtual Method And Key Technology In Simulation Of Maple Leaves Ageing

Leaves are essential parts to portray the natural beauty of plants, and play the pivotalrole in plants visualization and simulations. Plant leaves simulations are of criticalsignificance for digital agriculture, online education, film special effects and games design.However, leaves have complicated external morphology and internal construction, and theirshapes and textures change greatly with season and weather, all of which make the simulationand animation of leaves become quite difficult. As the previous research paid little attentionto the simulations of the morphology and color changes of leaves in different circumstancesand seasons, this dissertation took maple leaves as the main research object, and studied thethree-dimensional modeling method of plant leaves, dynamic simulation methods of curlyplant leaves and texture changes of plant leaves. Then we designed and developed thevisualization system for simulating the dynamic process of plant leaves ageing. The mainwork and conclusions are as follows:(1) We studied the method to generate three-dimensional leaf models based on leafimages, and proposed the method to build primary and secondary veins automaticallyaccording to the leaf silhouette, which can properly simulate veins distribution in the leafsilhouette and solve the problem that traditional approaches generating veins usually requiretoo much manual interactions. Meanwhile, how to render leaf models by double sided texturemapping techniques was discussed, by which the three-dimensional leaf models analogous toleaf photos were constructed.(2) The venation-skeleton based Rotation-Model is proposed in this paper. Maple andmagnolia leaves were used for studying, and various curly and folded leaves' models weresimulated by the Rotation-Model. Compared with previous approaches, Rotation-Model doesnot have complicated mechanical analysis or introduce excessive biological theory, whichmakes the running speed (about16~17fps) of our algorithm approach the real-timerequirement, and the animation of leaves deformation is fluid. Further, the simulation resultsof curly plant leaves are quite realistic by our method.(3) Based on the assumptions about leaves ageing, we built the mathematical model forthe chlorophyll, the carotenoid, the anthocyanin in leaves, the amounts of which change with leaves ageing process, as well as the mathematical relationships between these three pigmentsand the HSI color model. Additionally, the influences of primary veins, secondary veins, thepetiole and the light were taken into account for simulating leaves ageing, and from theprospective of one single leaf simulation, we modeled the color changes of maple leavesduring ageing in autumn, which showed the dynamic process from green to yellow and thento red. The simulation results are realistic to a certain degree, and the algorithm could showthe color changes of a maple leaf in autumn within1minutes.(4) We designed and explored the virtual system of plant leaves ageing on the basis ofPC platform. The three-dimensional leaf model could be generated based on the leaf imageby our system. Then, we could obtain all forms of leaf deformation through interactivelyinputting parameters controlling leaves deformation. After setting the frames of animation forcolor and morphology changes, we could simulate different kinds of leaves ageing effectsdynamically. The design of our system was combined with parameterized L-systems, bywhich the simple leaf clusters were built; therefore, the morphology and color changes forseveral leaves were simulated. The simulation results of our system indicate that the proposedmethods in this dissertation could realistically describe the shape and color changes of leavesin autumn.